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Sample records for weed alexandergrass brachiaria

  1. Competitivity of the common-bean plant relative to the weed alexandergrass [Brachiaria plantaginea (link hitch.] Competitividade do feijoeiro-comum com o capim-marmelada [Brachiaria plantaginea (link hitch.

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    Telma Passini

    2003-01-01

    Full Text Available Methodologies of competitive interaction quantification between weeds and crops are not widely elucidated and compared in the literature. The competitive ability of common-bean (Phaseolus vulgaris relative to alexandergrass (Brachiaria plantaginea was assessed and two approaches of replacement series experiment analysis were compared. The response of the species to the presence of each other at different densities and proportion was evaluated. Replacement series at total densities of 625, 816 and 1,111 plants m-2 were performed at the proportions of common-bean:alexandergrass of 100:0 (pure stand of common-bean, 75:25, 50:50, 25:75 and 0:100% (pure stand of alexandergrass, at four replicates in a randomized block design. Data analyses were performed by the qualitative compared to the quantitative approach. The quantitative approach provided larger number of information than did the qualitative approach, and indicated that there was intraspecific competition among common-bean plants, and a minimum of interspecific competition from alexandergrass. There was no intraspecific competition among alexandergrass plants, being the crop effect on the weed larger than the effect among alexandergrass plants. The ecological niche differentiation was partial, since the crop intraspecific competition was larger than the interspecific, and the last one was negligible, at the same time that the weed interspecific competition was larger than the intraspecific. Common-bean, as a competitor species, is superior to alexandergrass.As metodologias de quantificação das interações competitivas entre plantas cultivadas e daninhas não estão amplamente elucidadas e comparadas na literatura. A competitividade da cultura de feijão-comum (Phaseolus vulgaris em relação ao capim-marmelada (Brachiaria plantaginea foi avaliada pela comparação entre o método qualitativo e um método quantitativo de análise de resultados. A resposta de cada espécie à presença da

  2. Viabilidade de sementes de papuã (Brachiaria plantaginea e a cobertura do solo com palha Alexandergrass (Brachiaria plantaginea seed viability and soil cover with straw

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    Giovani Theisen

    1999-09-01

    Full Text Available O objetivo deste trabalho foi determinar o efeito de palha de aveia preta (Avena strigosa sobre o solo, na dormência e quiescência de sementes de papuã (Brachiaria plantaginea. Os tratamentos testados foram cobertura do solo (0; 2,6; 5,2; 7,8 e 10,5t/ha, o tempo de permanência das sementes submetidas à ação da cobertura do solo (40, 70, 100, 200 e 300 dias e o posicionamento das sementes (2 e 10cm. Elevados níveis de cobertura sobre o solo aumentaram o percentual de sementes de papuã viáveis. Sementes próximas da superfície do solo apresentaram menor dormência e quiescência do que aquelas posicionadas a 10cm de profundidade. A dormência e a quiescência das sementes de papuã se reduziram com o decorrer do tempo.The objective of this work was to determine the effect of black oat (Avena strigosa residues on the viability of alexandergrass (Brachiaria plantaginea seeds. The factors studied were the level of residues on the soil (0, 2.6, 5.2, 7.8 and 10.5t/ha, the time of permanence of seeds in soil submitted to action of residues (40, 70, 100, 200 and 300 days and the seed placement (2 and 10cm. High levels of crop residues on the soil surface increased the seed viability. Seeds placed at 2.0cm presented smaller dormancy and quiescence than those at 10cm depth. Seed dormancy and quiescence were reduced with time.

  3. Manejo da Planta Daninha Brachiaria plantaginea Resistente aos herbicidas Inibidores da ACCase Management of the Weed Brachiaria plantaginea Resistant to ACCase Inhibitor Herbicides

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    P.J. Christoffoleti

    2001-04-01

    study a population of alexandergrass (Brachiaria plantaginea resistant to ACCase inhibitor herbicides (ariloxyphenoxypropionic and cyclohexanodiones, usually sprayed on soybean under the conservation tillage system. Two experiments were conducted, one under field conditions, comparing the efficacy of non-selective herbicides to ACCase inhibitors, and another under greenhouse conditions, using ACCase inhibitors with nitrogenous additives in the spray solution. Resistant seeds were collected from a site of suspected resistant population, and compared to a population of alexandergrass that had never been sprayed with ACCase inhibitors, the susceptible population. The experiment with non-selective herbicides was conducted under field conditions, but plants were confined to pots of 50 L capacity, avoiding the dissemination of the seeds to adjacent areas. It was then concluded that resistant plants did not show multiple resistance to non selective herbicides with alternative mechanisms of action, with glyphosate, paraquat, paraquat + diuron, MSMA and glufosinate alternative herbicides being possible to be used to control the weed during the winter to manage populations of alexandergrass resistant to ACCase inhibitor herbicides. The additive experiment was conducted under greenhouse conditions in pots, using seeds from the same populations used in the non selective experiment. The herbicides tested were ACCase inhibitors, and the additive treatments were ammonium sulfate and urea. It was then concluded that the additives did not enhance ACCase inhibitor herbicide efficacy in neither of the alexandergrass populations.

  4. Banco de sementes de plantas daninhas em solo cultivado com pastagens de Brachiaria brizantha e Brachiaria humidicola de diferentes idades Weed seed bank in soil cultivated with pasture of Brachiaria brizantha and Brachiaria humidicola of different ages

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    D.S.M. Silva

    2001-08-01

    Full Text Available Estudou-se o banco de sementes do solo de uma pastagem de Brachiaria brizantha com 4 anos de idade e de pastagens de Brachiaria humidicola com 4, 15 e 20 anos de idade, localizadas no nordeste do Estado do Pará. Objetivou-se avaliar a influência da espécie forrageira e da idade da pastagem no tamanho e na composição do banco de sementes de plantas daninhas do solo. Cada pastagem foi dividida em cinco áreas de aproximadamente 500 m², sendo retiradas, de cada área, 10 subamostras de solo na profundidade de 0-10 cm. Cada amostra composta das 10 subamostras de solo foi homogeneizada, identificada, distribuída em bandeja de plástico e levada para germinar em casa de vegetação durante um período de 15 meses. O banco de sementes do solo da pastagem de B. brizantha foi em torno de 10 vezes menor que o da pastagem de B. humidicola de mesma idade. Com relação ao efeito da idade da pastagem, entre as pastagens de B. humidicola, o banco de sementes foi menor naquela de 20 anos de idade (1.247 sementes m-2, não tendo sido detectada diferença significativa entre as pastagens de 15 (11.602 sementes m-2 e 4 (9.486 sementes m-2 anos de idade. As famílias botânicas Cyperaceae, Rubiaceae e Labiateae foram as de maior predominância entre as plantas daninhas infestantes da área, em todos os tratamentos estudados.The objective of this work was to study the soil seed bank of a four-year-old Brachiaria brizantha pasture soil, and in pasture soils of four, 15 and 20 year-old Brachiaria humidicola, in northeastern Pará, Brazil, to evaluate the influence of the forage species and pasture age on weed seed bank size and composition. Each pasture area was divided into five plots of about 500 m², from which 10 soil sub-samples were collected at a depth of 0-10 cm. The soil from each plot was mixed, identified, placed in plastic trays, and put to germinate in a greenhouse during a 15-month period. The seed bank of the four-year-old B. brizantha pasture

  5. Nível de dano econômico de Brachiaria plantaginea na cultura de milho irrigado Economic weed threshold (EWT of Brachiaria plantaginea in irrigated corn crop

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    R.A. Vidal

    2004-03-01

    reas onde foram aspergidos herbicidas residuais. Conclui-se, também, que o NDE de BRAPL em milho aumenta à medida que o preço da cultura diminui e o custo do controle aumenta e que o aumento do preço de grãos reduz o impacto do custo do controle de BRAPL no retorno econômico da cultura.Economic weed threshold (EWT consists of the number of weeds impacting crop grain yield to justify the cost of their control. The objectives of this work were to evaluate the feasibility of using herbicide experiment results to establish EWT, based on regression between corn grain yield and Brachiaria plantaginea (BRAPL density assessed on several occasions; and to evaluate crop price and weed control cost impact on EWT. BRAPL densities were determined by applying herbicide treatments allowing several levels of weed emergence and, consequently several levels of weed-crop interference. Weed density was evaluated at 10, 20, 30, 40 and 50 days after crop emergence (DAE to cover the critical weed-crop competition period. Crop grain yield was determined at crop maturity. The results of the regression between BRAPL density and corn grain yield have adjusted exponential decay curves for assessments performed at 10 and 20 DAE and sigmoidal curves at 30, 40 and 50 DAE. EWT of BRAPL in corn, based on densities assessed at 20 DAE and for 10 t ha-1 of grain yield, ranged from 0.2 and 2.0 plants m-2, depending on crop price and weed control cost. EWT assessed at 50 DAE ranged between 1.5 and 13 plants m-2. This work confirmed that weed densities increase with time, allowing to conclude that EWT can be determined from density data assessed on experiments designed to test residual herbicides. Therefore, the EWT obtained are appropriate for situations requiring post-emergence herbicides in areas treated with residual herbicides. The EWT of BRAPL in corn crop increases with the increase of crop prices and reduction of weed control costs; and grain price increase reduces the relative impact of weed

  6. Redução da infestação de Brachiaria plantaginea em soja pela cobertura do solo com palha de aveia-preta Reduction of Brachiaria plantaginea infestation on soybean crop with black oat residues

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    GIOVANI THEISEN

    2000-04-01

    Full Text Available Este trabalho foi conduzido em área da Universidade Federal do Rio Grande do Sul, em Eldorado do Sul, RS, em 1996/97, com o objetivo de avaliar os efeitos de resíduos de aveia-preta (Avena strigosa Schreb. sobre o solo na densidade de papuã (Brachiaria plantaginea (Link Hitch. e no rendimento da cultura da soja (Glycine max L. Merrill. O experimento foi conduzido em delineamento de blocos casualizados em parcelas subdivididas, com quatro repetições; os tratamentos método de controle de papuã (nas parcelas e cobertura do solo (nas subparcelas foram arranjados em esquema fatorial. A densidade da planta daninha diminuiu de forma exponencial com o aumento da cobertura de aveia sobre o solo, variando de 829 a 86 plantas/m² para níveis de cobertura 0,0 t/ha e 10,5 t/ha, respectivamente. Houve maior infestação de papuã nas linhas do que nas entrelinhas da cultura. Não houve efeito da cobertura vegetal no rendimento da soja quando a cultura foi mantida livre de papuã. Por sua vez, níveis crescentes de resíduos vegetais sobre o solo controlaram papuã e aumentaram linearmente o rendimento da cultura. Nas condições de alta infestação da área, a produção de grãos aumentou na razão de 158 kg/ha de grãos por tonelada de palha sobre o solo.This work was conducted at Universidade Federal do Rio Grande do Sul, in Eldorado do Sul, Rio Grande do Sul State, Brazil, during 1996/97, to evaluate the effect of black oats (Avena strigosa Schreb. residues on alexandergrass (Brachiaria plantaginea (Link Hitch. density and on soybean (Glycine max L. Merrill yield. Treatments were arranged in split-plot in a randomized complete block design with four replicates, with weed control method as main plots and level of black oat residues as subplots. An exponential reduction of alexandergrass density was observed, with data varying from 829 to 86 plants/m² for levels of straw on the soil surface of 0 to 10.5 ton/ha, respectively. Higher weed

  7. Nitrogen fertilizer use efficiency, recovery and leaching of an alexandergrass pasture

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    Laércio Ricardo Sartor

    2011-06-01

    Full Text Available Nitrogen usually determines the productive potential of forage crops, although it is highly unstable in the environment. Studies on recovery rates and use efficiency are important for more reliable fertilizer recommendations to reduce costs and avoid environmental pollution. The purpose of this study was to evaluate N use efficiency and recovery rate of Alexandergrass pasture (Brachiaria - Syn. Urochloa plantaginea as well as N-NO3- and N-NH4+ soil concentrations using different levels of N fertilization under two grazing intensities. The experiment was arranged in a randomized block design in a factorial scheme with three replications. Treatments consisted of three N rates (0, 200 and 400 kg ha-1 N and two grazing intensities termed low mass (LM; forage mass of 2,000 kg ha-1 of DM and high mass (HM; forage mass of 3,600 kg ha-1 of DM under continuous stocking and variable stocking rates. Results of N fertilization with 200 kg ha-1 were better than with 400 kg ha-1 N. There was a significant effect of N rates on soil N-NO3-concentration with higher levels in the first layer of the soil profile in the treatment with 400 kg ha-1 N. Grazing intensity also affected soil N-NO3- concentration, by increasing the levels under the higher stocking rate (lower forage mass.

  8. Dose reduzida de clethodim no controle de papua na cultura da soja, em função da época de aplicação Reduced rate of clethodim for alexandergrass: control in soybeans as a function of application time

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    Nilson G. Fleck

    1997-01-01

    Full Text Available Foi realizado um experimento a campo em Eldorado do Sul, RS, no ano agrícola de 19 94 /9 5, para avaliar o controle de papuã (Brachiaria plantaginea (Linck Hitchc., que ocorreu numa população média de 95 plantas/m2. Foi avaliado o herbicida clethodim à dose-plena (120g/ ha e à meia-dose (60g/ha. A cultivar de soja utilizada foi RS-7 Jacuí e usado o delineamento experimental em blocos casualizados com quatro repetições. Os tratamentos foram aplicados aos 14, 21, 28 e 35 dias após a emergência da soja (DAE. Foram mantidas testemunhas capinadas, com operações iniciadas nas mesmas épocas de aplicação do herbicida, e uma testemunha infestada durante todo o ciclo da cultura. O controle foi avaliado visualmente, em três ocasiões, através de escala percentual. Os graus de controle de papua obtidos à dose-plena foram equivalentes entre si quando aplicado nas três primeiras épocas, com eficiência entre 95 e 98% na última avaliação. A meia-dose mostrou, para as três primeiras épocas de aplicação, resultados semelhantes aos de doseplena, porém em níveis um pouco inferiores, situando-se entre 85 e 95% o controle obtido na última avaliação. O controle do papuã foi mediano quando clethodim foi aplicado aos 35 DAE, tanto par a dose-plena quanto para meiadose. Quanto ao rendimento de grãos, não houve diferença estatística significativa entre os tratamentos em suas várias modalidades, embora todos tenham superado a testemunha infestada, com incrementos na produtividade de grãos entre 73 e 10 5% . O experimento permite concluir pela viabilidade da utilização de meiadose de clethodim para o controle de papua em soja, realizando as aplicações preferencialmente até a quarta semana após a emergência da cultura.A field trial was carried out in Eldorado do Sul, RS, during the 1994/95 growing season to evaluate Alexandergrass (Brachiaria plantaginea (Linck Hitchc control, that occurred with na average population of 95

  9. Atividade microbiana e produção de milho (Zea mays e de Brachiaria brizantha sob diferentes métodos de controle de plantas daninhas Microbial activity and production of corn (Zea mays and Brachiaria brizantha under different methods of weed control

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    A. Jakelaitis

    2007-03-01

    biomass production of corn and Brachiaria brizantha intercroping. The treatments were constituted of corn and B. brizantha intercropping, treated with atrazine (1,500 g ha-1, or with atrazine + nicosulfuron (0, 4 and 32 g ha-1 and two controls represented by intercropping control with and without weeds. Herbicides were applied 30 days after corn emergence (DAE. The experiment was arranged in a randomized block design, with four replicates. Microbial biomass (MB, respiration and metabolic quotient (qCO2 obtained from soil samples seven days after herbicide application on corn flowerage and pre-harvesting were evaluated. No-treated soil samples were collected in field and treated with atrazine (1,500 g ha-1 + nicosulfuron (0, 2, 4, 8, 16 and 32 g ha-1 under laboratory condition. Weed and B. brizantha dry matter and corn grain yield were evaluated at corn pre- harvesting. Methods of control did not influence respiration, MB nor qCO2 but higher MB in flowerage and higher qCO2 were observed after seven days of application. Higher weed dry matter production was observed in the control treated only with atrazine. Forage yield of B. brizantha was superior in the control plots without weeds, while corn grain yield was superior both in the control plots without weeds and treated with nicosulfuron.

  10. Controle de plantas daninhas em soja com doses reduzidas de herbicidas Soybean weed control with reduced rates of herbicides

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    Nilson G. Fleck

    1995-01-01

    Full Text Available doses reduzidas dos herbicidas haloxyfop-methyl e sethoxydim para controlar papuã [Brachiaria plantaginea (Link Hitchc.] na cultura da soja [Glycine max (L. Merrill. Haloxyfop-methyl foi testado nas doses de 120, 90, 60 e 30+30 g/ha; já sethoxydim o foi nas doses de 220, 165, 110 e 55+55 g/ha. A pulverização dos herbicidas ocorreu 15 dias após a semeadura da soja; nesta ocasião, a maioria das plantas de papuã encontravam-se no estádio de três a quatro folhas. Os tratamentos herbicidas com doses reduzidas em aplicações seqüenciais, tiveram a segunda pulverização realizada 11 dias após a primeira aplicação. Foi obtido controle ao redor de 95% para todos os tratamentos, com pequenas variações não significativas. O rendimento de grãos de soja foi equivalente entre a testemunha capinada e os tratamentos haloxyfop-methyl a 90 e 60 g/ha, sethoxydim a 220, 110 e 55+55 g/ha. Os demais tratamentos foram semelhantes entre si, superando a testemunha infestada, a qual apresentou o menor rendimento de grãos. Os resultados evidenciam a viabilidade da utilização de doses reduzidas, as quais podem alcançar patamares de produtividade tão elevados quanto aqueles obtidos com doses plenas.During the 1993/94 growing season, it was carried out a field experiment at the Agronomic Experimental Station of Federal University of Rio Grande do Sul, in Eldorado do Sul, RS, Brazil, in order to evaluate the possibility of using reduced rates of the herbicides haloxyfop-methyl and sethoxydim for Alexandergrass [Brachiaria plafitaginea (Link Hitchc.] control in soybeans. Haloxyfop-methyl was tested at 120, 90, 60, and 30+30 g/ha, where as sethoxydim was at rates, of 220, 165, 110, and 55+55 g/ha. Herbicide spraying occurred 15 days after soybean sowing; at this time Alexandergrass plants ranged from one leaf to one tiller. Herbicide treatments using reduced rates in sequential applications had the second spraying accomplished 11 days after the first one

  11. Effects of plant density and proportion on the interaction between wheat with alexandergrass plants

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    Leonardo Bianco de Carvalho

    2011-01-01

    Full Text Available Determination of competitive relationships among plant species requires appropriate experimental designs and method of analysis. The hypothesis of this research was that two species growing in coexistence show different growth and development due to their relative competitiveness. This research aims to measure the relative competitiveness of wheat crop compared to Alexandergrass by the interpretation of plant density and proportional effects using replacement series experiments. Monocultures were cultivated in densities of 1, 3, 5, 10 and 15 plants per pot and analyzed by regression of dry mass data. Mixture experiment was cultivated in wheat:Alexandergrass proportions of 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 and 6:0 plants per pot and analyzed by graphical interpretation of growth and production characteristics. Both experiments were carried out in randomized complete block design with four replicates. Alexandergrass was more sensitive to intraspecific competition than wheat. Alexandergrass was lightly more competitive than wheat. Number and weight of spikes and number of tillers were the wheat characteristics more affected by Alexandergrass interference.

  12. Efeito da prevenção de produção de sementes pelas plantas daninhas e da aplicação de herbicida em jato dirigido na densidade de infestação na cultura do milho em anos sucessivos Effect of weed seed production prevention and 10-year herbicide direct spray on weed density in corn during sucessive years

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    F. Skóra Neto

    2001-04-01

    Full Text Available Um experimento com dez anos de duração foi realizado em Ponta Grossa-PR para avaliar o efeito da prevenção de produção de sementes pelas plantas daninhas e da aplicação de herbicida em jato dirigido na densidade de infestação em plantios direto e convencional. As plantas daninhas predominantes na área foram capim-marmelada (Brachiaria plantaginea, capim-colchão (Digitaria ciliaris, amendoim-bravo (Euphorbia heterophylla, poaia-branca (Richardia brasiliensis e guanxuma (Sida rhombifolia. O controle da frutificação das plantas daninhas durante dez anos reduziu a densidade das espécies presentes em mais de 99%. A redução foi variável entre as espécies, mas em todas elas foi mais intensa nos primeiros anos. A densidade populacional em anos subseqüentes, quando se permitia a reinfestação da área após o controle inicial das plantas daninhas (testemunha, variou conforme as condições climáticas e culturais. A aplicação de herbicida em jato-dirigido foi uma prática eficiente no controle da frutificação das plantas daninhas suscetíveis aos herbicidas, mas selecionou o capim-colchão quando o controle desta espécie foi insatisfatório. A equação que descreve o comportamento dos tratamentos sem ressemeadura e com jato dirigido foi do tipo exponencial negativa. Os resultados obtidos por meio da densidade de plantas emergidas são confirmados pela avaliação do banco de sementes em cada tratamento.A ten-year corn field experiment was conducted at Ponta Grossa (Parana, Brazil to evaluate the effect of weed seed production prevention and herbicide direct spray on weed density in successive years, under two different tillage treatments (conventional and no-till. The main weeds in the area were Alexandergrass (Brachiaria plantaginea, crabgrass (Digitaria ciliaris, wild poinsettia (Euphorbia heterophylla, pusley (Richardia brasiliensis and arrowleaf sida (Sida rhombifolia. The prevention of weed seed production during ten years

  13. Ingestive behavior of heifers in Alexandergrass pasture receiving different amounts of oat grain as supplement

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    Maria José de Oliveira Sichonany

    2015-08-01

    Full Text Available This study was conducted to evaluate the ingestive behavior, displacement patterns and meal dynamics of beef heifers in Alexandergrass pasture (Urochloa plantaginea (Link. Hitch receiving different amounts of oat grain: 0, 0.80 and 1.12% of body weight (BW. The grazing method was continuous with put-and-take stocking. The experimental design was completely randomized following a repeated measure arrangement. The grazing time decreased and the idling time increased when beef heifers were supplemented, independently of supplement amount, while the rumination time was similar across supplement amounts. The number of feeding stations per minute and the number of steps taken between each feeding station were similar regardless of supplementation. When receiving 1.12% of BW of oat grain, heifers remained longer in each feeding station and took fewer steps per minute. The number of meals decreased and the duration of breaks between meals increased when heifers received oat grain. The duration of each meal was similar for heifers receiving supplement than for those that did not. Understanding how animals adjust their grazing behavior and cope with changing environmental dynamics is essential for the development of management strategies designed to optimize animal production.

  14. Comportamento ingestivo de bezerros em pastos de Brachiaria brizantha e Brachiaria decumbens Ingestive behavior of calves on pastures of Brachiaria brizantha and Brachiaria decumbens

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    Anderson de Moura Zanine

    2006-10-01

    Full Text Available Foi conduzido um experimento com o objetivo de avaliar o comportamento de bezerros em pastagens de Brachiaria brizantha e Brachiaria decumbens, no sistema de lotação contínua com taxa de lotação variável. O delineamento experimental foi o inteiramente casualizado, com dois pastos representando os tratamentos, cada um com cinco repetições. O período experimental foi de 30 dias, sendo 20 para adaptação dos animais e 10 para avaliações, que consistiram de três, com duração de 24h cada, em intervalos de cinco dias. Os bezerros pastejaram menos tempo no pasto de Brachiaria brizantha, com tempo de 9,75h, enquanto que o pastejo na Brachiaria decumbens foi de 11,3h. Comportamento diferente foi observado para o tempo de ruminação: 6,8 e 6,4 para os pastos de Brachiaria brizantha e Brachiaria decumbens, respectivamente. O número de bocados por minuto foi menor para a Brachiaria decumbens, 31,15, enquanto que, para a Brachiaria brizantha, os bezerros pastejaram com uma taxa de bocados de 34,91 bocados por minuto. Os bezerros tiveram um ganho de peso médio diário superior no pasto de Brachiaria brizantha (390g dia-1, enquanto que, para a Brachiaria decumbens, o ganho diário foi de 340g dia-1.An experiment was carried out to evaluate the ingestive behavior of calves on Brachiaria brizantha and Brachiaria decumbens pastures, under continuous stocking with variable stocking rate. The experimental design was entirely randomized, with two treatments (two pastures, and five replicates per treatment. The experimental period lasted 30 days, consisting of days 20 for adaptation of animals and 10 for behavioral evaluations that consisted of three periods of 24:00h each, in intervals of five days. The calves spent less time grazing Brachiaria brizantha pasture (9,8h than they did on the Brachiaria decumbens (11,3h. Different rumination times had been observed, 6,8 and 6,4 h for the animals grazing Brachiaria brizantha and Brachiaria decumbens

  15. Weed supression by smother crops and selective herbicides

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    Severino Francisco José

    2004-01-01

    Full Text Available Using a smother crop is thought to suppress weed density and to add other beneficial effects in sustainable agricultural systems. Weed suppression ought to be considered an essential component of integrated weed management. However, very little is known about the effects of green manure plants on weeds. This study evaluated the influence of three green manure species on weed suppression and selectivity of herbicides. A field experiment was designed to determine the effect of the green manure species Crotalaria juncea, Arachis pintoi and pigeon pea on the weeds Brachiaria decumbens, guineagrass and hairy beggarticks, and on the natural weed infestation in the inter rows area of an avocado orchard. The weed species were suppressed differently by each green manure species. Soil samples collected from the field experiment presented a residual effect, of at least 30 d, in suppressing weed seed bank recruitment; this residual effect was caused by the residues of the green manure present in the soil. When the green manure was incorporated into the top 5 cm of soil or left on the surface, in a greenhouse experiment, the emergence of weed seeds was significantly inhibited, depending on the species, and on the amount and depth of green manure incorporation. Greenhouse experiments indicate that pre-emergence herbicides cause lower phytotoxicity than post-emergence Arachis pintoi. Smother crops using green manure species, when well established in an area, provide additional weed control to the cropping system and are effective and valuable tools in integrated weed management.

  16. Brachiaria spp. poisoning of ruminants in Brazil

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    B. Riet-Correa; M.B. Castro; R.A. Lemos; G. Riet-Correa; V. Mustafa; F. Riet-Correa

    2011-01-01

    Brachiaria species are the most important grasses for cattle production in Brazil. However, a limiting factor for the use of Brachiaria spp. is their toxicity. Most outbreaks of hepatogenous photosensitization are caused by B. decumbens; however B. brizantha, B. humidicola and B. ruziziensis can also cause poisoning. The poisoning affects cattle, sheep, goats and buffalo. Sheep are more susceptible than other animal species and the young are more susceptible than adults. There are differences...

  17. Hábito de pastejo de vacas lactantes Holandês x Zebu em pastagens de Brachiaria brizantha e Brachiaria decumbens Grazing behavior of Holstein x Zebu lactating cows in pastures of Brachiaria brizantha and Brachiaria decumbens

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    A.M. Zanine

    2007-02-01

    Full Text Available Avaliou-se o comportamento ingestivo de pastejo de vacas leiteiras em pastagens de Brachiaria brizantha e Brachiaria decumbens, em sistema de lotação contínua com taxa de lotação variável. O delineamento experimental foi o inteiramente ao acaso, com os dois pastos representando os tratamentos, cada um com cinco repetições. O período experimental foi de 30 dias, sendo 20 para adaptação dos animais e 10 para avaliações, em número de três, com duração de 24h cada, em intervalos de cinco dias. O tempo de pastejo da Brachiaria brizantha foi menor, 10,82h, que o tempo de pastejo da Brachiaria decumbens, 12,86h. Comportamento oposto foi observado para o tempo de ruminação, 7,95 e 6,45h para os pastos de Brachiaria brizantha e Brachiaria decumbens, respectivamente. A quantidade de bocados por minuto foi menor na Brachiaria decumbens, 37,30, e maior na Brachiaria brizantha, 42,12. Houve adequação entre os tempos de pastejo, ruminação e taxa de bocados, de modo que o total de bocados e o tempo de ócio não foram diferentes entre os dois pastos.The grazing behavior of lactating cows in pastures of Brachiaria brizantha and Brachiaria decumbens, in system of continuous stocking with variable stocking rate was evaluated. A completely randomized experimental design, with two treatments (pastures and five replicates was used. The experimental period last 30 days, 20 for adaptation of the animals and 10 for three experimental evaluations, of 24h each, in intervals of five days. The grazing time of cows on the Brachiaria brizantha pasture, 10,82h, was lower than on the Brachiaria decumbens, 12,86h. Inverse behavior was observed for rumination time, 7,95 and 6,45h for cows on the pastures of Brachiaria brizantha and Brachiaria decumbens, respectively. The amount of bite per minute was lower for cows on the Brachiaria decumbens, number 37,30h, than on the Brachiaria brizantha, 42,12h. There was an adequacy among grazing time, rumination time

  18. Robotic weeding and automated weed measurements

    DEFF Research Database (Denmark)

    Christensen, S.; Søgaard, H.T.; Jørgensen, R.N.

    2003-01-01

    The goal of decreasing herbicide usage has so far focused on reducing the herbicide dosage or replacing chemical weed control by hoeing and harrowing. The conventional weed control strategy is to apply the same dose of herbicide or the same intensity of hoeing and harrowing in the whole field. Th...... the state-of-the-art of automated weed measurement methods and the research projects concerning autonomous platform and information system for crop and weed monitoring and robotic weeding....

  19. Brachiaria spp. poisoning of ruminants in Brazil

    Directory of Open Access Journals (Sweden)

    B. Riet-Correa

    2011-03-01

    Full Text Available Brachiaria species are the most important grasses for cattle production in Brazil. However, a limiting factor for the use of Brachiaria spp. is their toxicity. Most outbreaks of hepatogenous photosensitization are caused by B. decumbens; however B. brizantha, B. humidicola and B. ruziziensis can also cause poisoning. The poisoning affects cattle, sheep, goats and buffalo. Sheep are more susceptible than other animal species and the young are more susceptible than adults. There are differences in susceptibility among animals of the same species and it has been suggested that this resistance is genetic. Also has been suggested that buffalo and probably some sheep are resilient, i.e. when poisoned these animals have histologic lesions and high GGT serum concentrations, but do not show clinical signs. In general, saponin concentrations are higher in growing plants, but outbreaks occur all over the year, probably due to unexplained rise in saponin concentration in the plant. A clinical syndrome of progressive weight loss and death, without photosensitization, has been reported in cattle poisoned by B. decumbens. Main preventive measures are based on the selection of resistant or resilient animals and on the development of Brachiaria species or varieties with low saponin concentration.

  20. The seasonal variations of allelopathic activity and allelopathic substances in Brachiaria brizantha.

    Science.gov (United States)

    Kobayashi, Ai; Kato-Noguchi, Hisashi

    2015-12-01

    Controlling weeds through allelopathy is one strategy to reduce dependency on synthetic herbicides. The plant shoots of the grass Brachiaria brizantha incorporated into the field soil were found to inhibit the growth of several plant species. We investigated the variations of allelopathic activity and allelopathic substances in B. brizantha harvested in June, October and January. All extracts of B. brizantha obtained from June, October and January inhibited the root and shoot growth of cress, lettuce, Phleum pretense and Lolium multiflorum in a concentration dependent manner. However, the inhibitory activity of B. brizantha of June and October was greater than that of B. brizantha of January. Concentrations of three potent allelopathic active substances, (6R,9S)-3-oxo-α-ionol, (6R,9R)-3-oxo-α-ionol and 4-ketopinoresinol were also greater in B. brizantha of June and October than those in B. brizantha of January. The results suggest that the allelopathic activity and the levels of those allelopathic active substances are greater in B. brizantha of June and October than those in B. brizantha of January. It is possible that B. brizantha could be useful for a weed suppressive residue or soil additive materials in the variety of agricultural settings to develop sustainable agriculture options. The effectiveness of B. brizantha of June and October as a weed suppressive agent may be greater than that of January.

  1. Efficiency of a reduced herbicide rate for Brachiaria brizantha control in sugarcane Eficiência de subdoses de herbicidas no controle de Brachiaria brizantha em cana-de-açúcar

    Directory of Open Access Journals (Sweden)

    S.P. Tironi

    2012-12-01

    Full Text Available At different growth stages, weeds present different sensitivities to herbicides. Thus, the registered herbicide rate may be reduced under specific conditions, while maintaining satisfactory weed control. This study evaluated the efficiency of reduced rates of the formulated herbicide mixture Velpar K WG® (hexazinone + diuron + Volcane® (MSMA for Brachiaria brizantha control at different growth stages. Optimum weed control efficiency was obtained when applying 50% of the recommended rate in younger plants (plants with one to four leaves. In late applications, it is necessary to increase the herbicide rates and, under these conditions, 90% of the recommended rate for (diuron + hexazinone + MSMA was estimated to be the most economical one.Em estádios diferentes de crescimento, as plantas daninhas apresentam sensibilidade diferenciada aos herbicidas. Desse modo, as doses registradas dos herbicidas podem ser reduzidas em condições específicas, mantendo-se o controle satisfatório das plantas daninhas. Neste trabalho, avaliou-se a eficiência de subdoses da mistura dos herbicidas formulados Velpar K WG® (hexazinone + diuron + Volcane® (MSMA no controle de Brachiaria brizantha em diferentes estádios de crescimento. Ótima eficiência de controle da espécie daninha foi obtida com aplicação de 50% da dose recomendada, quando os herbicidas foram aplicados em plantas mais jovens (plantas com uma a quatro folhas. Em aplicações tardias, comprovou-se a necessidade de aumentar a dose para obter controle eficiente; nessas condições, a dose econômica ótima estimada foi de 90% da dose recomendada da mistura dos herbicidas (diuron + hexazinone + MSMA.

  2. Upland rice yield as affected by Brachiaria coverage management

    Directory of Open Access Journals (Sweden)

    Adriano S. Nascente

    2015-01-01

    Full Text Available An important point in no-tillage system is the time between cover crop glyphosate desiccation and rice sowing. This study aimed to verify the effect of Brachiaria ruziziensis management time before rice sowing on rice yield and its components. The experiment was conducted under greenhouse conditions and consisted of four types of B. ruziziensis management: with Brachiaria and with herbicide (WBWH, without Brachiaria shoots and with herbicide (NBWH, without Brachiaria shoots and without herbicide (NBNH, and with Brachiaria and without herbicide (WBNH, at four times: 30, 20, 10, and 0 days, preceding the rice sowing. The amount of B. ruziziensis dry matter increased as the management was done closer to the rice sowing date. The WBWH and WBNH managements (this one causes the lowest rice grain yield must be done 30 days before rice sowing; while NBWH management must be done ten or more days before rice sowing. On the other hand, NBNH management (this one favors the best rice grain yield can be done until rice sowing day. Despite some reduction in rice yield caused by the B. ruziziensis management, when it was done at the proper time the rice grain yield was similar to the control (without Brachiaria sowing and without herbicide application.

  3. Assessment of Caesium -137 accumulation from soil to autochthonous weeds

    International Nuclear Information System (INIS)

    Sreenivasa Chari, M.; Karuna Sagar, G.; Manjaiah, K.M.

    2017-01-01

    A study was conducted at Nuclear Research Laboratory (NRL), IARI, New Delhi to obtain radio cesium ( 137 Cs) Soil-to-plant transfer factors of autochthonous weeds at low level of contamination, where contamination is a legacy of experimental activities. Studied area is sporadically covered with autochthonous weeds mainly with Amaranthus viridis, Cynodon dactylon, Cassia auriculata, Brachiaria mutica, Parthenium hysterophorus, Bohervia diffusa and some taxonomically unidentified weeds. Extractability as well as bioavailability of 137 Cs was quantified by sequential extraction. In the representative plant and soil samples, 137 Cs activity was measured directly with the 2.5” × 2.5” NaI (TI) well type detector installed in 15 cm thick lead shield and single channel gamma analyzer. Transfer factors of grassy weeds were 0.143 to 0.310 (1.43 × 10 -2 to 3.1 × 10 -2 ), for broad leaved weeds 0.103 to 0.133 (1.03 × 10 -2 to 1.33 × 10 -2 ). Increase in the activity levels increased the transfer factors of weeds. Irrespective of activity levels higher transfer factors were observed in roots ranging from 0.13 to 0.28 (1. 3 × 10 -1 to 2.8 × 10 -1 ). At both the levels (40 and 80 µci) Cynodon dactylon recorded higher root and shoot transfer factor of 2.99 and 0.29 respectively, when compared to other weeds. Significantly lower transfer factors were observed in Parthenium hysterophorus. Geochemical partitioning shown that the reducible phase (56%) is the largest sink for 137 Cs in the studied soils

  4. Emergência e desenvolvimento de guanxuma (Sida rhombifolia, capim-braquiária (Brachiaria decumbens e cana-de-açúcar (Saccharum spp. influenciados por subprodutos da destilação do álcool Emergence and growth of arrowleaf sida (Sida rhombifolia, brachiaria grass (Brachiaria decumbens and sugarcane (Saccharum spp. as influenced by alcohol by-products

    Directory of Open Access Journals (Sweden)

    A.A.P.M. Azania

    2004-09-01

    Full Text Available Este trabalho objetivou avaliar os efeitos da aplicação de óleo de fúsel, comparativamente a vinhaça e flegmaça, sobre o desenvolvimento e a composição química de plantas de guanxuma (Sida rhombifolia, capim-braquiária (Brachiaria decumbens e cana-de-açúcar (variedade RB72454, cultivadas simultaneamente em casa de vegetação. As concentrações de 12,5; 25,0; 50,0; e 100,0% (v/v de cada subproduto e a testemunha (água foram aplicadas (numa taxa equivalente a 150 m³ ha-1 no solo dos vasos (22 L, contendo uma planta de cana-de-açúcar (13 cm de altura e 100 sementes de cada planta daninha. O delineamento foi o inteiramente casualizado, com 13 tratamentos e 4 repetições, em esquema fatorial 3 x 4 (três tipos de resíduos e quatro concentrações, e uma testemunha adicional com água. O óleo de fúsel inibiu a emergência de Sida rhombifolia e Brachiaria decumbens e matou a cana-de-açúcar. A vinhaça e a flegmaça prejudicaram a emergência e o desenvolvimento de B. decumbens, bem como o de S. rhombifolia, mas não o da cana-de-açúcar.This research aimed to compare the effects of fusel oil application to those of vinasse and flegmass application on the growth and chemical composition of arrowleaf sida plants (Sida rhombifolia, brachiaria grass (Brachiaria decumbens and sugarcane (Saccharum spp., cultivated simultaneously under greenhouse conditions. Concentrations of 12.5,25.0,50.0 and 100.0 % (v/v of each by-product and the check treatment (water were applied (rate equivalent to 150 m³ ha-1 to soil on 22 L-pots, containing one sugar-cane plant (13 cm of height, and 100 seeds of each weed. The experimental design was completely randomized , with 13 treatments and 4 repetitions, in a 3x4 factorial scheme (3 by-products and 4 concentrations and an additional check treatment with water. The fusel oil inhibited Sida rhombifolia and Brachiaria decumbens emergence with no emergence being verified for sugarcane. The vinasse and

  5. Ecologically sustainable weed management

    NARCIS (Netherlands)

    Liebman, Matt; Baraibar, Bàrbara; Buckley, Yvonne; Childs, Dylan; Christensen, Svend; Cousens, Roger; Eizenberg, Hanan; Heijting, Sanne; Loddo, Donato; Merotto, Aldo; Renton, Michael; Riemens, Marleen

    2016-01-01

    Weed management is a critically important activity on both agricultural and non-agricultural lands, but it is faced with a daunting set of challenges: environmental damage caused by control practices, weed resistance to herbicides, accelerated rates of weed dispersal through global trade, and

  6. Horny Goat Weed

    Science.gov (United States)

    Horny goat weed is an herb. The leaves are used to make medicine. As many as 15 horny goat weed species are known as “yin yang huo” in Chinese medicine. Horny goat weed is used for weak back and knees, ...

  7. Nitrogen loss in Brachiaria decumbens after application of glyphosate or glufosinate-ammonium

    OpenAIRE

    Damin,Virginia; Franco,Henrique Coutinho Junqueira; Moraes,Milton Ferreira; Franco,Ademir; Trivelin,Paulo Cesar Ocheuze

    2008-01-01

    Nitrogen losses from the soil-plant system may be influenced by herbicide applications. In order to evaluate N loss in brachiaria (Brachiaria decumbens) after application of the herbicides glyphosate and glufosinate-ammonium, an experiment was carried out in a greenhouse as a completely randomized design, with three treatments and six replicates. Treatments were as follows: i) desiccation of brachiaria-plants with glyphosate; ii) desiccation of brachiaria-plants with glufosinate-ammonium; and...

  8. Growth and bromatological characteristics of Brachiaria decumbens and Brachiaria ruziziensis under shading and nitrogen

    Directory of Open Access Journals (Sweden)

    Bruna Moscat Faria

    Full Text Available ABSTRACT This study aimed to evaluate the productive and qualitative characteristics of Brachiaria decumbens and Brachiaria ruziziensis subjected to three levels of artificial shading (0, 36 and 54% and four nitrogen (N doses (0; 50; 100 and 150 mg dm-3 soil, using completely randomized design with a factorial scheme 2 x 3 x 4, with three replications. The dry matter production (DMP, the number of tillers per pot, root weight and crude protein (CP and neutral detergent fiber (NDF contents were evaluated. Both grasses responded quadractly to N, but B. ruziziensis presented greater production under the two highest N doses. The tillers density increased with N dose and was reduced under shading. The root weight increased with N dose, linearly in the full sun and quadractly in the shade. The shading and N showed a positive influence on CP contents. For NDF content, was observed reduction with increase of N dose. The NDF content of B. decumbens increased with shading levels; for B. ruziziensis, the greatest value was observed under intermediate shading level. The N fertilization is an important strategy to improve DMP, tillers density and CP content, for both grasses. However, intense shading should be avoided, as it reduces tillering and root weight, which may threat pasture persistence.

  9. Crop–weed competition

    DEFF Research Database (Denmark)

    Gallandt, Eric R.; Weiner, Jacob

    2015-01-01

    importantly, weed density and time of emergence relative to the crop. Practices that (1) reduce the density of weeds, (2) maximise occupation of space or uptake of resources by the crop or (3) establish an early-season size advantage of the crop over the weeds will minimise the competitive effects of weeds...... on crops. Longer term management of crop–weed competition can be achieved through crop rotations, specifically crop sequences that reduce the weed seed bank, and therefore seedling density, and prevent proliferation of perennial weeds. Key ConceptsKey Concepts * Plant growth requires sunlight, water...... an early-season competitive advantage to the crop and (3) maximising resource capture by the crop using competitive species, competitive cultivars, high sowing densities, optimal spatial arrangement, intercropping complimentary species or transplanting....

  10. Aleloquímico produzido pela gramínea forrageira Brachiaria humidicola Allelochemical produced by the forage grass Brachiaria humidicola

    Directory of Open Access Journals (Sweden)

    A.P.S. Souza Filho

    2005-03-01

    Full Text Available Os métodos usuais de controle de plantas daninhas não atendem mais as atuais e futuras exigências da sociedade em relação à preservação dos recursos naturais e da qualidade de vida. Uma alternativa para essa questão seriam os metabólitos secundários produzidos pelas plantas, que apresentam pouco risco para o ambiente e para os interesses da sociedade. Os objetivos deste trabalho foram isolar, identificar e caracterizar a atividade alelopática de substâncias químicas produzidas pela gramínea forrageira Brachiaria humidicola. Analisaram-se os efeitos alelopáticos dos extratos, frações e substâncias isoladas sobre a germinação e o desenvolvimento da radícula das invasoras malícia, fedegoso e mata-pasto, em bioensaios monitorados em períodos de 10 dias, em condições de 25 ºC e fotoperíodo de 12 horas, para a germinação, e 24 horas, para o desenvolvimento da radícula. A partir do extrato hidrometanólico, foi isolado e identificado o ácido p-cumárico. Os efeitos alelopáticos estiveram positivamente relacionados à concentração do ácido, à espécie de planta daninha e à característica da espécie analisada. Comparativamente, fedegoso e malícia se mostraram mais sensíveis aos efeitos alelopáticos. A germinação e o desenvolvimento da radícula do mata-pasto não foram afetados pelo ácido p-cumárico nas concentrações de 1,0 a 8,0 mg L¹. O alongamento da radícula se mostrou mais sensível aos efeitos alelopáticos do ácido pcumárico do que a germinação das sementes.The traditional methods of weed control in cultivated pasture do not meet society's present and future needs of protecting natural resources and life quality. An alternative to this problem could be the use of secondary metabolites produced by plants. These products present few risks to the environment and meet society interests. Therefore, this research was carried out to isolate, identify and characterize the allelopathic activity of

  11. Phytotoxic substance with allelopathic activity in Brachiaria decumbens.

    Science.gov (United States)

    Kobayashi, Ai; Kato-Noguchi, Hisashi

    2015-05-01

    The grass Brachiaria decumbens becomes naturalized and quickly dominant in non-native areas. It was hypothesized that phytotoxic substances of plants may contribute to the domination and invasion of the plants. However, no potent phytotoxic substance has been reported in B. decumbens. Therefore, we searched for phytotoxic substances with allelopathic activity in this species. An aqueous methanol extract of B. decumbens inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), timothy (Phleum pratense) and ryegrass (Lolium multiflorum) seedlings. The extract was then purified using chromatographic methods and a phytotoxic substance with allelopathic activity was isolated and identified by spectral analysis as (6R,9S)-3-oxo-α-ionol. These results suggest that this compound may contribute to the allelopathic effect caused by the B. decumbens extract and may be in part responsible for the invasion and domination of B. decumbens. Two other Brachiaria species, B. brizantha and a Brachiaria hybrid were also confirmed to contain (6R,9S)-3-oxo-α-ionol. Therefore, this compound may play an important role in the phytotoxicity of the Brachiaria species.

  12. Detecting bacterial endophytes in tropical grasses of the Brachiaria ...

    African Journals Online (AJOL)

    Plant-growth-promoting (PGP) bacteria include a diverse group of soil bacteria thought to stimulate plant growth by various mechanisms. Brachiaria forage grasses, of African origin, are perennials that often grow under low-input conditions and are likely to harbour unique populations of PGP bacteria. Three bacterial strains ...

  13. Ecologically sustainable weed management

    DEFF Research Database (Denmark)

    Liebman, Matt; Baraibar, Bàrbara; Buckley, Yvonne

    2016-01-01

    Weed management is a critically important activity on both agricultural and non-agricultural lands, but it is faced with a daunting set of challenges: environmental damage caused by control practices, weed resistance to herbicides, accelerated rates of weed dispersal through global trade, and gre......Weed management is a critically important activity on both agricultural and non-agricultural lands, but it is faced with a daunting set of challenges: environmental damage caused by control practices, weed resistance to herbicides, accelerated rates of weed dispersal through global trade...... to influence learning, decision-making, and actions by farmers and land managers. We offer examples of how these impediments are being addressed in different parts of the world, but note that there is no clear formula for determining which sets of policies, market mechanisms, and educational activities...... will be effective in various locations. Implementing new approaches for weed management will require multidisciplinary teams comprised of scientists, engineers, economists, sociologists, educators, farmers, land managers, industry personnel, policy makers, and others willing to focus on weeds within whole farming...

  14. Weed flora, yield losses and weed control in cotton crop

    OpenAIRE

    Jabran, Khawar

    2016-01-01

    Cotton (Gossypium spp.) is the most important fiber crop of world and provides fiber, oil, and animals meals. Weeds interfere with the growth activities of cotton plants and compete with it for resources. All kinds of weeds (grasses, sedges, and broadleaves) have been noted to infest cotton crop. Weeds can cause more than 30% decrease in cotton productivity. Several methods are available for weed control in cotton. Cultural control carries significance for weed control up to a certain extent....

  15. Weed ecology and population dynamics

    Science.gov (United States)

    A global rise in herbicide resistant weed genotypes, coupled with a growing demand for food produced with minimal external synthetic inputs, is driving producer interest in reducing reliance on herbicides for weed management. An improved understanding of weed ecology can support the design of weed s...

  16. Meiotic analysis in induced tetraploids of Brachiaria decumbens Stapf

    Directory of Open Access Journals (Sweden)

    Carine Simioni

    2011-01-01

    Full Text Available The meiotic behavior of three tetraploid plants (2n=4x=36 originated from somatic chromosome duplication ofsexually reproducing diploid plants of Brachiaria decumbens was evaluated. All the analyzed plants presented abnormalities relatedto polyploidy, such as irregular chromosome segregation, leading to precocious chromosome migration to the poles and micronucleiduring both meiotic divisions. However, the abnormalities observed did not compromise the meiotic products which were characterizedby regular tetrads and satisfactory pollen fertility varying from 61.36 to 64.86%. Chromosomes paired mostly as bivalents indiakinesis but univalents to tetravalents were also observed. These studies contributed to the choice of compatible fertile sexualgenitors to be crossed to natural tetraploid apomicts in the B. decumbens by identifying abnormalities and verifying pollen fertility.Intraespecific crosses should reduce sterility in the hybrids produced in the breeding program of Brachiaria, a problem observedwith the interspecific hybrids produced so far.

  17. INTEGRATION OF MECHANICAL AND CULTURAL CONTROL TREATMENTS TO MANAGE INVASIVE SHRUB Chromolaena odorata AND OTHER WEEDS UNDER DROUGHT CONDITIONS IN PASTURE AREA

    Directory of Open Access Journals (Sweden)

    M. Rusdy

    2013-03-01

    Full Text Available A field experiment was conducted on Chromolaena odorata dominated pasture with the objectives of evaluating efficacy of integrated of mechanical and cultural control on weed suppression and determining botanical composition of plant species after treatment started. The treatments were, T1 slashing of Chromolaena every month, T2 digging up of Chromolanea, and exposed to dry (mulching, T3 digging up of Chromolaena followed by burning, T4 digging up of Chromolaena followed by burning and sowing with Centrosema pubescens and T5 digging up of Chromolaena followed by burning and planting with Brachiaria decumbens. Results of experiment showed that under drought conditions, digging up Chromolaena was very effective in suppressing regrowth of Chromolaena but it was not effective to other weeds. Among treatments, digging out of Chromolaena followed by burning and planting with Brachiaria decumbens was the most effective and slashing of Chromolaena every month was the least effective in suppressing weeds. Botanical composition was shifted with treatments. Stachytarpheta jamaicensis and Chromolaena were the dominant species in monthly slashed Chromolaena plots, Stachytarpheta and Calopogonium muconoides were the dominant species in mulched plots while Mimosa pudica, Brachiaria and Centrosema were the dominant species in burnt plots.

  18. INTEGRATION OF MECHANICAL AND CULTURAL CONTROL TREATMENTS TO MANAGE INVASIVE SHRUB Chromolaena odorata AND OTHER WEEDS UNDER DROUGHT CONDITIONS IN PASTURE AREA

    Directory of Open Access Journals (Sweden)

    M. Rusdy

    2014-10-01

    Full Text Available A field experiment was conducted on Chromolaena odorata dominated pasture with the objectivesof evaluating efficacy of integrated of mechanical and cultural control on weed suppression anddetermining botanical composition of plant species after treatment started. The treatments were, T1slashing of Chromolaena every month, T2 digging up of Chromolanea, and exposed to dry (mulching,T3 digging up of Chromolaena followed by burning, T4 digging up of Chromolaena followed byburning and sowing with Centrosema pubescens and T5 digging up of Chromolaena followed byburning and planting with Brachiaria decumbens. Results of experiment showed that under droughtconditions, digging up Chromolaena was very effective in suppressing regrowth of Chromolaena but itwas not effective to other weeds. Among treatments, digging out of Chromolaena followed by burningand planting with Brachiaria decumbens was the most effective and slashing of Chromolaena everymonth was the least effective in suppressing weeds. Botanical composition was shifted with treatments.Stachytarpheta jamaicensis and Chromolaena were the dominant species in monthly slashedChromolaena plots, Stachytarpheta and Calopogonium muconoides were the dominant species inmulched plots while Mimosa pudica, Brachiaria and Centrosema were the dominant species in burntplots.

  19. Non-chemical weed management

    DEFF Research Database (Denmark)

    Melander, Bo; Liebman, Matt; Davies, Adam S.

    2017-01-01

    Non-chemical weed management covers all management practices that influence weeds except herbicides. This chapter summarises the major achievements in European research, as well as work undertaken in North America. Research groups from both continents have interacted strongly on the topic over...... and in some cases amenity areas as well. Preventive methods reduce weed germination, cultural methods improve crop competition and direct physical weed control reduces weed survival. Non-chemical weed management is mainly adopted in organic crop production, as conventional growers still perceive it as more...

  20. The effect of ensiling and haymaking on the concentrations of steroidal saponin in two Brachiaria grass species

    Science.gov (United States)

    Brachiaria (signalgrass) is now the most widely used tropical grass genus in Central and South America. However, Brachiaria spp. can cause hepatogenous photosensitization in livestock. Steroidal saponins, specifically protodioscin, present in Brachiaria spp. may be responsible for liver injury and s...

  1. Effect of plant spacing and weeding frequency on weed infestation ...

    African Journals Online (AJOL)

    Common bean is an important food and cash crop in eastern Ethiopia. However, its yield is constrained by weeds. Therefore, this study was conducted in 2012 main cropping season at Haramaya and Hirna research fields, eastern Ethiopia, to determine the effect of plant spacing and weeding frequency on weeds, yield ...

  2. Weeds and Wildlife: Perceptions and Practices of Weed Managers

    Directory of Open Access Journals (Sweden)

    Emma H Carlos

    2014-01-01

    Full Text Available Negative impacts of invasive plants or weeds on biodiversity have been well established yet their role in providing key habitats and resources for wildlife has been little understood. Weed removal thus has the potential to adversely affect wildlife but whether this is considered during weed management is poorly known. To determine the extent of this knowledge, we examined the perceptions of weed managers regarding wildlife and weed management in Victoria, Australia. We surveyed 81 weed managers of varying levels of experience from different types of organisations, including state and local government, community groups and private companies. We found 90% of managers had observed wildlife-weed interactions and that most (70% adjusted management programmes to accommodate wildlife. Despite this, few (19% had adopted the recommended practice of combining gradual weed removal with re-vegetation. While management programmes included monitoring of native vegetation, consideration of wildlife monitoring in weed management was rare. This highlights the need for management to better understand and respond to wildlife-weed relationships. If the improvement of wildlife habitat is included in the objectives of weed programmes, as it should be, then wildlife should also be incorporated in project monitoring. This would lead to a greater understanding of the role weeds and their management have in each situation and, ultimately, more informed decision making.

  3. Grass and weed killer poisoning

    Science.gov (United States)

    ... medlineplus.gov/ency/article/002838.htm Grass and weed killer poisoning To use the sharing features on this page, please enable JavaScript. Many weed killers contain dangerous chemicals that are harmful if ...

  4. WEED INTERFERENCE IN EGGPLANT CROPS

    Directory of Open Access Journals (Sweden)

    LUIZ JUNIOR PEREIRA MARQUES

    2017-01-01

    Full Text Available Uncontrolled weed growth interferes with the growth eggplants and crop yields. To control weeds, the main weed species must be identified in crop growing areas and during weed control periods, as weed species might vary in relation to management practices. Therefore, this study aimed to identify the main weed species and determine the periods of weed interference in the eggplant cultivar Nápoli when grown under certain cultural practices, including plant staking and sprout thinning. The experiment was carried out in 2014 using a randomized complete block design, with 3 replications. The treatments consisted of 11 periods of (1 increasing weed control and (2 increasing coexistence of eggplant with weeds from the first day of transplanting (0-14, 0-28, 0-42, 0-56, 0-70, 0-84, 0-98, 0-112, 0-126, 0-140, and up do day 154. Eggplant staking and sprout thinning were performed 42 days after transplanting (DAT. Weed identification and crop yield assessments were performed to determine the Period Before Interference (PBI, Total Period of Interference Prevention (TPIP, and the Critical Period of Interference Prevention (CPIP. The major weeds found in the eggplant cultivar Nápoli were Eleusine indica, Portulaca oleracea, and Cyperus rotundus. Coexistence between the weed community and the eggplant throughout the entire crop production cycle reduced eggplant fruit yield by 78%. The PBI was 29 DAT and the TPIP was 48 DAT, resulting in 19 days of CPIP.

  5. PRINCIPAIS PLANTAS DANINHAS QUE INFESTAM AS CULTURAS DE ALGODÃO, ARROZ, CAFÉ, MILHO, SOJA E PASTAGENS NO ESTADO DE GOIÁS MAIN WEEDS THAT INFEST COTTON, RICE, COFFEE, MAIZE, SOYBEAN, AND PASTURES IN THE GOIÁS STATE

    Directory of Open Access Journals (Sweden)

    Márcia Regina Albertoni

    2007-09-01

    Full Text Available

    No presente trabalho foi realizado o levantamento das plantas daninhas nas culturas de algodão, arroz, café, milho, soja e nas pastagens de Brachiaria decumbens, Hyparrhenia rufa, Panicum maximum e Brachiaria humidicola em 65 municípios de 12 microrregiões do Estado de Goiás, entre janeiro de 1980 e julho de 1981, num total de 275 observações para 59 espécies de plantas daninhas identificadas.

    A survey was made of weeds found in cotton, rice, corn and soybean fields and coffee plantations, and also in pastures composed of the following grasses: Brachiaria decumbens, Hyparrhenia rufa, Panicum maximum and Brachiaria humidicola. The study was carried out between January 1980 and July 1981, in a total of sixty-five counties within twelve micro-regions in the State of Goiás. Fifty-nine of known species of weeds were identified in a total of two-hundred and seventy-nine observations.

  6. Biotechnology in weed control

    Science.gov (United States)

    Biotechnology can be used to enhance the management of weeds in several ways. Crops have been made resistant to herbicides by inserting transgenes that impart herbicide resistance into the plant genome. Glyphosate and glufosinate-resistant crops are commercialized in North America and crops made res...

  7. Tiller diversity on Brachiaria decumbens pasture managed under continuos stocking

    Directory of Open Access Journals (Sweden)

    Manoel Eduardo Rozalino Santos

    2011-01-01

    Full Text Available The experiment was carried out aiming to classify and quantify tiller categories of Brachiaria decumbens cv. Basilisk from different heights found on the same pasture. Four different plant heights (10; 20; 30 and 40 cm living at the same pasture were evaluated. Randomized block design with three replications was used. Tillers were classified according to their stage of development, growth origin, defoliation level and size. The number of vegetative tillers reduced linearly, while the number of reproductive tillers and dead tillers increased linearly according to the plant height. The number of aerial tillers showed a quadratic response in relation to the plant height. The pastures having grasses of 10, 20, 30 and 40 cm in height had respectively 292, 408, 496 and 344 aerial tillers/m2. The population density of defoliated tillers reduced linearly according to the plant height. The population density of tillers without the apical shoot showed quadratic response to the signal grass height, being the smallest values found for places having grasses of 10 cm (176 tillers/m2 and 40 cm (180 tillers/m2 in height. The number of tillers without defoliation quadratic responded to the plant height, being the highest values found for places having grasses extremely high. The areas with the highest grasses also showed the highest numbers of tallest tillers. There is indeed a spatial variability of the vegetation and a high morphological diversity of tillers on Brachiaria decumbens cv. Basilisk pastures managed under the continuous stocking system.

  8. Weed Dynamics and Management in Wheat

    DEFF Research Database (Denmark)

    Jabran, Khawar; Mahmood, Khalid; Melander, Bo

    2017-01-01

    ) chemical weed control; and (vi) integrated weed management strategy in wheat. A critical analysis of recent literature indicated that broadleaved weeds are the most common group of weeds in wheat fields followed by grass weeds, while sedges were rarely noted in wheat fields. Across the globe, the most...

  9. Weed Identification and Control in Vegetable Crops.

    Science.gov (United States)

    Ferretti, Peter A., Comp.

    This agriculture extension service publication from Pennsylvania State University examines weed control and identification in vegetable crops. Contents include: (1) Types of weeds; (2) Reducing losses caused by weeds, general control methods and home garden weed control; (3) How herbicides are used; (4) Specific weeds in vegetable plantings; and…

  10. INTEGRATED WEED CONTROL IN MAIZE.

    Science.gov (United States)

    Latré, J; Dewitte, K; Derycke, V; De Roo, B; Haesaert, G

    2015-01-01

    Integrated pest management has been implemented as a general practice by EU legislation. As weed control actually is the most important crop protection measure in maize for Western Europe, the new legislation will have its impact. The question is of course which systems can be successfully implemented in practice with respect to labour efficiency and economical parameters. During 3 successive growing seasons (2007, 2008, 2009) weed control in maize was evaluated, the main focus was put on different techniques of integrated weed control and was compared with chemical weed control. Additionally, during 4 successive growing seasons (2011, 2012, 2013 and 2014) two objects based on integrated weed control and two objects based on mechanical weed control were compared to about twenty different objects of conventional chemical weed control. One of the objects based on mechanical weed control consisted of treatment with the flex-tine harrow before and after emergence in combination with chemical weed control at a reduced rate in 3-4 leave stage. The second one consisted of broadcast mechanical treatments before and after emergence followed by a final in-row application of herbicides and an inter-row cultivation at 6-7(8) leave stage. All trials were conducted on the Experimental farm of Bottelare HoGent-UGent on a sandy loam soil. Maize was growing in 1/3 crop rotation. The effect on weed growth as well as the economic impact of the different applications was evaluated. Combining chemical and mechanical weed control is a possible option in conventional farming but the disadvantages must be taken into account. A better planned weed control based on the real present weed-population in combination with a carefully thought-out choice of herbicides should also be considered as an IPM--approach.

  11. WeedML: a Tool for Collaborative Weed Demographic Modeling

    OpenAIRE

    Holst, Niels

    2010-01-01

    WeedML is a proposed standard to formulate models of weed demography, or maybe even complex models in general, that are both transparent and straightforward to re-use as building blocks for new models. The paper describes the design and thoughts behind WeedML which relies on XML and object-oriented systems development. Proof-of-concept software is provided as open-source C++ code and executables that can be downloaded freely.

  12. Robotic weed monitoring

    DEFF Research Database (Denmark)

    Bochtis, Dionysis; Sørensen, Claus Aage Grøn; Jørgensen, R N

    2011-01-01

    Abstract: In this paper, an integrated management system for the planning and activation of thefield monitoring task is presented. The architecture of the system is built around a mobile roboticunit. The internet based architecture of the system includes a station unit that works as a mobileon-fa...... of the weed monitoring operation.Key words: autonomous vehicles, farm management, mission planning, route planning,sampling....

  13. Nitrogen balance in grasses of the genus Brachiaria

    International Nuclear Information System (INIS)

    Loureiro, M. de F.

    1985-01-01

    A 15 N aided nitrogen balance experiment was performed in posts in the greenhouse to quantify the contribution of biological nitrogen fixation to four species of Brachiaria grow in two soils. The effects of adding molybdenum to the pots was also investigated. Among various methods for the analysis of total nitrogen in plant material and soil, a technique utilizing a pre-digestion with Devarda's alloy was found to be most efficient. In the nitrogen analyses the sample size and particle size were found to be factors limiting the precision of the analyses. In an analysis of the sources of error, the sampling of the soil was found to be the greatest source of variation on the nitrogen balance. (author)

  14. Selective weed control using laser techniques

    OpenAIRE

    Marx, Christian; Pastrana-Perez, Julio; Hustedt, Michael; Barcikowski, Stephan; Haferkamp, Heinz; Rath, Thomas

    2012-01-01

    This contribution discusses technical and growth relevant aspects of using laser techniques for weed control. The research on thermal weed control via laser first focused on the interaction of laser beams and weed plants. Due to preliminary studies, a CO2-laser was selected for further studies with regard to the process factors laser energy, laser spot area, coverage of the weeds meristem, weed species (Amaranthus retroflexus), and weed growth stage. Thereby, the laser damage was modeled in o...

  15. Effect of ploughing frequency and weeding methods on weeds and ...

    African Journals Online (AJOL)

    User

    Five tillage practices ... 2.5 l ha-1, Duplosan plus one hand weeding at 30 days after emergence (DAE); ... weed on time, is one of the major constraints in wheat ... management factors and soil type (Yohannes, 1982). .... The finding at ICARDA (1984) shows that ..... selling price of the crop changes, the farmer can still get a.

  16. Consórcio de milho e Brachiaria decumbens em diferentes preparos de solo = Maize and Brachiaria decumbens under different soil tillage in farmingpasture integration

    Directory of Open Access Journals (Sweden)

    Simério Carlos Silva Cruz

    2009-10-01

    Full Text Available Preparos conservacionistas e sistemas de produção que visam à maximização sustentável do uso do solo e da água têm surgido como alternativas para regiões caracterizadas por períodos chuvosos relativamente curtos e temperaturas elevadas. O objetivo deste trabalho foi avaliar o sistema de consorciação entre milho e Brachiaria decumbens que melhor se adapte às condições dafoclimáticas da região da Zona da Mata do Estado de Alagoas. Os tratamentos consistiram de um híbrido de milho BRS3150, cultivado nos sistemas: Preparo Convencional, Cultivo Mínimo e Semeadura Direta (BRS3150consorciado com Brachiaria decumbens. O delineamento utilizado foi o de blocos casualisados com parcelas subdivididas. Amostras de solo foram coletadas para análise química. Também foram avaliados os componentes da produção e produtividade de grãos de milho. Os diferentes preparos do solo e a presença de Brachiaria decumbens, no sistema de consócio com milho, não exerceram influência sobre os componentes da produção. Os resultados analisados permitem concluir que a presença da Brachiaria decumbens interferiu negativamente na produtividade dos grãos de milho, quando cultivado em sistema deconsórcio, e as maiores produtividades foram obtidas nos sistemas conservacionistas.Conservation tillage and production systems that aim to maximize soiland water use in a sustainable form have become alternatives for regions that have relatively short periods of rain and high temperatures. The objective of this research was to evaluate intercropping systems with maize and Brachiaria that have better adaptation to the edaphoclimatic conditions of the “Zona da Mata” region, state of Alagoas. The treatments consisted of a BRS 3150 hybrid of maize, cultivated in the following systems: Conventional Cropping, Minimum Cultivation and No-tillage (BRS 3150 intercropped with Brachiaria decumbens. The design used was randomized block with subdivided plots. Soil

  17. Site-specific weed control technologies

    DEFF Research Database (Denmark)

    Christensen, Svend; Søgaard, Henning Tangen; Kudsk, Per

    2009-01-01

    Site-specific weed control technologies are defined as machinery or equipment embedded with technologies that detect weeds growing in a crop and, taking into account predefined factors such as economics, takes action to maximise the chances of successfully controlling them. In the article, we...... describe the basic parts of site specific weed control technologies, comprising of weed sensing systems, weed management models and precision weed control implements. A review of state-of-the-art technologies shows that several weed sensing systems and precision implements have been developed over the last...... of knowledge about the economic and environmental potential for increasing the resolution of weed control. The integration of site-specific information on weed distribution, weed species composition and density, and the effect on crop yield, is decisive for successful site-specific weed management.   Keywords...

  18. Spatial analysis of weed patterns

    NARCIS (Netherlands)

    Heijting, S.

    2007-01-01

    Keywords: Spatial analysis, weed patterns, Mead’s test, space-time correlograms, 2-D correlograms, dispersal, Generalized Linear Models, heterogeneity, soil, Taylor’s power law. Weeds in agriculture occur in patches. This thesis is a contribution to the characterization of this patchiness, to its

  19. PRODUÇÃO E COMPOSIÇÃO QUÍMICA DA Brachiaria brizantha E Brachiaria decumbens SUBMETIDAS A DIFERENTES ADUBAÇÕES PRODUCTION AND CHEMICAL COMPOSITION OF Brachiaria brizantha AND Brachiaria decumbens SUBMITTED TO DIFFERENT FERTILIZATION

    Directory of Open Access Journals (Sweden)

    Neusete Maria da Silva Patês

    2008-12-01

    Full Text Available Objetivou-se, com este trabalho, avaliar a produção e a composição química de dois cultivares de braquiária com diferentes adubações. Instalou-se o experimento em casa de vegetação no Campus Juvino Oliveira pertencente à UESB, localizado na cidade de Itapetinga, BA. O ensaio foi desenvolvido em esquema fatorial 2x5, sendo dois cultivares de Brachiaria (B. brizantha cv. marandu e B. decumbens cv. basilisk e cinco adubações (sem adubo, N, P, NP e NK, mediante a utilização de 50 kg.ha-1 de P, 30 kg.ha-1 de K e 300 kg.ha-1 de N como nutrientes. O delineamento adotado foi inteiramente ao acaso, com quatro repetições. Utilizaram-se vasos plásticos com 30 cm de diâmetro por 22 cm de altura e capacidade de 10 dm3. Efetuaram-se três coletas de amostras da parte aérea, sendo cada período correspondente a 28 dias de crescimento da planta. Procedeu-se à coleta dessas amostras e secagem destas em estufa, sendo depois moídas a 1 mm. Posteriormente, fez-se uma amostra composta. Os resultados demonstram que a interação entre os cultivares e a adubação foi significativa para produção de massa seca da parte aérea e cinzas. O cultivar basilisk mostrou-se superior em relação ao cultivar marandu na maioria das variáveis analisadas. Os valores encontrados para a composição química dos cultivares em estudo estão de acordo com os valores tabelados para gramíneas com rebrota de 28 dias.

    PALAVRAS-CHAVES: Baquiária, proteína bruta, raízes. The objective of this work was to evaluate the production and chemical composition of two cultivates of Brachiaria with different fertilizations. The experiment was installed in a green house at Juvino Oliveira Campus of UESB, in Itapeting, BA. The assay was conducted in a 2x5 factorial scheme, being two cultivates of Brachiaria (B. brizantha cv. marandu and B. decumbens cv. basilisk and five fertilizations (without fertilizer, P, N, NP and NK. The quantity of nutrients used was 50 kg

  20. 7 CFR 201.15 - Weed seeds.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Weed seeds. 201.15 Section 201.15 Agriculture... REGULATIONS Labeling Agricultural Seeds § 201.15 Weed seeds. The percentage of weed seeds shall include seeds of plants considered weeds in the State into which the seed is offered for transportation or...

  1. Applicator Training Manual for: Aquatic Weed Control.

    Science.gov (United States)

    Herron, James W.

    The aquatic weeds discussed in this manual include algae, floating weeds, emersed weeds, and submerged weeds. Specific requirements for pesticide application are given for static water, limited flow, and moving water situations. Secondary effects of improper application rates and faulty application are described. Finally, techniques of limited…

  2. Controle de Brachiaria subquadripara e Brachiaria mutica através de diferentes herbicidas aplicados em pós-emergência Control of Brachiaria subquadripara and Brachiaria mutica by different herbicides applied post-emergence

    Directory of Open Access Journals (Sweden)

    C.A. Carbonari

    2003-01-01

    Full Text Available Foram realizados dois experimentos, com objetivo de avaliar a suscetibilidade de Brachiaria subquadripara e Brachiaria mutica a diferentes herbicidas aplicados em pósemergência. Os herbicidas e doses testados foram: glyphosate (Rodeo a 2.400, 3.360 e 4.320 g e.a. ha-1 com Aterbane a 0,5% v/v; glyphosate a 2.400, 3.360 e 4.320 g e.a. ha-1 com Silwet a 0,1% v/v; imazapyr (Arsenal a 750 e 1.500 g e.a. ha-1; e diquat (Reward a 400 e 800 g i.a. ha-1 com aplicação seqüencial. Manteve-se uma testemunha sem aplicação de herbicidas. As parcelas experimentais foram constituídas de caixas d'água de 60 x 60 x 45 cm, com 55 L de solo. A aplicação foi realizada quando as plantas se encontravam a 45 e 65 cm de altura para B. subquadripara e B. mutica, respectivamente. Foi utilizado um pulverizador costal, a pressão constante de CO2 (2 bars, pontas 110.02 XR, com um consumo de calda de 200 L ha-1. O controle foi avaliado visualmente, através de escala percentual de notas, além de se avaliar a massa seca das plantas. O herbicida glyphosate nas doses de 3.360 e 4.320 g e.a. ha-1, independentemente do adjuvante testado, proporcionou controle excelente para as duas espécies, porém as parcelas que receberam glyphosate a 2.400 g e.a. ha-1 apresentaram controle apenas satisfatório. O herbicida imazapyr nas doses de 750 e 1.500 g e.a. ha-1 proporcionou controle eficiente para B. subquadripara e excelente para B. mutica. Já o herbicida diquat, apesar de duas aplicações e independentemente da dose utilizada, mostrou-se ineficiente no controle das duas espécies.Two experiments were carried out to evaluate the susceptibility of Brachiaria subquadripara and Brachiaria mutica to different herbicides applied in post-emergence. The herbicides and doses used were: glyphosate (Rodeo at 2,400, 3,360 and 4,320 (g a.e. ha-1 plus Aterbane 0.5% v/v; glyphosate at 2,400, 3,360 and 4,320 (g a.e. ha-1 plus Silwet 0.1% v/v; imazapyr (Arsenal at 750 and 1,500 (g a

  3. Perfil químico da parede celular e suas implicações na digestibilidade de Brachiaria brizantha e Brachiaria humidicola Chemical profile of cell wall and its implications on Brachiaria brizantha and Brachiaria humidicola digestibility

    Directory of Open Access Journals (Sweden)

    Cláudio José F. Alves de Brito

    2003-12-01

    Full Text Available No presente trabalho foram determinadas a composição química e a digestibilidade de diversas frações de Brachiaria brizantha e Brachiaria humidicola, após 70 dias de crescimento. O delineamento experimental foi inteiramente casualizado com cinco repetições para cada espécie. As plantas coletadas foram subdivididas nas frações apical, mediana e basal para as folhas e mediana e basilar para caules, de acordo com sua localização. Foram determinadas as concentrações de fibra em detergente neutro (FDN, proteína bruta (PB, lignina, ácido p_cumárico, ácido ferúlico e açúcares neutros (glicose, xilose e arabinose e a digestibilidade in situ após 48 horas de período de incubação ruminal. As diferentes frações das espécies estudadas apresentam distinta composição química, cujos efeitos são observados na digestibilidade. A B. brizantha apresentou maiores concentrações de FDN no caule e PB nas folhas. Isto resultou em coeficientes de digestibilidade maiores em relação à B. humidicola. A diferença de digestibilidade entre caule e folhas e nas frações mais velhas pode estar relacionada ao tipo de condensação da lignina presente nos tecidos. Evidências na concentração e na proporção dos ácidos p_cumárico e ferúlico sugerem esta relação. A concentração de ácidos fenólicos esteve relacionada com a digestibilidade da matéria seca e a lignina com a digestibilidade da FDN. A análise dos ácidos fenólicos pode se constituir em importante ferramenta para avaliar o grau de condensação da lignina na parede celular dos diferentes tecidos das plantas forrageiras. A concentração de açúcares neutros não apresentou um padrão definido na composição dos diferentes tecidos. A arabinose foi o único açúcar que apresentou relações com a digestibilidade da matéria seca e com a concentração de ácidos fenólicos.In the present paper the chemical composition and digestibility of several Brachiaria

  4. Perdas de nitrogênio por Brachiaria decumbens após a aplicação de glifosato ou glufosinato de amônio

    OpenAIRE

    DAMIN, Virginia; FRANCO, Henrique Coutinho Junqueira; MORAES, Milton Ferreira; FRANCO, Ademir; TRIVELIN, Paulo Cesar Ocheuze

    2008-01-01

    Nitrogen losses from the soil-plant system may be influenced by herbicide applications. In order to evaluate N loss in brachiaria (Brachiaria decumbens) after application of the herbicides glyphosate and glufosinate-ammonium, an experiment was carried out in a greenhouse as a completely randomized design, with three treatments and six replicates. Treatments were as follows: i) desiccation of brachiaria-plants with glyphosate; ii) desiccation of brachiaria-plants with glufosinate-ammonium; and...

  5. of different weed control methods on Weed infestation, growth

    African Journals Online (AJOL)

    thinkexploitsint'l

    This weed control method also resulted in significantly better growth and ... proper management, it is possible to obtain 2,500 kg ha-1 (Onwueme and Sinha, 1991). ... however, time consuming, labour – intensive, strenuous and generally ...

  6. Ecological Weed Management by Cover Cropping: Effect on Winter Weeds and Summer Weeds Establishment in Potato

    Directory of Open Access Journals (Sweden)

    M Ghaffari

    2012-07-01

    Full Text Available Now a day winter cover crops planting has been attended to reduce herbicide application. An experiment was carried out at the Research Farm of Agriculture Faculty, Bu- Ali Sina, University, in 2009. The experiment was a randomized complete block design with three replications. The trial included of five treatments consists of no cover crop, rye, winter oilseed rape, barley and triticale. The results showed that winter cereals were produced more biomass than winter oilseed rape. living mulch of rye, barley, oilseed rape and triticale reduced winter weeds biomass 89, 86, 82 and 70 percent respectively, in compare to control. Cover crop treatments showed significant different weeds control of potato at 3 time (15, 45 and 75 DAPG compare to control treatment. Residues mixed to soil of oilseed rape and rye had the most inhibition affects on summer weeds. These treatments, average weeds biomass decreased 61 and 57 percent respectively, in compare to control. Oilseed rape and rye in compare to control reduced weeds density in potato 36 and 35 percent, respectively. Significant negation correlations of weeds plant population, weeds dry matter with average tuber weight and potato yield. The treatments, oilseed rape and rye in compare to control increased tuber yield of potato 54 and 50 percent, respectively. These treatments, the average tuber weight increased 74 and 38 percent in compare with control, respectively.

  7. Weather and plant age affect the levels of steroidal saponin and Pithomyces chartarum spores in Brachiaria grass

    Science.gov (United States)

    Brachiaria species are cultivated worldwide in tropical and subtropical climates as the main forage source for ruminants. Numerous tropical and warm-season grasses cause hepatogenous photosensitization, among them several species of Brachiaria. Steroidal saponins present in these plants may be respo...

  8. Weed clearance in Hudiara Nallah by chemical weed control

    International Nuclear Information System (INIS)

    Dhillon, G.S.

    1981-01-01

    Hudiara Nallah is a flood stream in West Punjab. It has a length of about 45km and breadth of nearly 25 metres. About 20 subsidiary drains join with the Nallah. These drains have a length of about 270km. The Nallah has a discharge capacity of 1248 cusecs. Most of the subsidiary drains start from ponds which are generally infected with Eichhornia plants. These plants enter into the subsidiary drains and finally into Hudiara Nallah. The plants float freely on the surface of water and multiply at a high rate. One plant of the weed propagates to 24 plants in a period of one month. The plants thus cover the whole drain in a few months. The weed also originates from seeds. Their heavy growth forms a mat-like surface. The weeds also choke bridges and sometimes cause damage to their structures. These obstruct the flow of water and decrease the carrying capacity of the drain. Their infestation thus causes floods and the very purpose of the drains gets lost. Thus the Nallah is heavily infested with Eichhornia crassipes (water hyacinth weed). Due to its fast propagation and heavy infestation it was not possible to clear the weed manually. The problem was, therefore, referred to the Chemistry Division of the Irrigation and Power Research Institute, Amritsar, by the Drainage Circle of the Irrigation Department in June 1978 when weed propagation was in full swing. A chemical treatment method of eradication was attempted

  9. Interferência e nível de dano econômico de Brachiaria plantaginea e Ipomoea nil na cultura do feijão comum Interference and economic threshold of Brachiaria plantaginea and Ipomoea nil in the common bean crop

    Directory of Open Access Journals (Sweden)

    Ribas Antonio Vidal

    2010-08-01

    Full Text Available As pesquisas acerca do impacto da interferência das plantas daninhas sobre as culturas normalmente são realizadas com uma única espécie infestante, quando na realidade podem ocorrer diversas. Os objetivos deste trabalho foram avaliar a interferência de Brachiaria plantaginea e Ipomoea nil sobre o rendimento de grãos do feijoeiro (Phaseolus vulgaris e determinar o nível de dano econômico (NDE de cada espécie na cultura. Foram realizados dois experimentos a campo com as cultivares de feijão 'IPR Graúna' (Grupo Preto e 'UTF-06' (Grupo Carioca em convivência com infestações mistas em diferentes proporções aleatórias das espécies B. plantaginea e I. nil. Modelos de regressão múltiplos foram utilizados para determinar a capacidade de interferência de cada espécie daninha sobre a produtividade da cultura. O impacto de interferência de cada planta de I. nil correspondeu a 2,6 e 0,25 quando comparada a cada planta de B. plantaginea, dependente das proporções relativas na comunidade infestante e das condições de cada experimento. A cultivar 'IPR Graúna' apresentou maior habilidade competitiva do que 'UTF-06'. O NDE foi dependente da proporção relativa de cada espécie daninha na comunidade e foi obtido sob baixas infestações (The researches about the impact of weed interference on crops are usually performed with a single weed species, when in reality there are numerous. The objective of this study was to evaluate the interference of Brachiaria plantaginea and Ipomoea nil on the grain yield of French beans (Phaseolus vulgaris and to determine the economic weed threshold (EWT of each species on the crop. Two field experiments were conducted with bean cultivars 'IPR Graúna' (Black group and 'UTF-06' (Carioca group in coexistence with random proportions of mixed infestations of B. plantaginea and I. nil. Multiple regression models were used to determine the interference abi1lity of each weed species on crop productivity. The

  10. Intoxicação natural por Brachiaria spp. em ovinos no Brasil Central Brachiaria spp. poisoning in sheep in Central Brazil

    Directory of Open Access Journals (Sweden)

    Vanessa S. Mustafa

    2012-12-01

    Full Text Available Brachiaria spp. é a principal forrageira utilizada para ruminantes no Brasil Central, mas a sua toxicidade, devida à presença de saponinas esteroidais, torna-se um importante entrave à sua utilização. Neste trabalho descrevem-se 34 surtos e um foco de intoxicação por Brachiaria spp em ovinos, que ocorreram em diferentes épocas do ano. A morbidade geral foi de 23,2% e a letalidade foi 88,3%. O tempo que os animais permaneceram no pasto até o surgimento dos sinais clínicos da intoxicação por Brachiaria spp. variou de 15 dias até mais de 12 meses. Em 90,1% dos surtos os animais eram menores de 12 meses de idade. O curso clínico da intoxicação variou de 2 a 45 dias. Os sinais clínicos e as lesões macroscópicas foram características de fotossenssibilização hepatógena, no entanto, nos casos mais agudos não foram observadas dermatite nem icterícia, ocorrendo severo edema em face e orelhas. Na histologia do fígado as lesões mais características foram a presença de macrófagos com citoplasma espumoso, encontrados principalmente nos sinusoides hepáticos e, às vezes, com imagens negativas de cristais acutiformes no citoplasma. Em oito das 11 fazendas visitadas os surtos ocorreram em pastagens de Brachiaria decumbens; em duas em pastagens de B. brizantha e uma em pastagem de B. decumbens, B. humidicola e Andropogon sp. As concentrações de saponinas nas pastagens, em 5 surtos, variou de 0.3% a 2.56%. As informações geradas neste trabalho permitem a proposta de medidas para controle e profilaxia da intoxicação por Brachiaria spp. no Brasil Central.Brachiaria spp. is the main pasture for ruminants in Central-Brazil, but the crucial problem for their utilization is the toxicity due to the presence of steroidal saponins. This paper reports 35 outbreaks of poisoning by Brachiaria spp in sheep. The poisoning occurred in different seasons of the year. Mean morbidity was 23.2% and mean lethality was 88.3%. The occurrence of

  11. Integrated weed management in wheat

    International Nuclear Information System (INIS)

    Marwat, K.B.; Khan, M.A.; Nawab, K.; Khattak, A.M.

    2011-01-01

    The paper summarizes the results of an experiment conducted on wheat at Kohat, Khyber Pakhtunkhwa, Pakistan during winter 2004-05. Randomized complete block design with split-split-plot arrangement was used where wheat line and broadcast sowing were kept in main plots. Seed rates (100 and 150 kg ha-1) were assigned as sub-plots, while four herbicides (Topik, Isoproturon, Puma super and Buctril super) and weed check were assigned to sub-sub-plots. Results revealed that higher biological yield was recorded in line sowing. However, higher wheat seed rate decreased weed biomass and increased biological yield. Herbicides proved to be effective in decreasing weed biomass and enhancing grain yield and its contributing traits. It was suggested that line sowing in combination with higher seeding rate and Buctril super should be used in an integrated weed management fashion. However further studies are required to investigate various ranges of seeding rate and herbicides doses. (author)

  12. Can global weed assemblages be used to predict future weeds?

    Directory of Open Access Journals (Sweden)

    Louise Morin

    Full Text Available Predicting which plant taxa are more likely to become weeds in a region presents significant challenges to both researchers and government agencies. Often it is done in a qualitative or semi-quantitative way. In this study, we explored the potential of using the quantitative self-organising map (SOM approach to analyse global weed assemblages and estimate likelihoods of plant taxa becoming weeds before and after they have been moved to a new region. The SOM approach examines plant taxa associations by analysing where a taxon is recorded as a weed and what other taxa are recorded as weeds in those regions. The dataset analysed was extracted from a pre-existing, extensive worldwide database of plant taxa recorded as weeds or other related status and, following reformatting, included 187 regions and 6690 plant taxa. To assess the value of the SOM approach we selected Australia as a case study. We found that the key and most important limitation in using such analytical approach lies with the dataset used. The classification of a taxon as a weed in the literature is not often based on actual data that document the economic, environmental and/or social impact of the taxon, but mostly based on human perceptions that the taxon is troublesome or simply not wanted in a particular situation. The adoption of consistent and objective criteria that incorporate a standardized approach for impact assessment of plant taxa will be necessary to develop a new global database suitable to make predictions regarding weediness using methods like SOM. It may however, be more realistic to opt for a classification system that focuses on the invasive characteristics of plant taxa without any inference to impacts, which to be defined would require some level of research to avoid bias from human perceptions and value systems.

  13. Recovery of degraded pasture in Rondônia: macronutrients and productivity of brachiaria brizantha Recuperação de pastagem degradada em Rondônia: macronutrientes e produtividade da brachiaria brizantha

    Directory of Open Access Journals (Sweden)

    Norberto Cornejo Noronha

    2010-10-01

    Full Text Available Pasture is the main form of land use in Amazonia. Over time the pasture grass loses vigor and yields decrease, indicating a certain degree of degeneration. The main causes of degradation are lack of pasture maintenance and subsequent weed infestation, the choice of regionally unsuitable forage species and excessive grazing. The main purpose of this study was to evaluate the impact of different recovery managements on soil chemical properties and grass yield of a degraded pasture in Rondônia. For this purpose, an experiment was installed in October 2001, consisting of five treatments: C = control; HA = harrowing + NPK + micronutrients; HE = Herbicide + NK + micronutrients; R = No-tillage rice + NPK + micronutrients; and S = No-tillage soybean + PK + micronutrients. The following N, P and K sources were used: ammonium sulfate for N, calcined phosphate for P and potassium chloride for K. The experiment was arranged in a randomized block design with four replications. The shoot dry matter yield of the grass was analyzed as of the 35th month of experimentation, in a dry and a rainy period. Phosphorus fertilization resulted in significant increases in Ca2+ and Mg2+ and increasing trend of P in the topsoil in the initial months of the experiment in treatments HA and S and increases in Ca2+ and P (trend in the treatment R. The cumulative production of Brachiaria brizantha, from Sep/2004 to Mar/2005, was 30,025, 28,267 and 27,735 kg ha-1 shoot dry matter in the treatments HA, R and S, respectively. These values differed significantly from treatments C and HE, with 17,040 and 17,057 kg ha-1, respectively. It was concluded that phosphorus fertilization associated to pasture reform was effective to raise the dry matter yield of Brachiaria brizantha. Rice or soybean under no-tillage is recommended as a practice of pasture recovery, due to the residual effect of fertilization.As pastagens consistem no principal uso da terra na Amazônia. Com o tempo de

  14. 7 CFR 201.50 - Weed seed.

    Science.gov (United States)

    2010-01-01

    ... REGULATIONS Purity Analysis in the Administration of the Act § 201.50 Weed seed. Seeds (including bulblets or... sieve are considered weed seeds. For wild onion and wild garlic (Allium spp.) bulblets classed as inert...

  15. Acúmulo de forragem em pastos de Brachiaria decumbens adubados com nitrogênio Biomass of the forage in Brachiaria decumbens pastures fertilized with nitrogen

    Directory of Open Access Journals (Sweden)

    Jailson Lara Fagundes

    2005-04-01

    Full Text Available A dinâmica de crescimento de plantas forrageiras tem sido foco de estudo nos últimos anos, visando aprimorar o conhecimento do processo de produção de forragem em pastagens. O objetivo deste trabalho foi avaliar o acúmulo de forragem em pastos de Brachiaria decumbens Stapf. adubados com nitrogênio e submetidos a uma mesma intensidade de pastejo. Os tratamentos consistiram de 75, 150, 225 e 300 kg ha-1 ano-1 de N, aplicados antes do início das avaliações experimentais, as quais foram realizadas durante as estações de verão, outono, inverno e primavera de 2002. O delineamento experimental utilizado foi o de blocos completos casualizados com duas repetições. O capim-braquiária apresentou incremento de produção de matéria seca proporcional às doses de nitrogênio. Observaram-se maiores valores de taxa de acúmulo de folha, colmo e forragem nas estações primavera-verão e valores menores no inverno. As variações nas condições climáticas com as estações do ano alteraram as taxas de acúmulo de folha e colmo, senescência e de produção de forragem em Brachiaria decumbens.In the last years, the growth dynamics of forage plants has been focused, in order to improve the knowledge of forage yield and distribution process in pasture. The objective of this work was to evaluate the effect of nitrogen fertilization on accumulation of the forage in Brachiaria decumbens Stapf. pastures submitted to the same stocking rate. Treatments consisted of 75, 150, 225 and 300 kg ha-1 yr-1 N applied before the beginning of experimental evaluations, which were performed during summer, autumn, winter and spring of 2002. A randomized block experimental design was used with two replicates. Brachiaria grass showed an increase in the dry matter yield proportionally to nitrogen doses, with higher rates for daily accumulation of leaves, stems and forage yield in summer-spring seasons, while lower rates were shown in the winter. The variation of

  16. Prospects for site specific weed management

    DEFF Research Database (Denmark)

    Christensen, Svend; Rasmussen, Jesper; Pedersen, Søren Marcus

    2014-01-01

    Research on Site Specific Weed Management (SSWM) started in the late 80's. Since that moment, considerable research has been conducted on different aspects of SSWM, from fundamental studies on the spatial ecology of weeds to the applied development and testing of new technologies for weed detection...

  17. Weed Recognition Framework for Robotic Precision Farming

    DEFF Research Database (Denmark)

    Kounalakis, Tsampikos; Triantafyllidis, Georgios; Nalpantidis, Lazaros

    2016-01-01

    using advanced encoding and machine learning algorithms. The resulting system can be applied in a variety of environments, plantation or weed types. This results in a novel and generic weed control approach, that in our knowledge is unique among weed recognition methods and systems. For the experimental...

  18. Molecular Characterizations of Kenyan Brachiaria Grass Ecotypes with Microsatellite (SSR Markers

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    Naftali Ondabu

    2017-02-01

    Full Text Available Brachiaria grass is an emerging forage option for livestock production in Kenya. Kenya lies within the center of diversity for Brachiaria species, thus a high genetic variation in natural populations of Brachiaria is expected. Overgrazing and clearing of natural vegetation for crop production and nonagricultural uses and climate change continue to threaten the natural biodiversity. In this study, we collected 79 Brachiaria ecotypes from different parts of Kenya and examined them for genetic variations and their relatedness with 8 commercial varieties. A total of 120 different alleles were detected by 22 markers in the 79 ecotypes. Markers were highly informative in differentiating ecotypes with average diversity and polymorphic information content of 0.623 and 0.583, respectively. Five subpopulations: International Livestock Research Institute (ILRI, Kitui, Kisii, Alupe, and Kiminini differed in sample size, number of alleles, number of private alleles, diversity index, and percentage polymorphic loci. The contribution of within‐the‐individual difference to total genetic variation of Kenyan ecotype population was 81%, and the fixation index (FST = 0.021 and number of migrant per generation (Nm = 11.58 showed low genetic differentiation among the populations. The genetic distance was highest between Alupe and Kisii populations (0.510 and the lowest between ILRI and Kiminini populations (0.307. The unweighted neighborjoining (NJ tree showed test ecotypes grouped into three major clusters: ILRI ecotypes were present in all clusters; Kisii and Alupe ecotypes and improved varieties grouped in clusters I and II; and ecotypes from Kitui and Kiminini grouped in cluster I. This study confirms higher genetic diversity in Kenyan ecotypes than eight commercial varieties (Basilisk, Humidicola, Llanero, Marandú, MG4, Mulato II, Piatá and Xaraés that represent three species and one three‐way cross‐hybrid Mulato II. There is a need for further

  19. Intercropping of corn, brachiaria grass and leguminous plants: productivity, quality and composition of silages

    Directory of Open Access Journals (Sweden)

    Patrícia Monteiro Costa

    2012-10-01

    Full Text Available The present study was carried out with the objective to evaluate the productive and qualitative characteristics of forages produced in systems of intercropping of corn, brachiaria grass and different leguminous plants. Productivity, bromatological composition and the fermentative profile of the silages from the following treatments were evaluated: corn in exclusive cultivation (CEC; intercropping of corn with brachiaria grass (CB; intercropping of corn, brachiaria grass and Calopogonium mucunoides (CBCal; intercropping of corn, brachiaria grass and Macrotyloma axillare (CBMac; and intercropping of corn, brachiaria grass and Stylozanthes capitata (CBSty. The experimental design utilized was completely randomized. For each type of cultivation, five plots or replications of three linear meters were harvested, and the material was separated. The variables assessed were: dry matter productivity per area; dry matter productivity of corn per area; crude protein production per area and productivity of total digestible nutrients per area. The material originated from the cultures was ensiled, with dry matter between 28 and 32%. After, the material was placed and compacted appropriately in bucket silos. A sample was collected from each replication for determination of the contents of DM, crude protein (CP, ether extract (EE, lignin, neutral and acid detergent fibers (NDF and ADF and TDN. A fraction of the sample of silages from each treatment was compressed for extraction of the juice and determination of the silage quality. There was difference between the forms of cultivation for the dry matter production per hectare. The CEC with production of 11920.1 kg DM/ha did not differ from CB (8997.41 kg DM/ha or CBCal (10452.10 kg DM/ha; however, it was superior to CBMac (8429.75 kg DM/ha and to CBSty (8164.83 kg DM/ha. The contents of DM, CP, NDF, ADF, lignin and TDN did not differ between the silages from the different treatments. All the silages presented

  20. Disponibilidade de macronutrientes em cultivares de cana-de-açúcar submetidas à competição com Brachiaria brizantha Macronutrients availability in sugarcane varieties grown under increasing densities of Brachiaria brizantha

    Directory of Open Access Journals (Sweden)

    Leandro Galon

    2012-08-01

    Full Text Available Objetivou-se com o trabalho verificar os teores foliares dos macronutrientes e o desenvolvimento das cultivares de cana-açúcar 'RB72454', 'RB867515' e 'SP801816' em competição com populações de Brachiaria brizantha. Os tratamentos utilizados foram: 1 cultivar de cana-de-açúcar 'RB72454' e população de B. brizantha de 0, 1, 3, 7, 15, 32, 40, 32, 64, 92, 88 e 112; 2 'RB867515' e 0, 1, 4, 14, 10, 18, 28, 30, 36, 54, 52 e 72; 3 'SP801816' e 0, 1, 3, 6, 14, 20, 24, 26, 26, 32, 46 e 56 plantas m-2. Aos 120 dias após a emergência da cultura, foi quantificada a massa seca (MS da parte aérea da cana-de-açúcar e da B. brizantha. Aos 290 dias após a emergência (DAE, foram coletadas amostras das folhas +3 (terceira folha a partir do ápice das plantas, nas quais foram avaliadas as concentrações de nitrogênio total, fósforo, potássio, magnésio e cálcio. Com o aumento da população de B. brizantha, observou-se redução da MS somente na cultivar 'RB72454'. O aumento na população de B. brizantha reduziu a concentração de fósforo em todas as cultivares, nitrogênio em 'RB72454' e 'SP801816', potássio e magnésio para 'RB72454'. Nas populações mais elevadas de B. brizantha, houve maior competição pelos nutrientes disponíveis no meio, sendo o fósforo o mais limitante. A cultivar 'RB72454' foi a menos competitiva pelos nutrientes no solo. As cultivares apresentaram redução média de 76% na produtividade de colmos na densidade máxima de B. brizantha.This trial aimed to verify foliar levels of macronutrients and development of sugarcane cultivars 'RB72454', 'RB867515' and 'SP801816' under competition with populations of Brachiaria brizantha. The field trial was installed where treatments were: 1 Sugarcane 'RB72454' and B. brizantha population of 0, 1, 3, 7, 15, 32, 40, 32, 64, 92, 88 e 112; 2 'RB867515' e 0, 1, 4, 14, 10, 18, 28, 30, 36, 54, 52 e 72; 3 'SP801816' e 0, 1, 3, 6, 14, 20, 24, 26, 26, 32, 46 e 56 plants m-2. At 120

  1. Avaliação de angustifoliadicidas na cultura da soja em Minas Gerais Grass weed control with herbicides in soybeans in Minas Gerais

    Directory of Open Access Journals (Sweden)

    Itamar Ferreira de Souza

    1985-12-01

    Full Text Available Três experimentos de campo foram conduzidos em Latossolos Vermelho-Escuro e Vermelho-Amarelo, nos anos 1981/82 e 1982/83 com o objetivo de determinar o efeito de herbicidas para o controle de plantas daninhas angustifoliadas e fitotoxidade sobre a cultura de soja, cultivares UFV-1 e Cristalina. O grupo das acetanilidas e pendimethalin controlaram a trapoeraba. Para as três espécies latifoliadas, o acetochlor, trifluralin e oryzalin foram eficientes. Além disso, o metolachlor controlou a poaia e o pendimethalin controlou a poaia e o apaga-fogo. Para o controle do capim-marmelada, todos os produtos foram eficientes, exceto quizalofop-etil e mefluidide, enquanto que para o capim-colchão apenas o mefluidide não foi eficiente. Finalmente, o timbete não foi eficientemente controlado por alachlor, metolachlor, pentimethalin e mefluidide. Acetochlor e oryzalin afetaram negativamente o stand inicial. Além disso, o acetochlor reduziu altura da inserção da primeira vagem. O quizalofop-etil causou uma redução na produção de grãos.Three field experiments were carried out on Dark Red Latosol and Yellow Red Latosol in 1981/82 and 1982/83 to evaluate the efficiency of herbicides upon grassy and their phytotoxicity upon “UFV-1” and Cristalina soybeans cultivars. The acetoanilide group and pendimethalin showed good epiderwort control. For the three broadleaved weed species, acetochlor, trifluralin and oryzalin were efficient. More over, metolachlor controlled Brazil pusley and A. ficoidea. For alexandergrass control all herbicides tested were efficient but quizalofop-ethyl and mefluidide, whereas crabgrass was not controlled by mefluidide only. Acetochlor and oryzalin treatments decreases initial stand. Besides, acetochlor decreased height of insertion of first pod. Quizalofop-ethil reduced grain yield of soybeans.

  2. Weed Control in Soybean (Glycine max)

    International Nuclear Information System (INIS)

    Kipkemoi, P.L.

    2002-01-01

    Weed Compete for limited growth factors with crop plants. This result in loss of crop vigour and hence reduces crop yields. A study was conducted in 1997 and 2001 to evaluate the use of herbicides and hand hoeing for weed control in soybeans. Crop establishment was by hand planting. The herbicides were applied using CP3 Knap sack sprayer calibrated to deliver a spray volume of 150l/ha. Hand weeding treatment were done as appropriate. The trial layout was randomised complete block design with four replications in both years. The tested herbicides did not satisfactorily control the weeds present at the experimental site in both years. Hand weeding on the other hand gave good control of the weeds which were reflected in high soybean yields. In these trials yields were negatively correlated with the number of weeds present. The tested herbicides alone appeared to be inadequate in controlling weeds in soybean. Compared with the weed-free treatment a single application of soil-applied or post-emergence herbicides did not control a broad spectrum of weeds and reduced soybean yields. It can also be inferred that soybean yield losses are minimised if they are kept weed free for at most 6 weeks after emergence

  3. Rounding Up the Astrophysical Weeds

    Science.gov (United States)

    McMillan, James P.

    2016-09-01

    New instruments used for astronomy such as ALMA, Herschel, and SOFIA have greatly increased the quality of available astrophysical data. These improved data contain spectral lines and features which are not accounted for in the quantum mechanical (QM) catalogs. A class of molecules has been identified as being particularly problematic, the so-called "weeds". These molecules have numerous transitions, of non-trivial intensity, which are difficult to model due to highly perturbed low lying vibrational states. The inability to properly describe the complete contribution of these weeds to the astrophysical data has led directly to the misidentification of other target molecules. Ohio State's Microwave Laboratory has developed an alternative approach to this problem. Rather than relying on complex QM calculations, we have developed a temperature dependent approach to laboratory based terahertz spectroscopy. We have developed a set of simple packages, in addition to traditional line list catalogs, that enable astronomers to successfully remove the weed signals from their data. This dissertation will detail my laboratory work and analysis of three keys weeds: methanol, methyl formate and methyl cyanide. Also, discussed will be the analytical technique I used to apply these laboratory results to astrophysical data.

  4. Variação da competição interespecífica em milho em função do controle de plantas daninhas em faixas Variation of interspecific weed competition in corn as a function of banded weed control

    Directory of Open Access Journals (Sweden)

    A. Merotto Jr.

    2001-08-01

    Full Text Available O controle de plantas daninhas em faixas é mais uma estratégia que pode ser utilizada no manejo integrado de plantas daninhas (MIPD para aumentar a racionalização do uso do ambiente no cultivo de plantas. Os objetivos deste trabalho foram determinar o efeito do controle de plantas daninhas em faixas na linha ou na entrelinha e avaliar suas conseqüências sobre a competição interespecífica na cultura do milho. Os tratamentos constaram do estabelecimento de um gradiente de infestação de Brachiaria plantaginea, obtido com a variação da intensidade do controle em pré-emergência, e do controle de plantas daninhas em pós-emergência realizado em faixas na linha, na entrelinha ou em área total. O controle de plantas daninhas em pós-emergência em faixas não foi suficiente para reduzir os efeitos da competição interespecífica sobre o rendimento de grãos de milho, mesmo em baixas densidades de plantas daninhas. Os prejuízos causados pela presença de plantas daninhas na linha da cultura são duas a três vezes maiores em comparação com a presença destas plantas na entrelinha ou em área total da cultura. O controle de plantas daninhas na linha da cultura necessita de complementação com práticas culturais ou outros métodos de controle destas plantas na entrelinha.Banded weed control is one of the methods used for integrated weed management (IWM to increase the rationalization of environmental use in crop activities management. The aim of this work was to determine the effect of in-and between-row weed control and the effects of weed competition on corn. The treatments consisted in the establishment of a range of Brachiaria plantaginea densities by varying the intensity of weed control in pre-emergence, complemented with post-emergence weed control in-row, between row and broadcast. Banded weed control was not efficient in decreasing weed competition and reducing corn grain yield, even at low weed infestation. In-row weed

  5. Overview of glyphosate-resistant weeds worldwide.

    Science.gov (United States)

    Heap, Ian; Duke, Stephen O

    2018-05-01

    Glyphosate is the most widely used and successful herbicide discovered to date, but its utility is now threatened by the occurrence of several glyphosate-resistant weed species. Glyphosate resistance first appeared in Lolium rigidum in an apple orchard in Australia in 1996, ironically the year that the first glyphosate-resistant crop (soybean) was introduced in the USA. Thirty-eight weed species have now evolved resistance to glyphosate, distributed across 37 countries and in 34 different crops and six non-crop situations. Although glyphosate-resistant weeds have been identified in orchards, vineyards, plantations, cereals, fallow and non-crop situations, it is the glyphosate-resistant weeds in glyphosate-resistant crop systems that dominate the area infested and growing economic impact. Glyphosate-resistant weeds present the greatest threat to sustained weed control in major agronomic crops because this herbicide is used to control weeds with resistance to herbicides with other sites of action, and no new herbicide sites of action have been introduced for over 30 years. Industry has responded by developing herbicide resistance traits in major crops that allow existing herbicides to be used in a new way. However, over reliance on these traits will result in multiple-resistance in weeds. Weed control in major crops is at a precarious point, where we must maintain the utility of the herbicides we have until we can transition to new weed management technologies. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  6. The future for weed control and technology.

    Science.gov (United States)

    Shaner, Dale L; Beckie, Hugh J

    2014-09-01

    This review is both a retrospective (what have we missed?) and prospective (where are we going?) examination of weed control and technology, particularly as it applies to herbicide-resistant weed management (RWM). Major obstacles to RWM are discussed, including lack of diversity in weed management, unwillingness of many weed researchers to conduct real integrated weed management research or growers to accept recommendations, influence or role of agrichemical marketing and governmental policy and lack of multidisciplinary research. We then look ahead to new technologies that are needed for future weed control in general and RWM in particular, in areas such as non-chemical and chemical weed management, novel herbicides, site-specific weed management, drones for monitoring large areas, wider application of 'omics' and simulation model development. Finally, we discuss implementation strategies for integrated weed management to achieve RWM, development of RWM for developing countries, a new classification of herbicides based on mode of metabolism to facilitate greater stewardship and greater global exchange of information to focus efforts on areas that maximize progress in weed control and RWM. There is little doubt that new or emerging technologies will provide novel tools for RMW in the future, but will they arrive in time? © 2013 Her Majesty the Queen in Right of Canada Pest Management Science © 2013 Society of Chemical Industry.

  7. WEED CONTROL EFFECTS ON SOIL CHEMICAL CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Paulo Sérgio Lima e Silva

    2008-01-01

    Full Text Available The weed control procedures are known to affect the soil physical attributes and the nutrient amount taken up by weed roots. This work hypothesis is that weed control methods might also affect soil chemical attributes. Four experiments were carried out, three with maize (E-1, E-2 and E-3 and one with cotton (E-4, in randomized complete blocks design arranged in split-plots, with five replications. In E-1 experiment, the plots consisted of two weed control treatments: no-weed control and weed shovel-digging at 20 and 40 days after sowing; and the subplots consisted of six maize cultivars. In the three other experiments, the plots consisted of plant cultivars: four maize cultivars (E-2 and E-3 and four cotton cultivars (E-4. And, the subplots consisted of three weed control treatments: (1 no-weed control; (2 weed shovel-digging at 20 and 40 days after sowing; and (3 intercropping with cowpea (E-2 or Gliricidia sepium (Jacq. Walp. (E-3 and E-4. In all experiments, after harvest, eight soil samples were collected from each subplot (0-20 cm depth and composed in one sample. Soil chemical analysis results indicated that the weed control by shovel-digging or intercropping may increase or decrease some soil element concentrations and the alterations depend on the element and experiment considered. In E-2, the weed shovel-dug plots showed intermediate soil pH, lower S (sum of bases values and higher soil P concentrations than the other plots. In E-4, soil K and Na concentrations in plots without weed control did not differ from plots with intercropping, and in both, K and Na values were higher than in weed shovel-dug plots. Maize and cotton cultivars did not affect soil chemical characteristics.

  8. DETERMINATION OF THE TOXIC EFFECTS OF MERCURY IN THE Brachiaria dictyoneura (Fig. & De Not. Stapf SPECIES

    Directory of Open Access Journals (Sweden)

    Gladis E. Morales

    2013-03-01

    Full Text Available In this research has been evaluated, on a laboratory scale, the toxic effect of mercury on the root development and biomass growth of the Brachiaria dictyoneura species, with the goal of finding an adequate concentration interval for the study on the accumulation of Hg (II. Brachiaria dictyoneura seeds were exposed to different amounts of mercury, the germination kinetics were determined, and after a 20 day growth period the length of the roots and the biomass were measured. There were found harmful effects on the root development starting at 25 mg*kg-1 Hg (II; for the dry biomass the differences were found starting at 5 mg*kg-1 Hg (II and starting at 75 mg*kg-1 Hg (II for the seed emergency time, therefore, working with concentrations not exceeding 25 mg Hg(II*kg-1 of substrate is suggested.

  9. Efectos del antecedente cultural en las micorrizas nativas y la productividad del pasto brachiaria (Brachiaria decumbens cv. Señal Effects of the cultural antecedent on native mycorhizae and the productivity of the brachiaria pasture (Brachiaria decumbens cv. Señal

    Directory of Open Access Journals (Sweden)

    P.J Gonzále

    2007-03-01

    Full Text Available Se evaluó la influencia del antecedente cultural en la micorrización nativa y en el rendimiento del pasto brachiaria (Brachiaria decumbens cv. Señal; para ello se seleccionaron dos lotes de 0,5 ha, los cuales durante cinco años previos a la siembra del pasto estuvieron ocupados, en un caso por cultivos de ciclo corto (granos, viandas y hortalizas y en otro por pastos naturales permanentes (principalmente especies del complejo Bothriochloa-Dichanthium y Teramnus labialis. En cada lote se delimitaron diez parcelas de 200 m² cada una, y en mayo de 2004 se sembró la brachiaria en surcos separados a 70 cm y a chorrillo, con una dosis de 8 kg de semilla total ha-1. Después del establecimiento el pasto se cortó cada seis y ocho semanas en los períodos lluvioso y poco lluvioso, respectivamente, y en ningún momento se aplicaron fertilizantes químicos u orgánicos. En cada parcela se tomaron muestras de raíces y de suelo de la rizosfera, para determinar las estructuras micorrízicas del pasto (porcentaje de colonización, porcentaje de densidad visual y número de esporas por 100 g, así como muestras de la biomasa aérea para determinar el contenido y la extracción de macronutrientes, y el rendimiento de MS. Las parcelas que tuvieron los pastos naturales como cultivo precedente mostraron valores significativamente mayores (PThe influence of the cultural antecedent on native mycorhization and the yield of the brachiaria pasture (Brachiaria decumbens cv. Señal was evaluated; for that two 0,5 ha lots were selected, which were occupied for five years before sowing the pasture, in one case by short cycle crops (grains, tubers and vegetables and in the other by permanent natural pastures (mainly species of the Bothriochloa-Dichanthium complex and Teramnus labialis. In each lot ten plots of 200 m² each were delimited, and in May, 2004, the brachiaria was sown in rows separated by 70 cm and with drilling, with a dose of 8 kg total seed ha-1. After

  10. Correspondence analysis evaluation of linear nutrient distribution in root tips of the tropical forage Brachiaria brizantha

    International Nuclear Information System (INIS)

    Pineda-Vargas, C.A.; Prozesky, V.M.; Przybylowicz, W.J.; Mayer, J.E.

    2001-01-01

    The technique of correspondence analysis was applied to a set of data obtained from X-ray elemental analysis by nuclear microscopy. Hydroponic experiments simulating tropical acid soil conditions were carried out to determine possible mechanisms of Al-toxicity stress on specific varieties of the genus Brachiaria. In particular the species Brachiaria brizantha was tested for gradient variation along the central cylinder of selected root tips. Single-point irradiations by nuclear microscopy gave some indication of a possible trace element profile gradient along the root axis. To be able to extrapolate the possible correlation and trace elemental concentrations gradients to a more confident level, this nuclear microscopy data obtained was analysed by correspondence analysis. A clear gradient on the plot of the first two axes of the correspondence analysis was found. The correlation of Ca and Cu as well as that of K and Cl were established

  11. Silicon as an attenuator of salt stress in Brachiaria brizantha ‘MG5’

    Directory of Open Access Journals (Sweden)

    Maria Isabel Leite da Silva

    Full Text Available ABSTRACT The aim of this study was to evaluate the effect of salt stress and silicon fertiliser on growth and nutritional value in Brachiaria brizantha ‘MG5’. The experimental design was completely randomised in a 4 x 5 x 3 factorial scheme with four replications; the treatments consisted of four concentrations of sodium chloride (0, 20, 40 and 60 mmol L-1, with five concentrations of silicon (0, 1, 2, 3 and 4 mmol L-1 in the nutrient solution, and three cutting periods (30, 60 and 90 days. The concentration of 4 mmol L-1 silicon minimised the detrimental effects of the sodium chloride on regrowth. However, the levels of silicon application were not sufficient to reduce the harmful effects of the sodium chloride on nutritional value or on dry-matter production in Brachiaria brizantha ‘MG5’.

  12. Avaliação da Brachiaria brizantha cv. marandu em sistemas silvipastoris Evaluation of Brachiaria brizantha cv. marandu in silvopastoral systems

    Directory of Open Access Journals (Sweden)

    G.R. Moreira

    2009-06-01

    Full Text Available Avaliou-se a degradabilidade in situ da matéria seca (MS da Brachiaria brizantha cv. marandu colhida em dois sistemas silvipastoris compostos pelas arbóreas, ipê felpudo (Zeyheria tuberculosa e aroeira (Myracrodruon urundeuva, localizados no bioma Cerrado, município de Lagoa Santa, MG. O período de coleta da forragem foi de dezembro de 2004 a abril de 2005. O delineamento utilizado foi em blocos ao acaso, segundo esquema de parcelas subdivididas, sendo as parcelas os tratamentos e as sub-parcelas os tempos de degradação. O sombreamento com as arbóreas não influenciou a degradabilidade in situ da matéria seca da forrageira.In situ degradability of dry matter of Brachiaria brizantha cv. marandu harvested in two silvopastoral systems was evaluated. One system was composed by Zeyheria tuberculosa tree and the other by Myracrodruon urundeuva, both located at Brazilian Savannah, Lagoa Santa, MG. A completely ramdomized block experimental design in a splitplot arrangement was used. The treatments were allocated in the plots and the times in the splitplot. No effect of shade was observed for in situ dry matter degradability.

  13. Precise tillage systems for enhanced non-chemical weed management

    NARCIS (Netherlands)

    Kurstjens, D.A.G.

    2007-01-01

    Soil and residue manipulation can assist weed management by killing weeds mechanically, interfering in weed lifecycles, facilitating operations and enhancing crop establishment and growth. Current tillage systems often compromise these functions, resulting in heavy reliance on herbicides,

  14. About the value of species diversity in arable weeds for weed management

    Directory of Open Access Journals (Sweden)

    Gerowitt, Bärbel

    2016-02-01

    Full Text Available Arable weeds accompany arable land use – we define them based on their affiliation to ar able systems. They are adapted to such a degree that most of them cannot exist without arable land use. Weeds are part of the total biodiversity on arable fields, as primary producers they are basic for important functions within the ecosystem. This paper elaborates the relevance of species diversity in arable weeds for their management. Arable systems can be regarded for the number of different methods for preventive and direct weed control which are realized. Historical arable land use is roughly divided into three periods, which differ concerning the diversity of weed management and the occurring diversity in weed species. Obviously divers weed management in arable systems and diversity in weed species depend on each other, this is illustrated with a simple abstract picture. Arable systems, which are characterised by simpleness, favor the domination of few species which ensure an effective use of the resources within the ecosystem. One consequence under continuous pressure of an overused tool in weed management is that the genetic diversity within a dominating weed population is exploited to ensure this resource use. Current herbicides represent this tool – the results are herbicide resistant biotypes within the weed populations. Species diversity in arable weeds as a rationale within arable production can assist to prevent this development.

  15. Combining a weed traits database with a population dynamics model predicts shifts in weed communities

    DEFF Research Database (Denmark)

    Storkey, Jonathan; Holst, Niels; Bøjer, Ole Mission

    2015-01-01

    A functional approach to predicting shifts in weed floras in response to management or environmental change requires the combination of data on weed traits with analytical frameworks that capture the filtering effect of selection pressures on traits. A weed traits database (WTDB) was designed, po...

  16. Effect of Weed Management on Weeds and Grain Yield of Haricot ...

    African Journals Online (AJOL)

    Weeds are one of the major constraints limiting haricot bean productivity and production. Field experiments were conducted on the effect of weed managements on weeds and grain yield of haricot bean (Phaseolus Vulgaris L.) at Melkassa Agricultural Research Center from 2011 - 2013. The objective was to determine the ...

  17. Weeds of onion fields and effects of some herbicides on weeds in ...

    African Journals Online (AJOL)

    Weeds are one of the most important problems in onion (Allium cepa L.) production areas, since onion plants are poor competitors. This study was conducted in order to identify the weed species in onion fields in Cukurova Region, establish the effects of some herbicides on weeds and the yield of onion in reducing the ...

  18. Effect of weed management on weeds and grain yield of haricot bean

    African Journals Online (AJOL)

    Weeds are one of the major constraints limiting haricot bean productivity and production. Field experiments were conducted on the effect of weed managements on weeds and grain yield of haricot bean (Phaseolus Vulgaris L.) at Melkassa Agricultural Research Center from 2011 - 2013. The objective was to determine the ...

  19. Linking Farmer Weed Management Behavior with Weed Pressure: More than Just Technology

    NARCIS (Netherlands)

    Riemens, M.M.; Groeneveld, R.M.W.; Kropff, M.J.; Lotz, L.A.P.; Renes, R.J.; Sukkel, W.; Weide, van der R.Y.

    2010-01-01

    Most studies on weed population dynamics in farming systems have focused on the effects of different weed control strategies. Those studies usually assume that farmers, operating within a particular system, have a uniform management style. However, it is likely that weed management decision making

  20. 1-14 Effect of Plant Spacing and Weeding Frequency on Weed ...

    African Journals Online (AJOL)

    user

    2College of Agriculture and Environmental Sciences, Haramaya University, ... pod, hundred seed weight, grain yield, aboveground dry biomass, and ... an infestation by weeds and the performance of crop ... frequencies affect weed management in common bean .... including broad-leaved, sedge and grass weeds (Table.

  1. Effect of stale seedbed preparations and subsequent weed control in lettuce (cv. Iceboll) on weed densities

    NARCIS (Netherlands)

    Riemens, M.M.; Weide, van der R.Y.; Bleeker, P.O.; Lotz, L.A.P.

    2007-01-01

    The effects of stale seedbed preparations and several weed control methods on the emergence of weeds in lettuce were studied. The specific goal was to evaluate the use of a stale seedbed in combination with chemical or mechanical weed control methods in the field. Depending on location and year,

  2. Different supplents for finishing of Nellore cattle on deferred Brachiaria decumbens pasture during the dry season

    Directory of Open Access Journals (Sweden)

    Antonio Tadeu de Andrade

    2015-07-01

    Full Text Available This study evaluated the effect of four types of supplement on the finishing of Nellore cattle on deferred Brachiaria decumbens pasture during the dry season. Sixty-four castrated Nellore males with an age of approximately 34 months and initial body weight (BW ranging from 360 to 380 kg were divided into 16 animals per treatment in a completely randomized design. The treatments consisted of four types of pasture supplement: deferred Brachiaria decumbens pasture + energy protein mineral salt (SuEPM used as control; deferred Brachiaria decumbens pasture + urea + cottonseed meal (28% CP + ground corn grain (SuCo; deferred Brachiaria decumbens pasture + urea + cottonseed meal (28% CP + citrus pulp (SuCPu; deferred Brachiaria decumbens pasture + urea + cottonseed meal (28% CP + soy hull (SuSH. The pasture was deferred for 170 days and provided 3,482 kg DM/ha of forage, permitting a stocking rate of 1.56 AU/ha (DM intake of 2.25% BW and 50% pasture efficiency. The animals received the supplement ad libitum in the SuEPM treatment and as % BW in the other treatments from July to October. The animals were slaughtered at a minimum BW of 457 kg. The following variables were evaluated: final weight, weight gain during the period (WG, average daily gain (ADG, hot carcass weight (HCW, and hot carcass yield (HCY. With respect to final weight, the supplement in the SuCo, SuCPu and SuSH treatments permitted a greater supply of nutrients and the animals therefore exhibited better performance (P<0.05 compared to the SuEPM treatment (mean of 478.68 vs 412.62 kg. The same effect was observed for the other parameters studied. Analysis of WG and ADG showed that SuSH was superior to the SuCo and SuCPu treatments (P<0.05 due to the increased offer of concentrate and SuEPM was inferior to the other treatments. Higher HCW (260.05 kg and HCY (53.92% were obtained with treatment SuSH as a result of greater performance. Supplementation of cattle during the dry period on

  3. A STUDY ON WEED CONTROL IN SOYBEAN

    Directory of Open Access Journals (Sweden)

    S. TJITROSEMITO

    1991-01-01

    Full Text Available Two field experiments on weed control in soybeans were carried out at BIOTROP, Bogor, Indonesia from February to June, 1989. The critical period for weed control was found to be between 20 - 40 days after planting of soybean (c. v. Wilis grown at a planting distance of 40 x 10 cm. It did not coincide with the fastest growth in terms of trifoliate leaf number. Further studies were suggested to understand the physiological growth of soybean related to weed control. Pendimethalin at 660- 1320 g a.e./ha applied one day after sowing did not cause any phytotoxic effect to soybean and had good weed control performance.

  4. Intoxicação por Brachiaria spp. em bovinos no Mato Grosso do Sul Brachiaria spp. poisoning in cattle in Mato Grosso do Sul, Brazil

    Directory of Open Access Journals (Sweden)

    Roosevelt I.C. Souza

    2010-12-01

    Full Text Available Mediante a revisão dos arquivos das fichas de necropsia do Laboratório de Patologia Animal, Universidade Federal do Mato Grosso do Sul, foram estudados a epidemiologia, o quadro clínico e a patologia de 29 surtos de intoxicação por Brachiaria spp., ocorridos em bovinos de corte, no Mato Grosso do Sul, de março de 1996 a novembro de 2009. Os surtos ocorreram em todas as épocas do ano, tanto na seca quanto na chuva. Em 24 dos 29 surtos o principal sinal clínico foi a fotossensibilização e em cinco o principal sinal foi o emagrecimento progressivo. Dos 24 surtos de fotossensibilização, 11 ocorreram em pastagens de B. decumbens, dois em pastagens mistas de B. decumbens e B. brizantha, um em B. brizantha e em 10 surtos não foi informada a espécie de Brachiaria envolvida. A morbidade variou de 0,2% a 50% e a letalidade de 44,4% a 100%. Nos casos de fotossensibilização o edema de barbela foi o sinal clínico mais encontrado em bovinos, seguido de dermatite com pele espessada no flanco e períneo, retração cicatricial auricular, icterícia, corrimento ocular. crostas auriculares e oculares, e ulcerações na parte ventral da língua. Em dois surtos foram observados sinais nervosos e em um, diarréia. Nas necropsias o fígado estava aumentado de tamanho, amarelado, com padrão lobular aumentado e, ocasionalmente, com áreas esbranquiçadas e deprimidas. Os rins estavam acastanhados e a urina escura. No exame histológico do fígado encontrou-se tumefação e vacuolização de hepatócitos, proliferação de células epiteliais dos ductos biliares, retenção biliar, fibroplasia periportal discreta ou moderada e infiltrado mononuclear periportal. Todos os casos de fotossensibilização apresentaram macrófagos espumosos no parênquima hepático e em 21 foram observados cristais birrefringentes nos ductos biliares. Cinco surtos com emagrecimento progressivo dos bovinos afetados foram diagnosticados em pastagens de B. decumbens. A

  5. The effect of sowing strategy, row distance and mechanical weed control on weeds and yield in organic winter wheat

    OpenAIRE

    Rasmussen, Ilse A.

    2002-01-01

    A series of field experiments were carried out in winter wheat grown under organic conditions in Denmark on fields with different weed pressure. The treatments were sowing strategy (normal sowing time, late sowing and false seedbed), row distance (12 cm and 24 cm row distance) and weed control method (untreated, mechanical weed control (weed harrowing at 12 cm supplemented with row hoeing at 24 cm), and herbicide weed control). Weed biomass was largest at the normal sowing time and was reduce...

  6. Ecological weed management by cover cropping : effects on weed growth in autumn and weed establishment in spring

    NARCIS (Netherlands)

    Kruidhof, H.M.; Bastiaans, L.; Kropff, M.J.

    2008-01-01

    Cover crops grown in the period between two main crops have potential as an important component of a system-oriented ecological weed management strategy. In late summer and autumn, the cover crop can suppress growth and seed production of weeds, whereas the incorporation of cover crop residues in

  7. Weeds in a Changing Climate: Vulnerabilities, Consequences, and Implications for Future Weed Management.

    Science.gov (United States)

    Ramesh, Kulasekaran; Matloob, Amar; Aslam, Farhena; Florentine, Singarayer K; Chauhan, Bhagirath S

    2017-01-01

    Whilst it is agreed that climate change will impact on the long-term interactions between crops and weeds, the results of this impact are far from clear. We suggest that a thorough understanding of weed dominance and weed interactions, depending on crop and weed ecosystems and crop sequences in the ecosystem, will be the key determining factor for successful weed management. Indeed, we claim that recent changes observed throughout the world within the weed spectrum in different cropping systems which were ostensibly related to climate change, warrant a deeper examination of weed vulnerabilities before a full understanding is reached. For example, the uncontrolled establishment of weeds in crops leads to a mixed population, in terms of C 3 and C 4 pathways, and this poses a considerable level of complexity for weed management. There is a need to include all possible combinations of crops and weeds while studying the impact of climate change on crop-weed competitive interactions, since, from a weed management perspective, C 4 weeds would flourish in the increased temperature scenario and pose serious yield penalties. This is particularly alarming as a majority of the most competitive weeds are C 4 plants. Although CO 2 is considered as a main contributing factor for climate change, a few Australian studies have also predicted differing responses of weed species due to shifts in rainfall patterns. Reduced water availability, due to recurrent and unforeseen droughts, would alter the competitive balance between crops and some weed species, intensifying the crop-weed competition pressure. Although it is recognized that the weed pressure associated with climate change is a significant threat to crop production, either through increased temperatures, rainfall shift, and elevated CO 2 levels, the current knowledge of this effect is very sparse. A few models that have attempted to predict these interactions are discussed in this paper, since these models could play an

  8. Bioherbicides: Current knowledge on weed control mechanism.

    Science.gov (United States)

    Radhakrishnan, Ramalingam; Alqarawi, Abdulaziz A; Abd Allah, Elsayed Fathi

    2018-04-17

    Weed control is a challenging event during crop cultivation. Integrated management, including the application of bioherbicides, is an emerging method for weed control in sustainable agriculture. Plant extracts, allelochemicals and some microbes are utilized as bioherbicides to control weed populations. Bioherbicides based on plants and microbes inhibit the germination and growth of weeds; however,few studies conducted in weed physiology. This review ascribes the current knowledge of the physiological changes in weeds that occur during the exposure to bioherbicides. Plant extracts or metabolites are absorbed by weed seeds, which initiates damage to the cell membrane, DNA, mitosis, amylase activity and other biochemical processes and delays or inhibits seed germination. The growth of weeds is also retarded due to low rates of root-cell division, nutrient uptake, photosynthetic pigment synthesis, and plant growth hormone synthesis, while the productions of reactive oxygen species (ROS) and stress-mediated hormones increase, including irregular antioxidant activity. However, lytic enzymes and toxic substances secreted from microbes degrade the weed seed coat and utilize the endosperm for survival, which inhibits seed germination. The microbes grow through the intercellular spaces to reach the root core, and the deposition of toxins in the cells affects cell division and cellular functions. Some of the metabolites of deleterious microbes cause disease, necrosis and chlorosis,which inhibit the germination and growth of weed seeds by suppressing photosynthesis and gibberellin activities and enhancing ROS, abscisic acid and ethylene. This review explains the effects of bioherbicides (derived from plants and microbes) on weed-plant physiology to elucidate their modes of action. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Sistemas de produção de grãos e incidência de plantas daninhas Weed incidence in grain production systems

    Directory of Open Access Journals (Sweden)

    G.S.A Castro

    2011-01-01

    /soybean; and IV "Harvest-fodder" System-brachiaria + soy/corn + brachiaria/brachiaria + rice/ soybeans.A weed survey was carried out in November 2009, after three growing seasons. A 0.3 x 0.3 m frame was randomly launched four times within each plot. The plants were identified, and the total number of weeds, dry weight, and control percentage of the species were determined according to the production system. The phytosociological analysis of the weed community was also conducted. The systems Harvest-green manure; Harvest-out of season and Harvest-fodder presented a good weed control when compared to the Harvest-fallow system. Therefore, the presence of some type of soil cover is important to maintain favorable soil characteristics and good weed control.

  10. DIGESTIBILIDADE APARENTE DO FENO DE Brachiaria humidicola (Rendle SCHWEICKERDT APÓS A COLHEITA DE SEMENTES APPARENT DIGESTIBILITY OF Brachiaria humidicola (RENDLE SCHWEICKERDT HAY AFTER SEED HARVEST

    Directory of Open Access Journals (Sweden)

    Benir de Oliveira

    2007-09-01

    Full Text Available

    Objetivando avaliar a composição química e a digestibilidade aparente de feno de Brachiaria humidicola (Rendle Schweickerdt, após a colheita de sementes, foi realizado um experimento nas dependências do Departamento de Zootecnia da Escola de Veterinária da Universidade Federal de Goiás. Utilizou-se quatro carneiros adultos, castrados, sem raça definida, com bolsas coletoras de fezes e alojados em gaiolas individuais de metabolismo durante 17 dias, sendo 7 de adaptação e 10 de coleta. A digestibilidade aparente da matéria seca (53,64% concorda plenamente com o resultado encontrado "in vitro" (53,37%. Na base de matéria seca, o feno apresentou 53,40% de N.D.T., baixo nível de proteína bruta (3,03% com baixo coeficiente de digestibilidade (11,88%. Nas condições do presente experimento conclui-se que a fenação da Brachiaria humidicola, após a colheita mecânica das sementes, prejudicou o valor nutritivo do feno, principalmente, a proteína bruta e sua digestibilidade.

    A trial to study the apparent digestibility of Brachiaria humidicola (Rendle Schweickerdt, grass, was carried out at the Departamento de Zootecnia da Universidade Federal de Goiás. The seeds of B.humidicola have a good commercial value and the farmers utilized a grass of bad quality after mechanical harvest. Four adult lambs, castrated males, of unknown race, were used and placed in metabolical individual cages during 17 days, 7 for adaptation and 10 for collection period. The apparent digestibility of dry matter was 53.64% and ";in vitro"; 53.37%. On dry matter-basis the hay has 53.40% of TND value, a poor crude protein (3.03% value with low coefficient of digestibility (11 .88%.

  11. Estrutura do capim-braquiária em relação à planta daninha = Structure of signalgrass in relation to weeds

    Directory of Open Access Journals (Sweden)

    Manoel Eduardo Rozalino Santos

    2011-07-01

    Full Text Available O objetivo foi avaliar as características estruturais da Brachiaria decumbens cv. Basilisk em relação à planta daninha Solanum sisymbrifolium no pasto. Os tratamentos foram dois locais no mesmo pasto, quais sejam, próximo e distante da planta daninha. O delineamento foi em blocos ao acaso com três repetições. O pasto foi manejado sob lotação contínua, com bovinos e com altura média de aproximadamente 25 cm. Foram quantificadas as densidades populacionais das categorias de tamanho dos perfilhos, a altura, a interceptação de luz, as massas e as densidades volumétricas dos componentes morfológicos do pasto. No local distante da planta daninha houve maior ocorrência de perfilhos com tamanho inferior a 20 cm. Já no local próximo da planta daninha, predominaram perfilhos com tamanho superior a 40 cm. A presença da planta daninha ocasionou aumento na altura do pasto e incremento na interceptação de luz pelo dossel. As massas e as densidades volumétricas de lâmina foliar viva, colmo vivo e material morto foram inferiores no local próximo da planta daninha em relação ao local distante. A ocorrência da planta S. sisymbrifolium provoca variabilidade espacial da vegetação no pasto de B. decumbens manejado sob lotação contínua com bovinos.The objective of this study was to evaluate the structural characteristics of Brachiaria decumbens cv. Basilisk in relation toSolanum sisymbrifolium in pasture. The treatments were two sites in the same pasture, near and far from the weeds. A randomized block design with three replications was used. The pasture was managed under continuous stocking and grass height was kept at about 25cm.Densities were quantified for categories tiller size, height, light interception, masses and volumetric densities of morphological components of the pasture. In the site far from the weeds there is a higher occurrence of tillers with size smaller than 20 cm. In site near the weeds, tillers larger than 40 cm

  12. Azafenidin: novo herbicida para o controle de plantas daninhas em Eucalyptus camaldulensis Azafenidin: a new herbicide for weed control in Eucalyptus camaldulensis

    Directory of Open Access Journals (Sweden)

    J. Constantin

    2000-01-01

    Full Text Available Um experimento de campo foi conduzido em Presidente Castelo Branco-PR, com o objetivo de avaliar a seletividade do herbicida azafenidin para a cultura de Eucalyptus camaldulensis, assim como sua eficácia no controle de algumas plantas daninhas infestantes nessa cultura. Azafenidin foi aplicado nas doses de 300, 400, 500 600 e 800 g i.a. ha-1, em pré-emergencia das plantas daninhas. Tratamentos adicionais, incluindo oxyfluorfen (720 g i.a. ha-1, uma testemunha capinada e outra testemunha sem capina, foram também incluídos. Tanto azafenidin quanto oxyfluorfen provocaram sintomas de toxicidade na cultura; no primeiro, as injúrias foram mais intensas em doses ³ 600 g i.a. ha-1. Em relação ao controle de plantas daninhas, doses de azafenidin a partir de 500 g i.a. ha-1 foram efetivas no controle de Brachiaria decumbens, Commelina benghalensis, Richardia brasiliensis e Sida santaremnensis, mesmo 180 dias após a aplicação. Doses menores de azafenidin resultaram em controle suficiente da maioria das plantas daninhas, mas com menor efeito residual.A field experiment was conducted at Presidente Castelo Branco, PR, Brazil, to evaluate the selectivity of the herbicide azafenidin to the crop Eucalyptus camaldulensis, as well as its efficacy to control some infesting weeds in this crop. Azafenidin was applied under pre-emergence conditions, at rates of 300, 400, 500, 600 and 800 g a.i. ha-1. Additional treatments, including oxyfluorfen (720 g a.i. ha-1, a weed free and a weeded check plots were also included. Both azafenidin and oxyflluorfen caused crop symptoms of phytotoxicity, with injuries being more intense for azafenidin at rates ³ 600 g a.i. ha-1. For weed control, rates of azafenidin at 500 g a.i. ha-1 or higher were effective in controlling Brachiaria decumbens, Commelina benghalensis, Richardia brasiliensis and Sida santaremnensis, even at 180 days after application. Lower rates of azafenidin provided enough control of most weeds, but

  13. WEED SURVEYING OF PHACELIA (PHACELIA TANACETIFOLIA L.) AND EVALUATING THE EFFICIENCY OF THE WEED CONTROL.

    Science.gov (United States)

    Horváth, E; Szabó, R

    2014-01-01

    The experiment was set up in an area of 9 ha that was split into 4 plots: in plot 1 the row spacing was 12 cm and the seeding rate was 10 kg; in plot 2 the row spacing was 24 cm and the seeding rate was 10 kg; in plot 3 the row spacing was 24 cm and the seeding rate was 8 kg; in plot 4 the row spacing was 12 cm and the seeding rate was 8 kg. After the weed surveying, the total weed coverage was established as follows: in plot 1 the total weed coverage was 11.34%, in plot 2 it was 12.3%, in plot 3 it was 18%, and in plot 4 the total weed coverage was 15%. Based on the weed survey, on the test area the following dicotyledon weeds belonging to the T4 Raunkiaer plant life-form category occupied the highest percentage: heal-all, black-bindweed, goosefoot. The proportion of the perennial dicotyledons: field bindweed (G3), tuberous pea (G1), white campion (H3) was negligible. In all four cases the weed control was executed using the same herbicide in the same doses and with regard to the weed species it showed the same level of efficiency. The smaller row spacing and higher seeding rate has a beneficial effect on the weed suppressing capacity of the crop, the crop's weed suppressing capacity is better and the development of the weeds becomes worse.

  14. An autonomous weeding robot for organic farming

    NARCIS (Netherlands)

    Bakker, T.; Asselt, van C.J.; Bontsema, J.; Müller, J.; Straten, van G.

    2006-01-01

    The objective of this research is the replacement of hand weeding in organic farming by a device working autonomously at ¯eld level. The autonomous weeding robot was designed using a structured design approach, giving a good overview of the total design. A vehicle was developed with a diesel engine,

  15. Weeds as important vegetables for farmers

    NARCIS (Netherlands)

    Cruz Garcia, G.S.; Price, L.L.

    2012-01-01

    The objective of this study was to investigate the multiple uses and cognitive importance of edible weeds in Northeast Thailand. Research methods included focus group discussions and freelistings. A total of 43 weeds consumed as vegetable were reported, including economic, naturalized, agricultural

  16. Weed management strategies for castor bean crops

    Directory of Open Access Journals (Sweden)

    Augusto Guerreiro Fontoura Costa

    2014-04-01

    Full Text Available Castor bean crops are agriculturally relevant due to the quality and versatility of their oil, both for the chemical industry and for biodiesel production. Proper weed management is important for both the cultivation and the yield of castor bean crops; therefore, the intention of the present work is to review pertinent information regarding weed management, including the studies regarding weed interference periods, chemical controls for use in different crop production systems and herbicide selectivity, for castor bean crops. Weed science research for castor bean crops is scarce. One of the main weed management challenges for castor bean crops is the absence of herbicides registered with the Ministry of Agriculture, Livestock and Food Supply (MALFS. Research for viable herbicides for weed control in castor bean crops should be directed by research and/or rural extension institutions, associations and farmers cooperatives, as well as by manufactures, for the registration of these selective herbicides, which would be primarily used to control eudicotyledons in castor bean crops. New studies involving the integration of weed control methods in castor bean also may increase the efficiency of weed management, for both small farmers using traditional crop methods in the Brazilian Northeast region, as well as for areas with the potential for large scale production, using conservation tillage systems, such as the no-tillage crop production system.

  17. Effectiveness of weed control methods on pavement

    NARCIS (Netherlands)

    Vermeulen, G.D.; Verwijs, B.R.; Kempenaar, C.

    2007-01-01

    The policy in the Netherlands is to signifiantly reduce the use of herbicides, also on pavements. Existing non-chemical methods to control weeds are much less effective than spot spraying, the usual method at this moment. Therefore, the cost of non-chemical weed management is often estimated to be 4

  18. Physiological and morphological responces of Brachiaria spp. to flooding Respostas morfológicas e fisiológicas de Brachiaria spp. ao alagamento do solo

    Directory of Open Access Journals (Sweden)

    MOACYR BERNARDINO DIAS-FILHO

    2000-10-01

    Full Text Available The physiological and morphological responses of the forage grasses Brachiaria brizantha cv. Marandu, B. decumbens and B. humidicola were compared for plants grown in pots under flooding and well-drained conditions for 14 days. Flooding reduced specific leaf area and biomass allocation to roots in all species and enhanced leaf senescence in B. brizantha and B. decumbens. Relative growth rate was reduced by flooding in B. brizantha and B. decumbens, but not in B. humidicola.Leaf elongation rate was unaffected by flooding in B. decumbens and B. humidicola, but declined in B. brizantha since the first day of flooding. Net photosynthesis and leaf chlorophyll content were reduced by flooding in B. brizantha; however, no flooding effect could be detected in the other two species. For all species, there was a close relationship between net photosynthesis and stomatal conductance under flooding. These results show that the studied species have distinct degrees of tolerance to flood, B. brizantha is intolerant, B. decumbens is moderately tolerant and B. humidicola is tolerant. Because leaf elongation rate was immediately depressed by flooding only in B. brizantha, this measurement could be appropriate as an early detection mechanism for relative flood tolerance in Brachiaria spp.As respostas morfológicas e fisiológicas de Brachiaria brizantha cv. Marandu, B. decumbens e B. humidicola foram comparadas em plantas cultivadas em vasos, sob solo alagado e bem drenado durante 14 dias. O alagamento reduziu a área foliar específica e a alocação de biomassa para as raízes em todas as três espécies e aumentou a senescência foliar em B. brizantha e B. decumbens. O alagamento reduziu a taxa de crescimento relativo em B. brizantha e B. decumbens, mas não em B. humidicola. A taxa de elongação foliar não foi afetada pelo alagamento em B. decumbens e B. humidicola, mas diminuiu em B. brizantha desde o primeiro dia de alagamento. A fotossíntese líquida e

  19. SULPHUR DEFICIENCY IN DAIRY CALVES REARED ON PASTURE OF Brachiaria decumbens DEFICIÊNCIA DE ENXOFRE EM BEZERROS LEITEIROS MANTIDOS EM PASTAGEM DE Brachiaria decumbens

    Directory of Open Access Journals (Sweden)

    Enrico Lippi Ortolani

    2001-04-01

    Full Text Available The clinical picture of sulphur (S deficiency is described by the first time in Brazilian dairy calves. Twelve crossbred six-month-old weaned dairy calves, reared on pasture of S-deficient Brachiaria decumbens, were used. The calves were randomly assigned in two groups of six calves each to verify the influence of S supplementation on some clinical and serum biochemical variables. All animals were fed a basal-supplement mix containing macro and microlements, urea and ground corn grain added (41gS/kg or not of S (elemental S; 1g S/kg, for six months. At the end of the experiment, the S-supplemented calves had higher mean body weight (p São descritos, pela primeira vez no Brasil, os sinais clínicos de bezerros leiteiros com deficiência de enxofre (S. Doze bezerros mestiços, recém-desmamados e com seis meses de idade, foram distribuídos, ao acaso, em dois grupos iguais. Todos os animais pastejaram em piquetes de Brachiaria decumbens e receberam, por seis meses, um suplemento básico contendo macro e microelementos, uréia e fubá, contendo 1gS/kg. No segundo grupo, essa mistura era suplementada com S-elementar para conter 41gS/kg. Ao término do experimento, o grupo suplementado com S apresentou um maior ganho de peso (p < 0,01, melhor condicão corporal (p < 0,016, e maiores concentrações séricas de sulfato inorgânico (p < 0,001 e de albumina ( p < 0,01 que os bezerros não suplementados. Os animais deficientes em S apresentaram perda de condição corporal, retardo de crescimento, perda de peso e discreta apatia.

  20. Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia Rooting strategies of Brachiaria genotypes in acid and low fertility soils of Colombia

    Directory of Open Access Journals (Sweden)

    Jaumer Ricaurte

    Full Text Available En un Haplustox de los Llanos Orientales de Colombia se evaluaron durante 41 meses 6 genotipos de Brachiaria con resistencia variable a niveles altos de Al+3 en dos niveles de nutrientes. Los genotipos con resistencia media y alta mantuvieron altas producciones de biomasa aérea en los primeros meses, decrecieron a valores medios y estables hacia los 21 meses. La producción de biomasa y longitud de raíces en los genotipos de Brachiaria y especies de sabana nativa fue mayor en época lluviosa, con alta producción en los primeros 5 cm del perfil de suelo. Las gramíneas de la sabana nativa y B. decumbens CIAT 606 (altamente resistente a Al+3 generaron raíces finas y menor biomasa de raíces. Durante la época seca los genotipos de Brachiaria con resistencia media y alta a aluminio generaron raíces más profundas que la sabana nativa. La época seca indujo una producción de longitud y biomasa de raíces proporcionalmente más profundas que la lluviosa, tanto en genotipos de Brachiaria con resistencia media y alta a aluminio como en especies de la sabana nativa.In a Typic Haplustox soil in the “Altillanura” of the Eastern Plains (Llanos Orientales of Colombia Shoot biomass production was evaluated, during 41 months in 6 Brachiaria genotypes with variable resistance to high Al levels. with two nutrient levels. Moderate and highly Al-resistant Brachiaria genotypes maintained high shoot biomass production in early months of establishment, declined to medium values until 21 months. Root biomass and root length production of Brachiaria genotypes, as well as native savanna grasses, was greater during rainy season, with a high root production in the first 5 cm of the soil. Savanna species and the genotypes B. decumbens CIAT 606 (high Al+3 resistant produced finer roots and less root biomass than native savanna species. The dry season induced a proportional increase in deeper root length and biomass production compared with rainy season in both

  1. Brachiaria spp. poisoning in cattle in Mato Grosso do Sul, Brazil

    OpenAIRE

    Souza, Roosevelt I.C.; Riet-Correa, Franklin; Brum, Karine B.; Fernandes, Carlos Eurico; Barbosa-Ferreira, Marcos; Lemos, Ricardo A. Amaral de

    2010-01-01

    Mediante a revisão dos arquivos das fichas de necropsia do Laboratório de Patologia Animal, Universidade Federal do Mato Grosso do Sul, foram estudados a epidemiologia, o quadro clínico e a patologia de 29 surtos de intoxicação por Brachiaria spp., ocorridos em bovinos de corte, no Mato Grosso do Sul, de março de 1996 a novembro de 2009. Os surtos ocorreram em todas as épocas do ano, tanto na seca quanto na chuva. Em 24 dos 29 surtos o principal sinal clínico foi a fotossensibilização e em ci...

  2. Effect of Cultural Practices in Night on Weed Density and Weed Dry Matter

    Directory of Open Access Journals (Sweden)

    M.H Rashed Mohasel

    2011-01-01

    Full Text Available Abstract In order to evaluate the response of weed seeds to light, two experiments, at two different locations were conducted at Ferdowsi university of Mashhad in 2009. At the first experiment, field was ploughed in day and night. Weed density was evaluated 70 d after plough, with 1×1 quadrate. At the second experiment, at night treatment, ploughing, potato planting and weeding with cultivator were done at night. Weed sampling was done twice at 43 and 130 days after planting with 1×1 quadrate and weeds were identified and counted. Result showed pigweed (Amaranthus retroflexus L., sowthistle (Sonchus oleraceus L., crabgrass (Digitaria sanguinalis (L. scop, jimsonweed (Datura stramonium L. and mallow (Hibiscus trionum L. did not observed at night plough, in contrast, night plough has no significance influence on common lambsquarters (Chenopodium album L., and black nightshade (Solanum nigrum L.. Only common lambsquarters had similar appearance in two treatments, indicating insusceptibility of this weed to time of plough. Interestingly, at the second experiment, result was very similar. Potato yield was higher at night treatment, but not significant. This research showed that some cultural practice like plough, planting and weeding with cultivator in night can reduce weed density and weed dry matter. Keywords: Germination, Time of plough, Sustainable weeds management, Light

  3. The changing role of agriculture and tomorrow's weed research agenda

    NARCIS (Netherlands)

    Kropff, M.J.; Bastiaans, L.; Kempenaar, C.; Weide, van der R.Y.

    2008-01-01

    With the changing position of agriculture in the world the challenges for weed management and weed science are changing as well. In this paper recent developments in weed science with respect to several aspects of weed management are discussed in relation to those changes. Developments in cultural

  4. Seeding method and rate influence on weed suppression in aerobic ...

    African Journals Online (AJOL)

    High weed pressure is amongst the major constraints to the extensive adoption of aerobic rice system as a water-wise technique. Towards developing a sustainable weed management strategy, seeding method and rate may substantially contribute to weed suppression and reduce herbicide use and weeding cost. A trough ...

  5. Influence of cowpea and melon populations on weed infestation and ...

    African Journals Online (AJOL)

    Small farmers in the humid regions of tropical Africa spend 30–42% of their total farm labour input in controlling weeds. Chemical weed control is normally recommended but high cost of herbicides and environmental pollution are specific problems with chemical weed control. A three year bio-weed control system with three ...

  6. Adapting weed management in rice to changing climates

    NARCIS (Netherlands)

    Rodenburg, J.; Meinke, H.B.

    2011-01-01

    This paper provides some of the scientific background on how projected environmental conditions could affect weeds and weed management in rice in Africa. Elevated CO2 levels may have positive effects on rice competitiveness with C4 weeds, but these are generally outnumbered by C3 species in weed

  7. Weed Garden: An Effective Tool for Extension Education

    Science.gov (United States)

    Beck, Leslie; Patton, Aaron J.

    2015-01-01

    A weed garden was constructed to quantify and improve identification skills among clientele. The garden was planted with over 100 weed species based on surveys on problematic weeds. The weed garden proved useful for introducing additional hands-on learning activities into traditional lecture-based seminars. Through seminar and field day attendee…

  8. Controle pós-emergente de plantas daninhas em cenoura Post-emergence weed control in carrot crop

    Directory of Open Access Journals (Sweden)

    Jeferson Zagonel

    1999-03-01

    Full Text Available O experimento foi conduzido em Piraí do Sul-PR no ano de 1995 em solo de textura argilo arenosa, tendo como objetivo avaliar a eficiência e a seletividade do herbicida propaquizafop no controle pós-emergente de plantas daninhas na cultura da cenoura. O delineamento experimental utilizado foi de blocos ao acaso com seis tratamentos e quatro repetições, quais sejam: propaquizafop (100, 125 e 150 g i.a./ha; fluazifop-p-butil (188 g i.a./ha; testemunha capinada e testemunha sem capina. A cultivar de cenoura utilizada foi Nantes Tim Tom semeada em 15 de junho, com espaçamento de 0,25 x 0,05 m, em parcelas com área útil de 5,00 x 1,00 m. As plantas daninhas predominantes foram Brachiaria plantaginea (capim-papuã, Digitaria horizontalis (capim-milhã e Eleusine indica (capim pé-de-galinha. As avaliações foram efetuadas aos 15, 30 e 45 dias após a aplicação dos tratamentos. Observou-se que o herbicida propaquizafop, nas doses de 100, 125 e 150 g i.a./ha foi eficiente no controle sobre capim-papuã, capim-milhã e capim pé-de-galinha. O controle de plantas daninhas realizado através de herbicidas proporcionou a mesma produção obtida com o controle manual. A perda na produção ocasionada pela presença de plantas daninhas foi da ordem de 76,4%. Não foram observados efeitos fitotóxicos nas plantas de cenoura que pudessem ser atribuídos aos produtos utilizados.The presented field trial was conducted in 1995 in Piraí do Sul, Paraná State, Brazil, on a sand-clay texture soil, to evaluate the efficiency and selectivity of propaquizafop on carrot crop weed control. The experiment was laid out in a randomized block design with six treatments and four replications, and 5.00 x 1.00 m plots. The treatmens were: propaquizafop (100, 125 and 150 g a.i/ha; fluazifop-p-butil (188 g a.i/ha; control with weeding and control without weeding. The carrot cultivar Nantes Tim Tom was sown on June 15 with plants spaced 0.25 x 0.05 m. The prevalent weeds

  9. Soil solarization for weed control in carrot

    Directory of Open Access Journals (Sweden)

    MARENCO RICARDO ANTONIO

    2000-01-01

    Full Text Available Soil solarization is a technique used for weed and plant disease control in regions with high levels of solar radiation. The effect of solarization (0, 3, 6, and 9 weeks upon weed populations, carrot (Daucus carota L. cv. Brasília yield and nematode infestation in carrot roots was studied in São Luís (2º35' S; 44º10' W, MA, Brazil, using transparent polyethylene films (100 and 150 mm of thickness. The maximum temperature at 5 cm of depth was about 10ºC warmer in solarized soil than in control plots. In the study 20 weed types were recorded. Solarization reduced weed biomass and density in about 50% of weed species, including Cyperus spp., Chamaecrista nictans var. paraguariensis (Chod & Hassl. Irwin & Barneby, Marsypianthes chamaedrys (Vahl O. Kuntze, Mitracarpus sp., Mollugo verticillata L., Sebastiania corniculata M. Arg., and Spigelia anthelmia L. Approximately 40% of species in the weed flora were not affected by soil mulching. Furthermore, seed germination of Commelina benghalensis L. was increased by soil solarization. Marketable yield of carrots was greater in solarized soil than in the unsolarized one. It was concluded that solarization for nine weeks increases carrot yield and is effective for controlling more than half of the weed species recorded. Mulching was not effective for controlling root-knot nematodes in carrot.

  10. LEVANTAMENTO DA FLORA EMERGENTE DE PLANTAS DANINHAS EM SISTEMAS DE COBERTURA DO SOLO SURVEY OF THE WEED EMERGING FLORA IN SOIL COVER SYSTEMS

    Directory of Open Access Journals (Sweden)

    Nicolas Bernon

    2007-09-01

    Full Text Available

    O objetivo deste trabalho foi determinar a flora emergente de plântulas e plantas daninhas em vários sistemas de cobertura do solo e manejo com: a culturas de cobertura em plantio direto (feijão-de-porco; braquiária; milheto; mucuna cinza; aveia; mucuna rajada; trigo sarraceno; crotalária e b sistemas de cultivo (cultivo mínimo; retirada da cobertura; plantio direto no mato; plantio convencional. A avaliação da flora emergente demonstrou que, dentre as culturas de cobertura, os tratamentos com milheto e braquiária apresentaram baixa incidência de monocotiledôneas (0,66 pl/m², diferenciando-se, entretanto, apenas do plantio convencional (50,33 pl/m². A ocorrência de dicotiledôneas foi inibida quando em presença de crotalária, trigo sarraceno e milheto (1,00; 1,00; 1,33 pl/m², respectivamente, que se diferenciaram dentre as culturas de cobertura, apenas da aveia (18,66 pl/m². Houve uma elevada população de plantas residuais de milheto (130,66 pl/m², estatisticamente superior ao residual das culturas de braquiária, mucuna cinza, mucuna rajada (1,00; 0,00; 0,33 pl/m², respectivamente. Concluiu-se que a cobertura total do solo foi a proporcionada pela braquiária, com eficiente controle de plantas daninhas. O milheto e a crotalária controlaram muito bem as espécies mono e dicotiledôneas, estabelecendo uma boa cobertura do solo. Contudo, a emergência de plântulas de milheto, após o cultivo desta cultura, pode dificultar o manejo para implantação da cultura subseqüente.

    PALAVRAS-CHAVE: Sistemas; plantas daninhas; manejo; flora.

    The emerging flora of seedlings and weeds in several soil cover systems was studied through: a cover crops under no-tillage (pigpeas; brachiaria; pearl millet; gray mucuna; oats; striped mucuna; saracen wheat; crotalaria and

  11. Biological weed control with soil fungi? Antagonistic effects of arbuscular mycorrhizal fungi on the growth of weeds

    NARCIS (Netherlands)

    Veiga, R.

    2012-01-01

    Excessive weed growth represents one of the major threats to crop production especially when reliance on herbicides is reduced. Biological weed control is an alternative, environmentally-sound method that, combined with other weed control practices, can contribute to an effective weed management in

  12. Weed suppression ability of spring barley varieties

    DEFF Research Database (Denmark)

    Christensen, Svend

    1995-01-01

    , Grit. Ranking varietal responses to weed competition in terms of grain yield loss corresponded well to ranking weed dry matter produced in crop weed mixtures. There was no correspondence between the varietal grain yields in pure stands and their competitiveness, suggesting that breeding to optimize...... both yielding and competitive ability may be possible. Non-linear regression models were fitted to canopy height and light interception data for each variety in all three years. The canopy height model provided a precise description of development and maximum canopy height of the varieties. A light...

  13. Assessing the potential of brachiaria decumbens as remediation agent for soil contaminated wit oil sludge

    International Nuclear Information System (INIS)

    Latiffah Norddin; Ahmad Nazrul Abd Wahid; Hazlina Abdullah; Abdul Razak Ruslan

    2005-01-01

    Bioremediation is a method of treatment of soil or water contaminated with toxic materials, involving the use of living organisms. Oil or petroleum sludge is a waste product of the petroleum refining industry, and is now accumulating at a fast rate at petroleum refinery sites in the country. Common components of oil sludge are mud and sand, containing toxic materials from hydrocarbons, heavy metals and radioactive elements from the seabed. In the present study, the oil sludge samples were obtained from barrels of the materials stored at the Radioactive Waste Treatment Centre, MINT. The samples were analysed of their compounds, elemental and radioactive contents. Trials on microbial degradation of the sludge materials were ongoing. This paper discusses the potential of a grass to remediate soils contaminated with petroleum sludge. Remediation of soils contaminated with organic compounds and heavy metals using plants, including grasses, including Vetiver, Lolium and Agrostis have been carried out in many countries. A greenhouse pot trial was conducted to assess the suitability of the pasture grass Brachiaria decumbens Stapf. and its mutant Brachiaria decumbens KLUANG Comel as a remediation agent for oil sludge contaminated soil. Samples of grasses and soils before planting, during growth stage and at end of experiment were analysed for the different toxicity. Although the grasses were promoted for use in pasture, and KLUANG Comel has good potential as an ornamental plant, too, their other potentials, including as phytoremediation agents need to be explored. (Author)

  14. Ecophysiological and anatomical changes due to uptake and accumulation of heavy metal in Brachiaria decumbens

    Directory of Open Access Journals (Sweden)

    Marcelo Pedrosa Gomes

    2011-10-01

    Full Text Available The growth and developmental characteristics of grasses and their high biodiversity make such plants suitable for remediation of areas contaminated by heavy metals. Nevertheless, heavy metal toxic effect on the plants may cause alteration in their metabolic pathways, such as photosynthesis, respiration, and growth, modifying plant anatomy. This work aimed to evaluate the effect of levels of soil contamination (0, 7.5 % and 15 % m³ m-3 on biomass production, on photosynthetic characteristics and on anatomical changes in roots and leaves of brachiaria (Brachiaria decumbens Stapf.. After seeds were planted, seedlings were uprooted and replanted in vases containing soil at different contamination levels, being left to rest for 120 days. At the end of that time, plants presented reduced yield of root and shoot dry matter, contents of chlorophyll a, chlorophyll b, total chlorophyll and potential photosynthesis with increased of soil contamination. The cell layers of endodermis and exodermis in the root tissues and the cell walls of the xylem and cortical parenchyma all thickened as contamination increased. In the leaf tissues, the adaxial and abaxial epidermis presented increased thickness while the leaf blade presented reduced thickness as contamination increased with consequent change in the root growth rate. In general, the effects of heavy metal increased with the metal concentration. Some results indicate that B. decumbens seems to have some degree of heavy metal tolerance.

  15. Liming and plant aging influence on micronutrient uptake by Brachiaria decumbens forage

    International Nuclear Information System (INIS)

    Armelin, Maria Jose A.; Saiki, Mitiko; Primavesi, Odo; Primavesi, Ana C.

    2007-01-01

    Brachiaria decumbens is the main forage in pastures of several Brazilian regions. The effects of liming and plant age on micronutrient uptake by the forage of a degraded Brachiaria decumbens pasture under restoration process, were studied in Sao Carlos - SP, southeastern Brazil, under altitude tropical climate. Experimental design was a random block (100 m 2 ), with 6 replications and 3 treatments. Each block received the following treatment: 0 t/ha of limestone with NK; 2 t/ha of limestone applied on soil surface with NK and maintenance of 1 t/ha per annum; 8 t/ha of limestone applied once on soil surface with NK. Forage samples were collected 14 cm above soil surface, each 36 days in the rain season. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine the micronutrient content. In some cases, Co Fe, Mn and Zn were negatively affected by increasing limestone doses. The opposite effect was observed for Cl. Decreases of Cl, Co and Mo uptake in forage were enhanced with plant aging. (author)

  16. The Damage Capacity of Mahanarva spectabilis (Distant, 1909 (Hemiptera: Cercopidae Adults on Brachiaria ruziziensis Pasture

    Directory of Open Access Journals (Sweden)

    Tiago Teixeira Resende

    2013-01-01

    Full Text Available The aim of this study was to determine the damage caused by adult Mahanarva spectabilis (Distant, 1909 (Hemiptera: Cercopidae on Brachiaria ruziziensis (Germain & Evard under field conditions. A total of 0, 4, 8, 12, or 16 M. spectabilis adults per plot were maintained for 6 days. Thereafter, the insects were removed from the plant, and the following parameters were evaluated: chlorophyll content, damage score, dry as well as fresh weights, percentage of shoots’ dry matter, and the forage’s ability to regrow. The chlorophyll content was significantly reduced; the damage score and percentage of dry matter in plants increased depending on the increased insect infestation density after 6 days of exposure. In contrast, no change was observed on the B. ruziziensis fresh and dry weights as well as the regrowth capacity depending on the M. spectabilis infestation densities. Attacks by 8 adult M. spectabilis per clump of B. ruziziensis with an average of 80 tillers for 6 days were sufficient to reduce the chlorophyll content and the functional plant loss index. This density can be a reference for spittlebug integrated management in Brachiaria.

  17. Weeds in Organic Fertility-Building Leys: Aspects of Species Richness and Weed Management

    Directory of Open Access Journals (Sweden)

    Thomas F. Döring

    2017-02-01

    Full Text Available Legume-based leys (perennial sod crops are an important component of fertility management in organic rotations in many parts of Europe. Despite their importance, however, relatively little is known about how these leys affect weed communities or how the specific composition of leys may contribute to weed management. To determine whether the choice of plant species in the ley affects weeds, we conducted replicated field trials at six locations in the UK over 24 months, measuring weed cover and biomass in plots sown with monocultures of 12 legume and 4 grass species, and in plots sown with a mixture of 10 legume species and 4 grass species. Additionally, we monitored weed communities in leys on 21 organic farms across the UK either sown with a mixture of the project species or the farmers’ own species mix. In total, 63 weed species were found on the farms, with the annuals Stellaria media, Sonchus arvensis, and Veronica persica being the most frequent species in the first year after establishment of the ley, while Stellaria media and the two perennials Ranunculus repens and Taraxacum officinale dominated the weed spectrum in the second year. Our study shows that organic leys constitute an important element of farm biodiversity. In both replicated and on-farm trials, weed cover and species richness were significantly lower in the second year than in the first, owing to lower presence of annual weeds in year two. In monocultures, meadow pea (Lathyrus pratensis was a poor competitor against weeds, and a significant increase in the proportion of weed biomass was observed over time, due to poor recovery of meadow pea after mowing. For red clover (Trifolium pratense, we observed the lowest proportion of weed biomass in total biomass among the tested legume species. Crop biomass and weed biomass were negatively correlated across species. Residuals from the linear regression between crop biomass and weed biomass indicated that at similar levels of crop

  18. Efeito de períodos de controle de plantas daninhas sobre o desenvolvimento inicial de plantas de eucalipto Effects of weed control periods on initial growth and development of eucalypt

    Directory of Open Access Journals (Sweden)

    R.E.B. Toledo

    2000-01-01

    Full Text Available O objetivo deste trabalho foi estudar os efeitos dos períodos de convivência e de controle de Brachiaria decumbens sobre o desenvolvimento inicial de clones de Eucalyptus grandis x Eucalyptus urophylla. Para isso, um ensaio foi conduzido, no município de Três Lagoas-MS, no período de janeiro a dezembro de 1997. Os tratamentos experimentais consistiram de diferentes épocas e períodos de convivência das plantas daninhas na cultura do eucalipto. As épocas foram divididas em dois grupos. No primeiro, a convivência se iniciava no transplante das mudas e era estendida até 28, 56, 84, 112, 140, 168, 224, 252 e 364 dias após. No segundo grupo, a convivência se iniciava aos 0, 28, 56, 84, 112, 140, 168, 224 e 252 dias após o transplante e era estendida até o final de um ano. As principais plantas daninhas que ocorreram na área experimental foram Brachiaria decumbens e Spermacocea latifola. As plantas jovens de eucalipto foram bastante suscetíveis à interferência das plantas daninhas, apresentando um período anterior à interferência inferior a 14-28 dias. Para assegurar o desenvolvimento da cultura, o período total de prevenção à interferência foi de 140 dias, e o período crítico de prevenção à interferência, de 14-28 a 140 dias após o transplante, considerando o índice de 5% de redução em diâmetro.A field trial was carried out in Três Lagoas-MS, Brazil, from January to December of 1997, to study the effects of control and coexistence period of Brachiaria decumbens on the growth of Eucalyptus grandis x Eucalyptus urophylla clones. The experimental design was a complete randomized block design, with four replications. The treatments consisted of different periods of weed-eucalypt association. The periods were divided in two groups. In the first one, the weed-eucalypt coexistence initiated during the eucalypt transplanting, continuing up to 28, 56, 112, 140, 168, 224, 252 and 364 days after it. In the second group, the

  19. Influência de Brachiaria brizantha nas características fisiológicas relacionadas a fotossíntese e uso eficiente da água em cana-de-açúcar Influence of Brachiaria brizantha in physiological characteristics related to photosynthesis and efficient use of water in sugarcane

    Directory of Open Access Journals (Sweden)

    L Galon

    2011-01-01

    Full Text Available O aumento da população das plantas daninhas eleva a habilidade competitiva dessas com as plantas cultivadas, podendo causar interferência nos aspectos fisiológicos das culturas. Objetivou-se com o trabalho avaliar a interferência de populações de Brachiaria brizantha nas características relacionadas a atividade fotossintética e o uso eficiente da água das cultivares de cana-de-açúcar RB72454, RB867515 e SP80-1816. Foi conduzido um experimento a campo, onde os tratamentos foram constituídos por 12 populações de plantas de B. brizantha que emergiram juntamente com a cultura. Aos 120 dias após a emergência da cana-de-açúcar foram realizadas as avaliações da concentração de CO2 subestomático (Ci - µmol mol-1, a atividade fotossintética (A - µmol m-2 s-1, a condutância estomática (Gs - mol m-1 s-1, a taxa de transpiração (E, a eficiência do uso da água (EUA e a massa seca da parte aérea (SDM - g por planta da cultura. Todas as variáveis fisiológicas e a massa seca da cultivar RB72454 foram afetadas pelo aumento da densidade das plantas de B. brizantha, bem como a transpiração da cultivar RB867515. A cultivar RB72454 apresenta menor habilidade competitiva com as plantas daninhas e a atividade fotossintética é limitada por fatores que reduzem o influxo de CO2 para o interior da folha.The increase in density of weeds increases also its competitive ability, which affects the physiological aspects of crops. This study aimed to evaluate the interference of increasing densities of Brachiaria brizantha over sugarcane varieties RB72454, RB867515 and SP80-1816 based on physiological variables related to the photosynthesis rate. For this, a field was installed, being treatments composed by 12 densities of the competitor, ranging from 0 to 112 plants m-2, emerged simultaneously to the crop. At 120 days after crop emergence the substomatal CO2 concentration (Ci - µmol mol-1, photosynthetic activity (A - µmol m-2 s-1

  20. Período de interferência de plantas daninhas em mandioca (Manihot esculenta no noroeste do Paraná Period of weed interference in cassava (Manihot esculenta in northwestern Parana

    Directory of Open Access Journals (Sweden)

    D.F. Biffe

    2010-01-01

    Full Text Available A mandioca é uma exploração agrícola importante no Estado do Paraná. No entanto, há limitadas informações relacionadas à interferência das plantas daninhas nessa cultura. Objetivou-se com este trabalho estimar o período crítico de prevenção à interferência (PCPI na cultura da mandioca (variedade Fécula Branca, nas condições edafoclimáticas do noroeste do Paraná. O experimento foi dividido em dois grupos de tratamentos: com períodos crescentes na presença de plantas daninhas (PAI; e com períodos crescentes na ausência de plantas daninhas (PTPI. Foram identificadas as espécies de plantas daninhas e densidades de infestação na área e calculada a importância relativa (IR, avaliando-se também o estande da cultura e a produtividade de raízes comerciais. As principais plantas daninhas presentes na área e que apresentaram os maiores valores de IR foram Cenchrus echinatus e Brachiaria decumbens. Aceitando-se uma tolerância de redução de produtividade de 5%, o PAI ajustado foi de 18 dias após o plantio da cultura, e o PTPI, de 100 dias. Concluiu-se que o PCPI da cultura para as condições edafoclimáticas do noroeste do Paraná situa-se entre 18 e 100 dias após o plantio.Although cassava is a major agribusiness crop in Paraná, technical information related to weed interference in this crop is limited. This work aimed to evaluate the critical period of weed interference (PCPI in cassava (var. Fécula Branca, for local climate and soil under northwestern Paraná conditions. The experiment was constituted of two groups: the first with increasing periods of weed interference (PAI and the second with increasing periods without weed interference (PTPI. Main weed species in the area were identified and accounted for densities and relative importance (RI during the cycle; crop stand and commercial root yield were also evaluated. The highest RI values were found for Cenchrus echinatus and Brachiaria decumbens. Considering a

  1. Plantas de cobertura no controle de plantas daninhas na cultura do tomate em plantio direto Cover crops used to control weeds under the no-tillage tomato production system

    Directory of Open Access Journals (Sweden)

    A.C. Silva Hirata

    2009-01-01

    Full Text Available O plantio direto do tomateiro é um sistema que busca maior sustentabilidade, porém são escassas as informações sobre o manejo de plantas daninhas nessa nova modalidade de cultivo. O objetivo deste trabalho foi avaliar cinco tipos de cobertura do solo (Brachiaria decumbens, B. ruziziensis, Pennisetum glaucum, comunidade infestante e tratamento sem cobertura vegetal para plantio direto do tomateiro rasteiro, conduzido no sistema meia estaca, em complementação ao controle químico com herbicidas. P. glaucum foi a espécie que proporcionou maior cobertura do solo até a colheita do tomate; todavia, a taxa de decomposição da palha foi maior que a das demais coberturas. As coberturas de solo compostas pelas gramíneas forrageiras B. decumbens, B. ruziziensis e Pennisetum glaucum reduziram a densidade e a massa seca das plantas daninhas. O uso da comunidade infestante para obtenção de palha promoveu reduzida cobertura do solo e elevada emergência de plantas daninhas, semelhantes às do solo sem cobertura. B. decumbens apresentou rebrota durante o ciclo do tomateiro, o que não ocorreu com B. ruziziensis.Tomato no tillage system is a more sustainable system. However, information about weed management in this new cultivation modality is scarce. The objective of this work was to evaluate five vegetation covers (Brachiaria decumbens, B. ruziziensis, Pennisetum glaucum, community weed and the treatment without vegetable covering for no tillage system of the staked processing tomato crop combined with weed chemical control. P. glaucum provided the most soil cover to the tomato crop, although straw decomposition rate was higher than those of the other covers. The soil cover by the forage grasses B. decumbens, B. ruziziensis and Pennisetum glaucum reduced the density and dry mass of the weeds. The use of the community weeds for straw obtaining promoted reduced covering of the soil and larger emergency of weeds, similar to the treatment without

  2. Eficácia do herbicida oxyfluorfen com a cobertura de palha no controle de plantas daninhas Efficacy of oxyfluorfen with straw cover in controlling weeds

    Directory of Open Access Journals (Sweden)

    E. Negrisoli

    2009-03-01

    Full Text Available A palha pode alterar a dinâmica do herbicida oxyfluorfen no sistema de cana-crua; assim, este trabalho teve por objetivo avaliar a eficácia do oxyfluorfen em condições de casa de vegetação, com a cobertura de palha, no controle das plantas daninhas que ocorrem em cana-crua. Foram avaliadas as espécies de Brachiaria decumbens, Ipomoea grandifolia, Ipomoea quamoclit e Merremia cissoides. A dose utilizada do oxyfluorfen foi de 3 L ha-1 (720 g i.a. ha-1. Os tratamentos constaram de diferentes posicionamentos do herbicida e condições antes e após a aplicação. A porcentagem de controle das plantas daninhas foi avaliada aos 12, 20, 26, 33 e 38 DAA. Os maiores índices de controle aos 38 DAA, independentemente da planta daninha estudada, foram alcançados quando se aplicou oxyfluorfen em tratamentos com a presença de palha em cobertura, com ou sem umidade. No entanto, os resultados obtidos nos demais tratamentos mostraram-se eficientes no controle das diferentes espécies de plantas daninhas estudadas.Straw can change the dynamics of the herbicide oxyfluorfen in the raw sugarcane system. Thus, this study aimed to assess the effectiveness of oxyfluorfen with straw cover in controlling weeds in raw sugarcane under greenhouse conditions. The species Brachiaria decumbens, Ipomoea grandifolia, Ipomoea quamoclit and Merremia cissoids were evaluated and the dose used was oxyfluorfen 3 L ha-1 (720 g .i.a. ha-1. Treatments consisted of different herbicide positions and conditions before and after application. Weed control percentage was evaluated at 12, 20, 26, 33 and 38 DAA. The highest control rates at 38 DAA, regardless of the weed studied, were reached when oxyfluorfen was applied in treatments with the cover straw, with or without humidity. However, the results obtained in the other treatments were effective in controlling the different weed species studied.

  3. Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia

    Directory of Open Access Journals (Sweden)

    Jaumer Ricaurte

    2007-09-01

    Full Text Available En un Haplustox de los Llanos Orientales de Colombia se evaluaron durante 41 meses 6 genotipos de Brachiaria con resistencia variable a niveles altos de Al+3 en dos niveles de nutrientes. Los genotipos con resistencia media y alta mantuvieron altas producciones de biomasa aérea en los primeros meses, decrecieron a valores medios y estables hacia los 21 meses. La producción de biomasa y longitud de raíces en los genotipos de Brachiaria y especies de sabana nativa fue mayor en época lluviosa, con alta producción en los primeros 5 cm del perfil de suelo. Las gramíneas de la sabana nativa y B. decumbens CIAT 606 (altamente resistente a Al+3 generaron raíces finas y menor biomasa de raíces. Durante la época seca los genotipos de Brachiaria con resistencia media y alta a aluminio generaron raíces más profundas que la sabana nativa. La época seca indujo una producción de longitud y biomasa de raíces proporcionalmente más profundas que la lluviosa, tanto en genotipos de Brachiaria con resistencia media y alta a aluminio como en especies de la sabana nativa.

  4. Interferência de plantas daninhas no cultivo da melancia Weeds interference periods in watermelon crop

    Directory of Open Access Journals (Sweden)

    Cleber Daniel de G Maciel

    2008-03-01

    crop is an agricultural activity explored regionally, representing one of the most important sources of family income in small cities of the Médio Paranapanema, São Paulo State, Brazil, where nowadays, significant changes in the yield process are verified, changing from intensive labor to the use of promising technologies, as weed management, for instance. An experiment was carried out at Oscar Bressane municipal district, São Paulo State, Brazil, to study the weed interference on watermelon cultivation, in 2002/2003. Statistical procedure was based on randomized blocks with ten treatments and four replications, represented by plots with useful area of 18 m², containing four water melon plants and infestation of Sidaspp, Brachiaria humidicola, Commelina benghalensisand Portulaca oleraceaspecies. Weed infestation was estimated through randomized samples from the plots, using an iron drained square with 0,5 m sides. Treatments consisted of checks with and without hand weeded and different periods of weeds control, so that, crop was sustained in weeds presence or absence up to 7; 14; 28; 56 and 63 days after emergency (DAE. Initial period occurrence of possible coexistence greater than the final period established the Critical Period of Interference Prevention from the 9th to the 13th days (CPIP = 9-13 DAE. The reduction in yield due to the weed interference during all water melon crop cycle was about 41,4%. The diameter and thickness of fruits peel were also influenced by the coexistence with weed infestation during all the crop cycle, with decreases of 7,9% and 23,3%, respectively, against the characteristics length and diameter of branch and ºBrix of fruits pulp, when significant differences were not observed.

  5. Opportunities for biological weed control in Europe

    NARCIS (Netherlands)

    Scheepens, P.C.; Müller-Schärer, H.; Kempenaar, C.

    2001-01-01

    The development and application of biological weed control offer greatopportunities not only for farmers, nature conservationists and othervegetation managers but also for institutions and companies that wish tosell plant protection services and products, and for the general publicthat demands safe

  6. Bioenergy potential of eight common aquatic weeds

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, S.A.; Nipaney, P.C.; Schaumberg, G.D. (Pondicherry (Central) Univ. (IN). Salim Ali School of Ecology)

    1990-01-01

    Eight common aquatic weeds Salvinia molesta, Hydrilla verticillata, Nymphaea stellata, Azolla pinnata, Ceratopteris sp. Scirpus sp. Cyperus sp, and Utricularia reticulata were digested anaerobically to produce methane. The carbon to nitrogen (C/N) ratio, carbon to phosphorus (C/P) ratio, and the volatile solids (VS) content of the weeds varied widely. No trend between these factors and the methane yield was discernable; the possible reasons are discussed. The energy potential of the weeds per unit area of the weed crop was worked out. Natural stands of salvinia, such as the one employed in the present investigation, would yield energy (methane) of the order of 10{sup 8} Kcal/ha/yr. (author).

  7. Alien species in the Finnish weed flora

    Directory of Open Access Journals (Sweden)

    T. HYVÖNEN

    2008-12-01

    Full Text Available The present study aimed at assessing the invasion of alien weed species in Finland based on a review of their occurrence in the Finnish weed flora. The evaluation was conducted for the three phases of the invasion process, i.e. introduction, naturalization and invasion. The literature review revealed that 815 alien weed species occur in Finland of which 314 are regarded as naturalized. Based on their occurrence in different climate zones, the risk of naturalization of new harmful alien weed species was deemed low for those species not currently found in Finland, but higher for species occurring as casual aliens in Finland. In the latter group, 10 species of concern were detected. Exploration of the distribution patterns of naturalized species within Finland revealed species occupancy to be dependent on the residence time of the species. Established neophytes can be expected to extend their ranges and to increase occupation of agricultural habitats in the future.;

  8. WHITE BLISTER SPECIES (Albuginaceae ON WEEDS

    Directory of Open Access Journals (Sweden)

    Karolina Vrandečić

    2011-06-01

    Full Text Available The obligate fungi inside the family Albuginaceae are widespread world wide and cause white rust or white blister disease. Mycopopulation of weeds has been researched within the project „The role of weeds in epidemiology of row-crop diseases“. The aim of this research was to identify white blister species occurring on weeds in Eastern Croatia. Weed plants with disease symptoms characteristic for white blister species have been collected since 2001 on location Slavonia and Baranja country. Determination of white blister species was based on morphological characters of pathogen and the host. Wilsoniana bliti was determined on Amaranthus retroflexus and Amaranthus hybridus leaves. Capsella bursa pastoris is a host for Albugo candida. Ambrosia artemisiifolia is a host for Pustula sp. and Cirsium arvense was found to be host for Pustula spinulosa. Wilsoniana portulaceae was determined on Portulaca oleracea.

  9. Impact of fungicides on weed growth

    Directory of Open Access Journals (Sweden)

    Nordmeyer, Henning

    2014-02-01

    Full Text Available The study has shown that fungicides influence the growth of weeds. The competition against crops will be substantially reduced. Bioassays in a climate chamber variation in temperature as well as different lightning phases and microplot trials under semi field levels were carried out to investigate the influence of fungicides on weed growth. Selected weed species (Alopecurus myosuroides, Viola arvensis, Galium aparine, Stellaria media, Lamium purpureum have been examined with different dose rates of fungicides (Adexar, Bravo 500, Diamant, Crupozin flüssig. Weed species showed a different sensitivity. There were leaf discoloration, contractions and growth inhibition. In some cases using common practise dose rates of fungicides more than 70% growth inhibition could be estimated 14 days after application in comparison to the untreated control. Effects were much stronger in bioassays than in semi field trials.

  10. Viruses in weeds in Dioscorea yam

    African Journals Online (AJOL)

    ACSS

    East, Central and Southern Africa (FAOSTAT,. 2009) ... This study was conducted in the Guinea Savanna zone, which is the ... Weed hosts of yam viruses in the wet season of 2009 in northern Nigeria .... be due to differences in the surrounding.

  11. Produtividade e valor nutritivo da Brachiaria brizantha cv. Marandu em um sistema silvipastoril Productivity and nutritional value of Brachiaria brizantha cv. Marandu in a silvopastoral system

    Directory of Open Access Journals (Sweden)

    L.F. Sousa

    2007-08-01

    Full Text Available O experimento foi realizado em sistema silvipastoril (Ssp localizado no bioma de Cerrado, no município de Lagoa Santa, Minas Gerais, no ano agrícola de 2004-2005. Avaliou-se a influência do Ssp composto pela arbórea bolsa-de-pastor (Zeyheria tuberculosa sobre os parâmetros produção, atributos morfogênicos, composição bromatológica e valor nutritivo da gramínea Brachiaria brizantha cv. Marandu, e os efeitos sobre as condições microclimáticas. O delineamento experimental foi em blocos ao acaso, com cinco blocos (épocas de corte, dois tratamentos (T1 - B. brizantha cv. Marandu sombreada com a Z. tuberculosa e T2 - B. brizantha cv. Marandu, a pleno sol e três repetições (parcelas. O sombreamento proporcionado pela Z. tuberculosa, apesar de reduzir a produção de matéria seca (MS da gramínea, favoreceu o aumento do teor de proteina bruta (PB e não alterou a produção de PB/ha e nem afetou a concentração de FDN. Os teores de FDA foram mais altos que os encontrados a pleno sol, o que provavelmente resultou em menor degradabilidade in vitro da MS e da matéria orgânica, não alterando a degradabilidade efetiva.The experiment was carried out in a Silvopastoral system (Sps located in Brazilian Savannah, Lagoa Santa county, Minas Gerais State, during the agricultural year of 2004-2005. It was studied the influence of Sps formed by "Bolsa de Pastor" (Zeyheria tuberculosa on the production, morphogenic attributes, bromatological composition and nutritional value of the graminaceous Brachiaria brizantha cv. Marandu as well as on the microclimatic aspects. The Sps was established in 1982, in a red-yellow latossol by the natural regeneration process. The experiment was based on a randomized block design, with 5 blocks (cutting times, 2 treatments (T1 - B. brizantha cv. Marandu shaded by Z. tuberculosa and T2 - B. brizantha cv. Marandu at open sky and three repetitions (plots. Although the DM production of the graminaceous in the Sps

  12. Crop diversity prevents serious weed problems

    DEFF Research Database (Denmark)

    Melander, Bo

    2016-01-01

    Weed management in organic crop production could benefit from more diversification of today’s cropping systems. However, the potential of diversification needs better documentation and solid suggestions for employment in practise must be identified.......Weed management in organic crop production could benefit from more diversification of today’s cropping systems. However, the potential of diversification needs better documentation and solid suggestions for employment in practise must be identified....

  13. WEED MANAGEMENT AND CONTROL IN POTATOES

    Directory of Open Access Journals (Sweden)

    Marcelo Cleón de Castro Silva

    2011-07-01

    Full Text Available This review shows instructions to potatoes' farmer about behavior of the weeds and how to manage them so as to minimize loss of productivity through the use of control strategies for potato crop. The prevention consists in adoption of practices that prevents entry of unwanted species of weeds in the planting site. The control reduces the infestation of these species, but this practice does not eradicate them completely. However, it needs to control the weeds before the area preparation for planting the tubers until complete closure of the soil by shoots of potatoes during the critical period. After covering the soil, the potato crop does not suffer negative interference caused by weeds. The cultural practices include a good plane for harvest, plant crop rotation, the planting of appropriate plants for covering the soil, the ideal space to the planting and the correct time to potato planting. The control must be efficient to reduce the number of weeds in the area to avoid economic losses to farmers. It is necessary to establish weed management strategies in order to maintain sustainable farming systems, preserving the environment and quality of life of the farmer.

  14. Weed detection using unmanned aircraft vehicles

    Directory of Open Access Journals (Sweden)

    Pflanz, Michael

    2014-03-01

    Full Text Available In contrast to agricultural remote sensing technologies, which are based on images from satellites or manned aircrafts, photogrammetry at low altitude from unmanned aircraft vehicles lead to higher spatial resolution, real-time processing and lower costs. Moreover multicopter aircrafts are suitable vehicles to perform precise path or stationary flights. In terms of vegetation photogrammetry this minimises motion blur and provide better image overlapping for stitching and mapping procedures. Through improved image analyses and through the recent increase in the availability of powerful batteries, microcontrollers and multispectral cameras, it can be expected in future that spatial mapping of weeds from low altitudes will be promoted. A small unmanned aircraft vehicle with a modified RGB camera was tested taking images from agricultural fields. A microcopter with six rotors was applied. The hexacopter in particular is GPS controlled and operates within predefined areas at given altitudes (from 5 to 10 m. Different scenarios of photogrammetrically weed detection have been carried out regarding to variable altitude, image resolution, weed and crop growth stages. First experiences with microcopter showed a high potential for site-specific weed control. Images analyses with regards to recognition of weed patches can be used to adapt herbicide applications to varying weed occurrence across a field.

  15. Effect of inclusion of oyster mushroom substrate on the in vitro fermentation kinetics of Brachiaria brizantha hay

    Directory of Open Access Journals (Sweden)

    Ricardo da Silva Oliveira

    2015-07-01

    Full Text Available The objective of this study was to evaluate the effect of inclusion of exhausted substrate of Pleurotus ostreatus on the in vitro fermentation of Brachiaria brizantha hay-based diets. The experiment was conducted using the semi-automated gas production technique. The ruminal inoculum was collected from three fistulated cattle kept on Brachiaria brizantha pasture. Brachiaria brizantha hay and exhausted substrate of Pleurotus production were used for composition of the diets: ES (100% exhausted substrate, BH (100% Brachiaria brizantha hay, ES5 (5% ES + 95% BH, ES20 (20% ES + 80% BH, and ES30 (30% ES + 70% BH. The experimental design was a 5x3 factorial scheme consisting of five treatments and three ruminal inocula. The degradation kinetics of dry matter (DM was determined after 96 hours of fermentation [D (96h]. No significant differences in the cumulative volume of gas (A were observed between BH (262.6 mL/g DM, ES5 (284.3 mL/g MS, ES20 (256.6 mL/g MS and ES30 (261.7 mL/g MS, indicating that inclusion of the substrate did not affect hay fermentation. A lower gas volume (165.9 mL and lower degradability (52% were observed for the ES diet, showing a lower nutritional value of this substrate compared to Brachiaria brizantha hay, probably due to the action of enzymes that degrade structural carbohydrates found in the mycelia of Pleurotus. The ES diet exhibited a shorter colonization time (L=2.6 h; P<0.05, a finding that may be attributed to the interaction between the mycelium and substrate, facilitating initial colonization. The inclusion of exhausted substrate did not increase microbial growth or degradation compared to the BH diet, but seems to have favored initial colonization of this substrate. The use of ES does not negatively affect colonization and may be used as an ingredient of ruminant diets.

  16. ORGANIC FERTILIZER AS PHOSPHORUS SUPPLIER FOR Brachiaria brizantha CV. MARANDÚ FERTILIZANTE ORGÂNICO COMO FONTE DE FÓSFORO NO CULTIVO INICIAL DE Brachiaria brizantha CV. MARANDÚ

    Directory of Open Access Journals (Sweden)

    Diego Henriques Santos

    2010-05-01

    Full Text Available

    Phosphorus is considered an essential element for plants, but it is found in low amounts in Brazilian soils, mainly in areas destined to pastures, and the application of organic matter contributes to the improvement of physical, chemical and biological soil attributes. The research had the objective of evaluating the application effects of the Bokashi organic compound on soil macro and micronutrients contents and leaves, as well as on Brachiaria brizantha cv. Marandú dry mass yield, evaluating the potential of the organic fertilizer as phosphorus source, in comparison with conventional chemical fertilizers. Different organic compound doses supplied the soil with 17 kg P2O5 ha-1, 34 kg P2O5 ha-1, 68 kg P2O5 ha-1, 136 kg P2O5 ha-1, and 204 kg P2O5 ha-1, comparing it with the conventional chemical fertilizer and the control. The results revealed that the organic fertilizer Bokashi can adequately replace the conventional chemical fertilizer of Brachiaria brizantha cv. Marandú, supplying the soil and plant with appropriate nutrients levels and maintaining the dry mass yield.

    KEY-WORDS: Organic matter; organic fertilizers; plants mineral nutrition; Bokashi

  17. Chemical weed control in Spinach (Spiniacia oleracea

    Directory of Open Access Journals (Sweden)

    A. Modhej

    2016-03-01

    Full Text Available Introduction Spinach (Spinacia oleracea is an annual plant of family Chenopodiaceae. It is cultivated in temperate and cold regions in Khouzestan in autumn and winter. Weeds are the main problems that limit the production of vegetables. Competition ability of spinach against weeds is very low and weeds cause the loss of quality and quantity in this plant. Weeds reduce germination and establishment and growth of spinach. Weed management in spinach should be done at the beginning of the season. Hand weeding is the best way to control weeds spinach, although due to the high cost it is not cost effective, but is steel common in large areas. Weed control spinach, using chemical methods, the number of weeds are kept below the threshold of economic damage. Materials and Methods The experiment was conducted in a randomized complete block design with 15 treatments and three replications. Treatments included pre-plant application of EPTC at 5 and 6 lit ha-1, pre-plant application of Trifluralin at 2 lit ha-1, pre-plant and pre-emergence application of Pendimethalin at 3 lit ha-1, pre-emergence and post-emergence application of Meteribouzin at 300 g ha-1, pre-emergence and post-emergence application of Meteribouzin at 400 g ha-1, pre-emergence and post-emergence application of Imazethapyr at 0.7 lit ha-1, pre-emergence and post-emergence application of Imazethapyr at 1 lit ha-1, weedy and weed free checks. Each plot the size of 2.5 × 2 meters and 10 row cultivation with distances between rows of 15 cm and the distance between the plants 25 cm and the sowing depth was 3 cm. The herbicide treatments were applied to the back sprayer with Flat fan nozzle with volume of consumption of 240 lit ha-1 solution. The final harvest was about 50 days after emergence. Sampling of weeds 10 days before harvest was performed with using quadrate 0.5 ×0.5. Results Discussion Important broad-leaf and narrow leaf weeds observed in the field, included field bindweed

  18. On weed competition and population dynamics : considerations for crop rotations & organic farming

    NARCIS (Netherlands)

    Mertens, S.K.

    2002-01-01

    Key words: organic farming, weeds, weed management, weed ecology, weed diversity, matrix population model, elasticity analysis, neighbourhood model, survey, crop row spacing, mechanical hoe, harrow, Polygonum convolvulus ,

  19. Combining a weed traits database with a population dynamics model predicts shifts in weed communities.

    Science.gov (United States)

    Storkey, J; Holst, N; Bøjer, O Q; Bigongiali, F; Bocci, G; Colbach, N; Dorner, Z; Riemens, M M; Sartorato, I; Sønderskov, M; Verschwele, A

    2015-04-01

    A functional approach to predicting shifts in weed floras in response to management or environmental change requires the combination of data on weed traits with analytical frameworks that capture the filtering effect of selection pressures on traits. A weed traits database (WTDB) was designed, populated and analysed, initially using data for 19 common European weeds, to begin to consolidate trait data in a single repository. The initial choice of traits was driven by the requirements of empirical models of weed population dynamics to identify correlations between traits and model parameters. These relationships were used to build a generic model, operating at the level of functional traits, to simulate the impact of increasing herbicide and fertiliser use on virtual weeds along gradients of seed weight and maximum height. The model generated 'fitness contours' (defined as population growth rates) within this trait space in different scenarios, onto which two sets of weed species, defined as common or declining in the UK, were mapped. The effect of increasing inputs on the weed flora was successfully simulated; 77% of common species were predicted to have stable or increasing populations under high fertiliser and herbicide use, in contrast with only 29% of the species that have declined. Future development of the WTDB will aim to increase the number of species covered, incorporate a wider range of traits and analyse intraspecific variability under contrasting management and environments.

  20. Mechanical weed control in organic winter wheat

    Directory of Open Access Journals (Sweden)

    Euro Pannacci

    2017-12-01

    Full Text Available Three field experiments were carried out in organic winter wheat in three consecutive years (exp. 1, 2005-06; exp. 2, 2006- 07; exp. 3, 2007-08 in central Italy (42°57’ N - 12°22’ E, 165 m a.s.l. in order to evaluate the efficacy against weeds and the effects on winter wheat of two main mechanical weed control strategies: i spring tine harrowing used at three different application times (1 passage at T1, 2 passages at the time T1, 1 passage at T1 followed by 1 passage at T1 + 14 days in the crop sowed at narrow (traditional row spacing (0.15 m; and ii split-hoeing and finger-weeder, alone and combined at T1, in the crop sowed at wider row spacing (0.30 m. At the time T1 winter wheat was at tillering and weeds were at the cotyledons-2 true leaves growth stage. The experimental design was a randomized block with four replicates. Six weeks after mechanical treatments, weed ground cover (% was rated visually using the Braun-Blanquet coverabundance scale; weeds on three squares (0.6×0.5 m each one per plot were collected, counted, weighed, dried in oven at 105°C to determine weed density and weed above-ground dry biomass. At harvest, wheat ears density, grain yield, weight of 1000 seeds and hectolitre weight were recorded. Total weed flora was quite different in the three experiments. The main weed species were: Polygonum aviculare L. (exp. 1 and 2, Fallopia convolvulus (L. Á. Löve (exp. 1 and 3, Stachys annua (L. L. (exp. 1, Anagallis arvensis L. (exp. 2, Papaver rhoeas L. (exp.3, Veronica hederifolia L. (exp. 3. In the winter wheat sowed at narrow rows, 2 passages with spring-tine harrowing at the same time seems to be the best option in order to reconcile a good efficacy with the feasibility of treatment. In wider rows spacing the best weed control was obtained by split hoeing alone or combined with finger-weeder. The grain yield, on average 10% higher in narrow rows, the lower costs and the good selectivity of spring-tine harrowing

  1. Developments in physical weed control in Northwest Europe

    Directory of Open Access Journals (Sweden)

    Riemens, Marieen

    2016-02-01

    Full Text Available In North West Europe there is an increasing need for advanced weed control methods. This paper gives an overview of the developments in physical weed control methods. Current innovations in interrow weeding focus on systems that take over the steering function of the driver in order to make them more precise and reduce crop losses. The latest developments in intrarow weeding techniques involve technologies that automatically detect and classify crop and weed plants and use this information to guide a weeding device. Several commercially available examples are presented.

  2. Ecological Intensification Through Pesticide Reduction: Weed Control, Weed Biodiversity and Sustainability in Arable Farming.

    Science.gov (United States)

    Petit, Sandrine; Munier-Jolain, Nicolas; Bretagnolle, Vincent; Bockstaller, Christian; Gaba, Sabrina; Cordeau, Stéphane; Lechenet, Martin; Mézière, Delphine; Colbach, Nathalie

    2015-11-01

    Amongst the biodiversity components of agriculture, weeds are an interesting model for exploring management options relying on the principle of ecological intensification in arable farming. Weeds can cause severe crop yield losses, contribute to farmland functional biodiversity and are strongly associated with the generic issue of pesticide use. In this paper, we address the impacts of herbicide reduction following a causal framework starting with herbicide reduction and triggering changes in (i) the management options required to control weeds, (ii) the weed communities and functions they provide and (iii) the overall performance and sustainability of the implemented land management options. The three components of this framework were analysed in a multidisciplinary project that was conducted on 55 experimental and farmer's fields that included conventional, integrated and organic cropping systems. Our results indicate that the reduction of herbicide use is not antagonistic with crop production, provided that alternative practices are put into place. Herbicide reduction and associated land management modified the composition of in-field weed communities and thus the functions of weeds related to biodiversity and production. Through a long-term simulation of weed communities based on alternative (?) cropping systems, some specific management pathways were identified that delivered high biodiversity gains and limited the negative impacts of weeds on crop production. Finally, the multi-criteria assessment of the environmental, economic and societal sustainability of the 55 systems suggests that integrated weed management systems fared better than their conventional and organic counterparts. These outcomes suggest that sustainable management could possibly be achieved through changes in weed management, along a pathway starting with herbicide reduction.

  3. Abnormal spindle orientation during microsporogenesis in an interspecific Brachiaria (Gramineae hybrid

    Directory of Open Access Journals (Sweden)

    Andréa Beatriz Mendes-Bonato

    2006-01-01

    Full Text Available This paper reports a case of abnormal spindle orientation during microsporogenesis in an interspecific hybrid of the tropical grass Brachiaria. In the affected plant, prophase I was normal. In metaphase I, bivalents were regularly co-oriented but distantly positioned and spread over the equatorial plate. In anaphase I, chromosomes failed to converge into focused poles due to parallel spindle fibers. As a consequence, in telophase I, an elongated nucleus or several micronuclei were observed in each pole. In the second division, the behavior was the same, leading to polyads with several micronuclei. A total of 40% of meiotic products were affected. The use of this hybrid in production systems needing good-quality seeds is discussed.

  4. Study on mutagenesis of Signal grass (Brachiaria decumbens) by gamma irradiation

    International Nuclear Information System (INIS)

    Abdul Rahim Harun; Shuhami Shamsuddin; Ghazali Hussin

    2000-01-01

    Before starting experiments on induced mutation breeding of crops it is essential to carry out radiosensitivity test when determining the optimum doses of every plant genotype. Factors such as moisture content and oxsigen availability could influence mutagenesis process through ionizing radiation. Many methodologies could be used for determining the effect of radiation on seed of plants such as the 'Sandwich blotter technique' and 'Sand bed technique'. Different species have different sensitivity to mutagenic agents. Even varieties of the same species show variations in sensitivity to irradiation. Brachiaria clecumbens was found to be less sensitive to gamma radiation. At a dose of 800 Gy, the percentage reduction in growth was around 40%. Early result has shown that the optimum doses for mutagenesis was between 700 to 900 Gy

  5. The possible allelopathic effects of Brachiaria decumbens on initial development of root stock of Citrus limonia

    OpenAIRE

    Souza, L. S.; Velini, E. D.; Martins, D.; Rosolem, C. A.

    1997-01-01

    Foram estudados os possíveis efeitos alelopáticos da incorporação da matéria seca da parte aérea de Brachiaria decumbens, ao substrato, nas concentrações de 0, 1,5 e 3,0% (p/p) sobre o crescimento inicial de limão cravo (Citrus limonia Osbeck), em casa-de-vegetação. Foram determinados os parâmetros biométrico s e algumas propriedades físico-químicas da solução do solo. A maior quantidade de matéria seca incorporada causou redução de 44, 42, 57 e 55% das médias da altura, teor de clorofila, ár...

  6. Comparative effect of selenium and selenium tolerant microbes on brachiaria reptans l. growth

    International Nuclear Information System (INIS)

    Yasin, M.; Faisal, M.

    2014-01-01

    Brachiaria reptans L. is an annual grass. It is good fodder grass which is distributed in tropical Asia, Kenya, Pakistan and India and introduced throughout the tropics. In present study we determine the growth correlation among B. reptans, selenium (Se) and two Se tolerant bacteria (Bacillus licheniformis-YAP7 and Bacillus cereus-YAP6). Plants treated with Se showed a significant decrease in shoot length (33%) and fresh biomass (41%) compared to control. When plants were co-cultivated in the presence of bacteria or Se and bacteria both the shoot length increased (16-34%) significantly compared to control. B. reptans plants treated with Se have shown a significant decrease in peroxidase contents (59%) compared to control. However, bacterial inoculation of Se treated plants resulted in significant increase in peroxidase contents (113-171%). Selenium treatment caused increase in leaf soluble protein contents compared to control. In conclusion, bacteria can enhance B. reptans growth under Se stress. (author)

  7. Photosynthetic light response of the C4 grasses Brachiaria brizantha and B. humidicola under shade

    Directory of Open Access Journals (Sweden)

    Dias-Filho Moacyr Bernardino

    2002-01-01

    Full Text Available Forage grasses in tropical pastures can be subjected to considerable diurnal and seasonal reductions in available light. To evaluate the physiological behavior of the tropical forage grasses Brachiaria brizantha cv. Marandu and B. humidicola to low light, the photosynthetic light response and chlorophyll contents of these species were compared for plants grown outdoors, on natural soil, in pots, in full sunlight and those shaded to 30 % of full sunlight, over a 30-day period. Both species showed the ability to adjust their photosynthetic behavior in response to shade. Photosynthetic capacity and light compensation point were lower for shade plants of both species, while apparent quantum yield was unaffected by the light regime. Dark respiration and chlorophyll a:b ratio were significantly reduced by shading only in B. humidicola. B. humidicola could be relatively more adapted to succeed, at least temporarily, in light-limited environments.

  8. Ingestive Behavior of Heifers Supplemented with Glycerin in Substitution of Corn on Brachiaria brizantha Pasture.

    Science.gov (United States)

    Facuri, L M A M; Silva, R R; da Silva, F F; de Carvalho, G G P; Sampaio, C B; Mendes, F B L; Lisboa, M M; Barroso, D S; Carvalho, V M; Pereira, M M S

    2014-11-01

    The objective was to evaluate the ingestive behavior of crossbred heifers finished on a Brachiaria brizantha cv. Marandu pasture receiving four levels of glycerin in their supplementation. Thirty-six crossbred heifers with average initial weight of 264.83±3.83 kg and 20 months of age were distributed into a completely randomized design with four treatments and nine replications: control (0%), 4.82%, 10.12%, and 15.56% glycerin in the dry matter. The grazing time reduced linearly (p0.05). The number of rumination periods reduced linearly (p0.05) whereas the feed efficiency of neutral detergent fiber reduced linearly (p<0.05). Addition of glycerin in substitution of corn in supplements for animals managed on pastures does not influenced feed intake, but reduces the grazing time and increases the idle time. The supplementation also improves feed and rumination efficiencies.

  9. Weed control in rose-scented geranium (Pelargonium spp).

    Science.gov (United States)

    Kothari, Sushil K; Singh, Chandra P; Singh, Kamla

    2002-12-01

    Abstract: Field investigations were carried out during 1999 and 2000 to identify effective chemical/ cultural methods of weed control in rose-scented geranium (Pelargonium spp). The treatments comprised pre-emergence applications of oxyfluorfen (0.15, 0.20 and 0.25 kg AI ha(-1)) and pendimethalin (0.50, 0.75 and 1.00kg AI ha(-1)), successive hand weeding, hoeing and mulching using spent of lemon grass (at 5 tonnes ha(-1)) 45 days after planting (DAP), three hand-weedings 30, 60 and 90 DAP, weed-free (frequent manual weeding) and weedy control. Broad-leaf weeds were more predominant than grass and sedge weeds, accounting for 85.8% weed density and 93.0% weed dry weight in 1999 and 77.2% weed density and 93.9% weed dry weight in 2000. Unrestricted weed growth significantly reduced geranium oil yield, by 61.6% and 70.6% in 1999 and 2000, respectively. Pre-emergence application of pendimethalin (0.75-1.00 kgAI ha(-1)) or oxyfluorfen (0.25 kg AI ha(-1)), successive hand-weeding, hoeing and mulching and three hand-weedings were highly effective in reducing weed density and dry weight and gave oil yield comparable to the weed-free check. Application of oxyfluorfen (0.15 or 0.20 kg AI ha(-1)) and pendimethalin (0.50 kg AI ha(-1)) were less effective in controlling the weed species in geranium. None of the herbicides impaired the quality of rose-scented geranium oil measured in terms of citronellol and geraniol content.

  10. Losses through gases and effluent and nutritional value of Brachiaria decumbens with addition of soybean hulls

    Directory of Open Access Journals (Sweden)

    Carlos Clayton Oliveira Dantas

    2014-05-01

    Full Text Available The objective of this experiment was to evaluate the losses of nutrient through gases and effluents, the nutrient recovery, fermentation parameters and the chemical parameters of silages of Brachiaria decumbens with the addition of soybean hulls, testing five levels of inclusion: 0, 10, 20, 30 and 40% (as is, with five replications per treatment. After the standardization cut of the forage, performed at 5 cm from the soil level, the soil was fertilized with nitrogen and potassium in the form of ammonium sulfate and potassium chloride, respectively, at 60 kg/ha. After 60 days, the grass was cut at 10 cm from the soil and ensiled. Experimental silos with capacity of 10 liters with Bunsen valve were used. Silos had 3 kg of sand conditioned at the bottom for retention of the effluents. The results show that the contents of dry matter, crude protein, acid detergent insoluble fiber and total digestible nutrients presented positive linear behavior with the inclusion of soybean hulls. In the grass silages with addition of soybean hulls, there was greater recovery of dry matter in relation to the control silage, which is a reflection of the negative linear behavior for the values of losses of gases and effluent. There was quadratic behavior in the pH values and negative linear behavior for the ammonia N values and buffering capacity with the inclusion of the additive in the grass silage. Inclusion of soybean hulls is sufficient to improve the fermentation pattern and minimize the losses through gases and effluents, contributing to the nutrient recovery, in addition to promoting overall improvement of the nutritional value of Brachiaria grass silages.

  11. Influence of soil fertility on waterlogging tolerance of two Brachiaria grasses

    Directory of Open Access Journals (Sweden)

    Juan de la Cruz Jiménez

    2015-04-01

    Full Text Available As a consequence of global warming, rainfall is expected to increase in several regions around the world. This, together with poor soil drainage, will result in waterlogged soil conditions. Brachiaria grasses are widely sown in the tropics and, these grasses confront seasonal waterlogged conditions. Several studies have indicated that an increase in nutrient availability could reduce the negative impact of waterlogging. Therefore, an outdoor study was conducted to evaluate the responses of two Brachiaria sp. grasses with contrasting tolerances to waterlogging, B. ruziziensis (sensitive and B. humidicola (tolerant, with two soil fertility levels. The genotypes were grown with two different soil fertilization levels (high and low and under well-drained or waterlogged soil conditions for 15 days. The biomass production, chlorophyll content, photosynthetic efficiency, and macro- (N, P, K, Ca, Mg and S and micronutrient (Fe, Mn, Cu, Zn and B contents in the shoot tissue were determined. Significant differences in the nutrient content of the genotypes and treatments were found. An increase of redoximorphic elements (Fe and Mn in the soil solution occurred with the waterlogging. The greater tolerance of B. humidicola to waterlogged conditions might be due to an efficient root system that is able to acquire nutrients (N, P, K and potentially exclude phytotoxic elements (Fe and Mn under waterlogged conditions. A high nutrient availability in the waterlogged soils did not result in an improved tolerance for B. ruziziensis. The greater growth impairment seen in the B. ruziziensis with high soil fertility and waterlogging (as opposed to low soil fertility and waterlogging was possibly due to an increased concentration of redoximorphic elements under these conditions.

  12. Optical Sensing of Weed Infestations at Harvest.

    Science.gov (United States)

    Barroso, Judit; McCallum, John; Long, Dan

    2017-10-19

    Kochia ( Kochia scoparia L.), Russian thistle ( Salsola tragus L.), and prickly lettuce ( Lactuca serriola L.) are economically important weeds infesting dryland wheat ( Triticum aestivum L.) production systems in the western United States. Those weeds produce most of their seeds post-harvest. The objectives of this study were to determine the ability of an optical sensor, installed for on-the-go measurement of grain protein concentration, to detect the presence of green plant matter in flowing grain and assess the potential usefulness of this information for mapping weeds at harvest. Spectra of the grain stream were recorded continuously at a rate of 0.33 Hz during harvest of two spring wheat fields of 1.9 and 5.4 ha. All readings were georeferenced using a Global Positioning System (GPS) receiver with 1 m positional accuracy. Chlorophyll of green plant matter was detectable in the red (638-710 nm) waveband. Maps of the chlorophyll signal from both fields showed an overall agreement of 78.1% with reference maps, one constructed prior to harvest and the other at harvest time, both based on visual evaluations of the three green weed species conducted by experts. Information on weed distributions at harvest may be useful for controlling post-harvest using variable rate technology for herbicide applications.

  13. SHIFTING WEED COMPOSITIONS AND BIOMASS PRODUCTION IN SWEET CORN FIELD TREATED WITH ORGANIC COMPOSTS AND CHEMICAL WEED CONTROLS

    Directory of Open Access Journals (Sweden)

    Marulak Simarmata

    2015-10-01

    Full Text Available The objectives of the research were to study the shift of weed compositions in sweet corn field treated with organic compost and chemical weed controls and to compare the effect of treatment combinations on weed growth, weed biomass and sweet corn biomass. The research was conducted in Bengkulu, Indonesia, from April to July 2014. Results showed that the number of weed species decreased after the trials from 14 to 13. There was a shift in weed compositions because 5 species of weeds did not emerge after the trials, but 4 new species were found. Chemical weed control used a herbiside mixture of atrazine and mesotrione applied during postemergence was the most effective method to control weeds, which was observed on decreased weed emergence and weed biomass down to 22.33 and 25.00 percent of control, respectively. Subsequently, biomass production of sweet corn increased up to 195.64 percent at the same trials. Biomass of weeds and sweet corn were also affected by the organic composts. Weed biomass was inhibited by treatment of composted empty fruith bunches of oil palm, whereas significantly increased of sweet corn biomass were observed in the plots of organic manure.

  14. Weed seed germination in winter cereals under contrasting tillage systems

    DEFF Research Database (Denmark)

    Scherner, Ananda

    2015-01-01

    to accumulate in the top soil layer and timing of herbicide applications sometimes seems to target the emergence pattern of these weeds poorly. In contrast to the management of most diseases and pests, weed management should be considered in a time frame. The abilities to produce above and below ground...... of weeds. An important component in IWM is to understand and ultimately predict weed emergence patterns in relation to the cropping system and the tillage method applied. A better understanding of the cumulative emergence patterns of weed species in winter crops under different tillage regimes will help......Grass weeds and Gallium aparine are major weed problems in North European arable cropping systems with high proportions of winter crops, especially winter wheat (Clarke et al., 2000; Melander et al., 2008). Problems are accentuated where inverting tillage is omitted, as weed seeds tend...

  15. Competição entre feijoeiros e plantas daninhas em função do tipo de crescimento dos cultivares Competition between the common bean and weed in function of cultivar growth type

    Directory of Open Access Journals (Sweden)

    I.R. Teixeira

    2009-06-01

    Full Text Available Objetivou-se com este trabalho avaliar a capacidade competitiva de genótipos de feijão de diferentes tipos de crescimento sob presença e ausência de comunidade infestante de plantas daninhas, em duas safras de cultivo ("águas'' de 2006/07 e "seca'' de 2007. Foi utilizado o delineamento de blocos casualizados, em esquema fatorial 3 x 2, com quatro repetições. Os tratamentos foram constituídos de três cultivares de feijão com diferentes tipos de crescimento (Pérola: tipo III/II; Aporé: tipo III; e BRS Radiante: tipo I, em combinação com dois tipos de manejo de plantas daninhas: área capinada manualmente e área não capinada. Conclui-se que no cerrado brasileiro, na safra das "águas'', os problemas da cultura do feijão com as plantas daninhas foram agravados, especialmente com Brachiaria ssp., Cenchrus echinatus, Digitaria horizontalis e Eleusine indica. Os cultivares de feijão com hábitos de crescimento semiereto (Pérola e prostrado (Aporé foram mais competitivos com a comunidade infestante de plantas daninhas.This work aimed to evaluate the competitive capacity of common bean cultivars of different growth types under the presence and absence of weed species communities during two crop seasons(rainy 2006/2007 and dry 2007. The experiment was arranged in a randomized block design, in a factorial scheme with four replications. The treatments consisted of three bean cultivars with different types of growth ("Pérola'': type III/II, "Aporé'': type III and "BRS Radiante'': type I in combination with two types of management of weed species: cultivated with and without weed. It was concluded that in the "cerrado'' during the rainy season, the problems of the common bean with the weed species aggravated, especially in relation to Brachiaria ssp., Cenchrus echinatus, Digitaria horizontalis and Eleusine indica. The common bean genotypes with semi-erect ("Pérola'' and prostrated ("Aporé' growth habits were more competitive against

  16. Valor nutritivo da forragem e produção animal em pastagens de Brachiaria brizantha Forage nutritive value and animal production in Brachiaria brizantha pastures

    Directory of Open Access Journals (Sweden)

    Valéria Pacheco Batista Euclides

    2009-01-01

    Full Text Available O objetivo deste trabalho foi avaliar a produção animal e sua relação com as características dos pastos de Brachiaria brizantha cultivares Marandu, Xaraés e Piatã. O delineamento experimental foi o de blocos ao acaso, com três tratamentos e duas repetições. Os piquetes com 2 ha foram subdivididos em dois e submetidos ao pastejo alternado, com 28 dias de utilização e 28 dias de descanso. Foram utilizados três novilhos teste, por piquete, e novilhos reguladores para manter resíduos pós pastejo em torno de 3 Mg ha-1 de matéria seca. Mensalmente, os pastos foram avaliados para se estimar o valor nutritivo da forragem. Os animais foram pesados, e as taxas de lotação foram ajustadas duas vezes por semana. No pasto da cv. Xaraés, apesar do menor ganho médio diário (GMD dos animais, a taxa de lotação foi maior, o que resultou em maior produtividade da cv. Xaraés, em comparação às cvs. Marandu e Piatã. No pasto da cv. Piatã, houve aumento do GMD, o que indica que as cvs. Xaraés e Piatã são novas alternativas para a diversificação dos pastos no Cerrado. Assim, a escolha da forragem deve se dar em razão da meta do sistema de produção, ou seja, a produção por animal ou por área.The objectives of this work were to evaluate animal production and its relationship with pasture characteristics of Brachiaria brizantha cultivars Marandu, Xaraés and Piatã. The experiment had a randomized complete block design, with three treatments and two replicates. Two-ha paddocks were divided into two and submitted to alternated grazing, with 28 days of grazing and 28 days of rest. Three tester steers were kept in each paddock; additional steers were placed in each paddock by the put and take technique, to assure post grazing residues of about 3 Mg ha-1 of dry matter. The pastures were sampled monthly to estimate the nutritive value of the forage. The animals were weighted, and the stocking rate was adjusted twice a week. Despite the

  17. Progresso e controle da mela-das-sementes (Claviceps maximensis de Brachiaria brizantha Progress and control of honeydew (Claviceps maximensis of Brachiaria brizantha

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Marchi

    2008-09-01

    Full Text Available Verificou-se a eficiência de uma ou duas aplicações de Piraclostrobin + Epoxiconazole, Mancozeb, Triadimenol, Azoxistrobin + Ciproconazole, Trifloxistrobin + Ciproconazole ou Tebuconazole no controle da mela-das-sementes de Brachiaria brizantha cvs. Marandu e Xaraés, durante a safra 2004-05. Também foram avaliados os indutores de resistência Acibenzolar-S-Metil e Silicato de Potássio (via aérea ou solo. Triadimenol, com uma ou duas aplicações, Piraclostrobin + Epoxiconazole, Azoxistrobin + Ciproconazole, Trifloxistrobin + Ciproconazole ou Tebuconazole, com duas aplicações, foram promissores no controle da mela-das-sementes do capim-marandu. Já para a cv. Xaraés, melhor controle foi alcançado com o Piraclostrobin + Epoxiconazole, independente do número de aplicações, Triadimenol, Trifloxistrobin + Ciproconazole ou Tebuconazole, com duas aplicações. Não houve correlação entre os dados de produção de sementes puras e a intensidade da mela. Com relação ao progresso da mela-das-sementes de B. brizantha cvs. Marandu e Xaraés, constatou-se que a doença manifestou-se em períodos frios associados à umidade relativa alta. Na cv. Marandu a doença ocorreu na fase final da cultura, enquanto que na cv. Xaraés, a mela foi detectada na fase de intenso florescimento. Foram constatados aumentos na intensidade da doença em ambas as cultivares. A mela-das-sementes ocorreu em 64% das panículas da cv. Marandu e em 81% das panículas da cv. Xaraés; cerca de 20% e 18% das flores/sementes, respectivamente, foram afetadas. Os resultados demonstraram existir correlação positiva entre os valores de incidência e severidade da mela.The efficiency of one or two applications of Pyraclostrobin + Epoxyconazole, Mancozeb, Triadimenol, Azoxystrobin + Cyproconazole, Trifloxystrobin + Cyproconazole or Tebuconazole in the control of honeydew in seeds of Brachiaria brizantha cvs. Marandu and Xaraes was verified during crop 2004-05. The inductors

  18. An ultrasonic system for weed detection in cereal crops.

    Science.gov (United States)

    Andújar, Dionisio; Weis, Martin; Gerhards, Roland

    2012-12-13

    Site-specific weed management requires sensing of the actual weed infestation levels in agricultural fields to adapt the management accordingly. However, sophisticated sensor systems are not yet in wider practical use, since they are not easily available for the farmers and their handling as well as the management practice requires additional efforts. A new sensor-based weed detection method is presented in this paper and its applicability to cereal crops is evaluated. An ultrasonic distance sensor for the determination of plant heights was used for weed detection. It was hypothesised that the weed infested zones have a higher amount of biomass than non-infested areas and that this can be determined by plant height measurements. Ultrasonic distance measurements were taken in a winter wheat field infested by grass weeds and broad-leaved weeds. A total of 80 and 40 circular-shaped samples of different weed densities and compositions were assessed at two different dates. The sensor was pointed directly to the ground for height determination. In the following, weeds were counted and then removed from the sample locations. Grass weeds and broad-leaved weeds were separately removed. Differences between weed infested and weed-free measurements were determined. Dry-matter of weeds and crop was assessed and evaluated together with the sensor measurements. RGB images were taken prior and after weed removal to determine the coverage percentages of weeds and crop per sampling point. Image processing steps included EGI (excess green index) computation and thresholding to separate plants and background. The relationship between ultrasonic readings and the corresponding coverage of the crop and weeds were assessed using multiple regression analysis. Results revealed a height difference between infested and non-infested sample locations. Density and biomass of weeds present in the sample influenced the ultrasonic readings. The possibilities of weed group discrimination were

  19. Nitrogen loss in Brachiaria decumbens after application of glyphosate or glufosinate-ammonium Perdas de nitrogênio por Brachiaria decumbens após a aplicação de glifosato ou glufosinato de amônio

    Directory of Open Access Journals (Sweden)

    Virginia Damin

    2008-01-01

    Full Text Available Nitrogen losses from the soil-plant system may be influenced by herbicide applications. In order to evaluate N loss in brachiaria (Brachiaria decumbens after application of the herbicides glyphosate and glufosinate-ammonium, an experiment was carried out in a greenhouse as a completely randomized design, with three treatments and six replicates. Treatments were as follows: i desiccation of brachiaria-plants with glyphosate; ii desiccation of brachiaria-plants with glufosinate-ammonium; and iii control, without herbicide application. The plants were cultivated in 4 kg pots of sandy soil and fertilized with ammonium sulfate- 15N, (200 mg kg-1 in order to quantify the allocation of the fertilizer-N and its recovery in the soil-plant system. Plants treated with the herbicides had less N accumulation and less recovery of the fertilizer-N (15N relative to the control. In the soil, the greatest recovery of 15N-fertilizer occurred for treatments where N was applied, possibly due to the occurrence of other N compound losses to the soil, like root exudation and root death. The total recovery of 15N-fertilizer in the soil-plant system was higher in the control than in the treated plants showing the direct action of the herbicides on nitrogen loss, and especially by the above-ground part of the brachiaria plants.As perdas de nitrogênio no sistema solo-planta podem ser influenciadas pela aplicação de herbicidas. Com o objetivo de avaliar a perda de N do capim-Brachiaria (Brachiaria decumbens após a aplicação dos herbicidas glifosato e glufosinato de amônio, foi realizado um experimento em casa-de-vegetação em delineamento inteiramente aleatorizado (DIA, com três tratamentos e seis repetições. Os tratamentos foram os seguintes: i dessecação de plantas de braquiária com o herbicida glifosato; ii dessecação de plantas de braquiária com herbicida glufosinato de amônio e iii testemunha, sem aplicação de herbicida. As plantas foram cultivadas

  20. Rooting strategies of Brachiaria genotypes in acid and low fertility soils of Colombia Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia

    Directory of Open Access Journals (Sweden)

    Menjivar Juan Carlos

    2007-09-01

    Full Text Available In a Typic Haplustox soil in the “Altillanura” of the Eastern Plains (Llanos Orientales of Colombia Shoot biomass production was evaluated, during 41 months in 6 Brachiaria genotypes with variable resistance to high Al levels. with two nutrient levels. Moderate and highly Al-resistant Brachiaria genotypes maintained high shoot biomass production in early months of establishment, declined to medium values until 21 months. Root biomass and root length production of Brachiaria genotypes, as well as native savanna grasses, was greater during rainy season, with a high root production in the first 5 cm of the soil. Savanna species and the genotypes B. decumbens CIAT 606 (high Al+3 resistant produced finer roots and less root biomass than native savanna species. The dry season induced a proportional increase in deeper root length and biomass production compared with rainy season in both moderately and highly Al-resistant Brachiaria genotypes as well as in native savanna species.En un Haplustox de los Llanos Orientales de Colombia se evaluaron durante 41 meses 6 genotipos de Brachiaria con resistencia variable a niveles altos de Al+3 en dos niveles de nutrientes. Los genotipos con resistencia media y alta mantuvieron altas producciones de biomasa aérea en los primeros meses, decrecieron a valores medios y estables hacia los 21 meses. La producción de biomasa y longitud de raíces en los genotipos de Brachiaria y especies de sabana nativa fue mayor en época lluviosa, con alta producción en los primeros 5 cm del perfil de suelo. Las gramíneas de la sabana nativa y B. decumbens CIAT 606 (altamente resistente a Al+3 generaron raíces finas y menor biomasa de raíces. Durante la época seca los genotipos de Brachiaria

  1. Guidelines for management of noxious weeds at Hanford

    International Nuclear Information System (INIS)

    Roos, R.C.; Malady, M.B.

    1995-01-01

    Integrated Pest Management Services is responsible for management and control of noxious weeds on the Hanford Site. Weed species and populations are prioritized and objective defined, according to potential site and regional impact. Population controls are implemented according to priority. An integrated approach is planned for noxious weed control in which several management options are considered and implemented separately or in coordination to best meet management objectives. Noxious weeds are inventories and monitored to provide information for planning and program review

  2. Weed Control in Clean Agriculture: A Review1

    OpenAIRE

    ABOUZIENA,H.F.; HAGGAG,W.M.

    2016-01-01

    ABSTRACT Weed control is consider the major obstacle for the growers in the organic farming. Lower plant productivity in organic farming mainly related to the poor weed control. It is widely known, in most cases, that losses caused by weeds exceeded the losses from any category of agricultural pests. Under water-stress condition, weeds can reduce crop yields more than 50% through moisture competition alone. In the light of the environmental and toxicological problems created by herbicides, it...

  3. Tolerância do Tifton 85 (Cynodon spp. e da Brachiaria brizantha ao glyphosate Tifton 85 (Cynodon spp. and Brachiaria brizantha tolerance to glyphosate

    Directory of Open Access Journals (Sweden)

    M.V. Santos

    2008-06-01

    Full Text Available Objetivou-se avaliar a tolerância de Tifton 85 e Brachiaria brizantha ao glyphosate e verificar o controle de B. brizantha em área de pastagem de Tifton 85 já estabelecida. O delineamento experimental foi em blocos casualizados, com quatro repetições, em que se testaram as doses: 0, 720, 1.440, 2.160 e 2.880 g ha-1 de glyphosate. Cada parcela possuía dimensões de 3,5 m de comprimento por 3,0 m de largura, totalizando 10,5 m², com área útil de 7,5 m ². A eficiência do herbicida no controle de B. brizantha e o nível de intoxicação nas plantas de Tifton 85 foram avaliados 15, 30 e 60 dias após aplicação (DAA, mediante escala de 0 a 100, em que 0 é ausência de controle e/ou intoxicação e 100, controle total ou morte das plantas. Para avaliação da produção e do potencial de rebrota das forrageiras, as plantas de ambas as espécies foram colhidas aos 300 DAA e secas em estufa. Observou-se controle acima de 90% das plantas de B. brizantha a partir das doses de 1.473,75 e 1.721,25 g ha-1 de glyphosate, aos 30 e 60 DAA, respectivamente. As porcentagens de intoxicação das plantas de Tifton 85, referente a estas doses de controle de B. brizantha, foram, respectivamente, de 24,90 e 4,13% aos 30 e 60 DAA. Além disso, aos 60 DAA, para a maior dose avaliada (2.880 g ha-1 de glyphosate foi observada intoxicação das plantas de Tifton 85 de apenas 18,22%. Aos 300 DAA, observou-se ausência de produção de massa seca de B. brizantha a partir da dose de 2.160 g ha-1 do herbicida, devido ao eficiente controle. Os resultados evidenciam maior tolerância das plantas de Tifton 85 ao glyphosate em relação às plantas de B. brizantha, possibilitando o controle desta espécie em pastagem estabelecida de Tifton 85, sem causar danos à forrageira cultivada.This study aimed to evaluate Tifton 85 and Brachiaria brizantha tolerance glyphosate and verity Brachiaria brizantha control in an established Tifton 85 pasture area. Rates of 0; 720; 1

  4. CALCIUM SOURCE EFFECT ON APPARENT DIGESTIBILITY OF GRASS HAY Brachiaria decumbens Staph cv. Basiliski EFEITO DA FONTE DE CÁLCIO (calcário vs Lithothamnium calcareum) NA DIGESTIBILIDADE APARENTE DE CAPIM Brachiaria decumbens Staph cv. Basiliski

    OpenAIRE

    Deborah Gonçalves Rodrigues; Clizeide R. Oliveira; Benir de Oliveira; Celso de Paula Costa; Geisa Fleury Orsine

    2007-01-01

    An experiment was developed to determine the effect of addition of the marine alga Lithothamnium calcareum in the apparent digestibility of a low quality forage. Twelve adult lambs were kept in metabolical individual cages using a randomly design with three replications and four treatments as follows: I - Brachiaria decumbens grass hay, processed after the seed harvest; II - Hay plus 1000 ppm of calcium from CaCO3 ...

  5. Controlling grass weeds on hard surfaces

    DEFF Research Database (Denmark)

    Rask, Anne Merete; Kristoffersen, Palle; Andreasen, Christian

    2012-01-01

    An experiment was conducted on a specially designed hard surface to study the impact of time interval between flaming treatments on the regrowth and flower production of two grass weeds. The goal of this experiment was to optimize the control of annual bluegrass and perennial ryegrass, both species...... that are very difficult to control without herbicides. Aboveground biomass from 72 plants per treatment was harvested and dry weights were recorded at regular intervals to investigate how the plants responded to flaming. Regrowth of the grasses was measured by harvesting aboveground biomass 2 wk after......, as they did not increase the reduction of aboveground biomass compared with the 7-d treatment interval. Knowledge on the regrowth of grass weeds after flaming treatments provided by this study can help improve recommendations given to road keepers and park managers for management on these weeds. Nomenclature...

  6. Weeded Out? Gendered Responses to Failing Calculus.

    Science.gov (United States)

    Sanabria, Tanya; Penner, Andrew

    2017-06-01

    Although women graduate from college at higher rates than men, they remain underrepresented in science, technology, engineering, and mathematics (STEM) fields. This study examines whether women react to failing a STEM weed-out course by switching to a non-STEM major and graduating with a bachelor's degree in a non-STEM field. While competitive courses designed to weed out potential STEM majors are often invoked in discussions around why students exit the STEM pipeline, relatively little is known about how women and men react to failing these courses. We use detailed individual-level data from the National Educational Longitudinal Study (NELS) Postsecondary Transcript Study (PETS): 1988-2000 to show that women who failed an introductory calculus course are substantially less likely to earn a bachelor's degree in STEM. In doing so, we provide evidence that weed-out course failure might help us to better understand why women are less likely to earn degrees.

  7. Pest Control in Corn and Soybeans: Weeds - Insects - Diseases.

    Science.gov (United States)

    Doersch, R. E.; And Others

    This document gives the characteristics and application rates for herbicides used to control annual weeds in corn, annual and perennial broadleaf weeds in corn, quackgrass and yellow nutsedge in corn, and annual weeds in soybeans. It also gives insecticide use information for corn and soybeans. A brief discussion of disease control in corn and…

  8. Conservation implications of weed management of lake reservoirs ...

    African Journals Online (AJOL)

    Management of weeds around lake reservoirs is often implemented to reduce any possibility of siltation. However, machineries used in weed management have resulted in habitat degradation and geometrical multiplication of weeds by chopping rhizomes and scattering seeds. In general, the removal offers some feedbacks ...

  9. Descriptive and mechanistic models of crop–weed competition

    NARCIS (Netherlands)

    Bastiaans, L.; Storkey, J.

    2017-01-01

    Crop-weed competitive relations are an important element of agroecosystems. Quantifying and understanding them helps to design appropriate weed management at operational, tactical and strategic level. This chapter presents and discusses simple descriptive and more mechanistic models for crop-weed

  10. Effect of the Critical Period of Weed Interference on Optimum ...

    African Journals Online (AJOL)

    A field study was carried out at the National Root Crop Research Institute experimental farm to determine the critical period of weed interference and magnitude of yield loss caused by weed on turmeric in 2008 and 2009 cropping season. Turmeric was subjected to 13 weeding regimes using randomized complete block ...

  11. Focus on ecological weed management : what is hindering adoption?

    NARCIS (Netherlands)

    Bastiaans, L.; Paolini, R.; Baumann, D.T.

    2008-01-01

    Despite increased concerns regarding the heavy reliance of many cropping systems on chemical weed control, adoption of ecological weed management practices is only steadily progressing. For this reason, this paper reflects on both the possibilities and limitations of cultural weed control practices.

  12. Image-based thresholds for weeds in maize fields

    DEFF Research Database (Denmark)

    Asif, Ali; Streibig, Jens Carl; Christensen, Svend

    2015-01-01

    in some parts of the field and if late germinating weeds do not affect yield, it may not be necessary the spray such places from an economic point of view. Consequently, it makes sense to develop weed control thresholds for patch spraying, based on weed cover early in the growing season. In Danish maize...

  13. Evaluation of UAV imagery for mapping Silybum marianum weed patches

    Science.gov (United States)

    The invasive weed, milk thistle (Silybum marianum), has the tendency to grow in patches. In order to perform site-specific weed management, determining the spatial distribution of weeds is important for its eradication. Remote sensing has been used to perform species discrimination, and it offers pr...

  14. Onion and weed response to mustard (Sinapis alba) seed meal

    Science.gov (United States)

    Weed control in organic onion production is often difficult and expensive, requiring numerous cultivations and extensive hand-weeding. Onion safety and weed control with mustard seed meal (MSM) derived from Sinapis alba was evaluated in greenhouse and field trials. MSM applied at 110, 220, and 440 g...

  15. Cover crop-based ecological weed management: exploration and optimization

    NARCIS (Netherlands)

    Kruidhof, H.M.

    2008-01-01

    Keywords: organic farming, ecologically-based weed management, cover crops, green manure, allelopathy, Secale cereale, Brassica napus, Medicago sativa

    Cover crop-based ecological weed management: exploration and optimization. In organic farming systems, weed control is recognized as one

  16. A century of progress in weed control in hardwood seedbeds

    Science.gov (United States)

    David B. South

    2009-01-01

    Weeds have existed in nurseries since before the time Bartram grew hardwoods during the 18th century. Hand weeding was the primary method of weed control during the first part of the 20th century. From 1931 to 1970, advances in chemistry increased the use of herbicides, and advances in engineering increased the reliance on machines for cultivation. Many managers now...

  17. Mechanical weed control in organic winter wheat

    OpenAIRE

    Euro Pannacci; Francesco Tei; Marcello Guiducci

    2017-01-01

    Three field experiments were carried out in organic winter wheat in three consecutive years (exp. 1, 2005-06; exp. 2, 2006- 07; exp. 3, 2007-08) in central Italy (42°57’ N - 12°22’ E, 165 m a.s.l.) in order to evaluate the efficacy against weeds and the effects on winter wheat of two main mechanical weed control strategies: i) spring tine harrowing used at three different application times (1 passage at T1, 2 passages at the time T1, 1 passage at T1 followed by 1 passage at T1 + 14 days) in t...

  18. Population dynamics of weeds in oil palm (Elaeis guineensis Jacq.) circle weeding area affected by herbicide application

    Science.gov (United States)

    Sidik, S.; Purba, E.; Yakub, E. N.

    2018-02-01

    Weed problems in oil palm field were mainly overcomed by herbicide application. The application certain herbicides may lead to rapid population dynamic of certain species due to their different response to herbicides. Some species may less susceptible to certain herbicide whereas other species more susceptible. The objective of this study was to determine the population dynamic of weed species in circle weeding of oil palm in Serdang Bedagai, North Sumatra. Six treatments using glyphosate singly and mixture compared with manual weeding were evaluated for weed control. The treatments were arranged in a randomized block design with four replicates. Each treatment consisted of four circle weedings. The results showed that glyphosate 720 g a.i/ha + indaziflam 50 g a.i/hareduced seedbank and regrowth of weeds. Up to 12 weeks after application glyphosate 720 g a.i/ha + indaziflam 50 g a.i/ha is 29.46% total weeds dry weight compared to manual weeding. The effect of herbicide application on changes on the weed composition and weed seedbank are affected by the characteristic of herbicides and weed response to herbicide application.

  19. Virus infection of a weed increases vector attraction to and vector fitness on the weed.

    Science.gov (United States)

    Chen, Gong; Pan, Huipeng; Xie, Wen; Wang, Shaoli; Wu, Qingjun; Fang, Yong; Shi, Xiaobin; Zhang, Youjun

    2013-01-01

    Weeds are important in the ecology of field crops, and when crops are harvested, weeds often become the main hosts for plant viruses and their insect vectors. Few studies, however, have examined the relationships between plant viruses, vectors, and weeds. Here, we investigated how infection of the weed Datura stramonium L. by tomato yellow leaf curl virus (TYLCV) affects the host preference and performance of the TYLCV vector, Bemisia tabaci (Gennadius) Q. The results of a choice experiment indicated that B. tabaci Q preferentially settled and oviposited on TYLCV-infected plants rather than on healthy plants. In addition, B. tabaci Q performed better on TYLCV-infected plants than on healthy plants. These results demonstrate that TYLCV is indirectly mutualistic to B. tabaci Q. The mutually beneficial interaction between TYLCV and B. tabaci Q may help explain the concurrent outbreaks of TYLCV and B. tabaci Q in China.

  20. BIOLOGICAL CONTROL OF WEEDS BY MEANS OF PLANT PATHOGENS

    Directory of Open Access Journals (Sweden)

    Marija Ravlić

    2014-06-01

    Full Text Available Biological control is the use of live beneficial organisms and products of their metabolism in the pests control. Plant pathogens can be used for weed control in three different ways: as classical, conservation and augmentative (inoculative and inundated biological control. Inundated biological control involves the use of bioherbicides (mycoherbicides or artificial breeding of pathogens and application in specific stages of crops and weeds. Biological control of weeds can be used where chemical herbicides are not allowed, if resistant weed species are present or in the integrated pest management against weeds with reduced herbicides doses and other non-chemical measures, but it has certain limitations and disadvantages.

  1. Non-targeted Colonization by the Endomycorrhizal Fungus, Serendipita vermifera, in Three Weeds Typically Co-occurring with Switchgrass

    Directory of Open Access Journals (Sweden)

    Prasun Ray

    2018-01-01

    Full Text Available Serendipita vermifera (=Sebacina vermifera; isolate MAFF305830 is a mycorrhizal fungus originally isolated from the roots of an Australian orchid that we have previously shown to be beneficial in enhancing biomass yield and drought tolerance in switchgrass, an important bioenergy crop for cellulosic ethanol production in the United States. However, almost nothing is known about how this root-associated fungus proliferates and grows through the soil matrix. Such information is critical to evaluate the possibility of non-target effects, such as unintended spread to weedy plants growing near a colonized switchgrass plant in a field environment. A microcosm experiment was conducted to study movement of vegetative mycelia of S. vermifera between intentionally inoculated switchgrass (Panicum virgatum L. and nearby weeds. We constructed size-exclusion microcosms to test three different common weeds, large crabgrass (Digitaria sanguinalis L., Texas panicum (Panicum texanum L., and Broadleaf signalgrass (Brachiaria platyphylla L., all species that typically co-occur in Southern Oklahoma and potentially compete with switchgrass. We report that such colonization of non-target plants by S. vermifera can indeed occur, seemingly via co-mingled root systems. As a consequence of colonization, significant enhancement of growth was noted in signalgrass, while a mild increase (albeit not significant was evident in crabgrass. Migration of the fungus seems unlikely in root-free bulk soil, as we failed to see transmission when the roots were kept separate. This research is the first documentation of non-targeted colonization of this unique root symbiotic fungus and highlights the need for such assessments prior to deployment of biological organisms in the field.

  2. Silicon accumulation and water deficit tolerance in Brachiaria grasses Acúmulo de silício e tolerância ao déficit hídrico em capins do gênero Brachiaria

    Directory of Open Access Journals (Sweden)

    Suzana Pereira de Melo

    2003-12-01

    Full Text Available The beneficial effects of silicon (Si fertilization have been observed for several plant species, especially when submitted to stress, either biotic or abiotic. Among the possible reasons for the greater adaptability and resistance of brachiaria grass in areas of low fertility soils in Brazilian savanna, stands its capacity of absorbing and accumulating Si in aerial parts. To evaluate the effect of Si on dry matter yield of Brachiaria decumbens Stapf and Brachiaria brizantha Hochst, grown under two soil moisture regimes, a trial was set up in a completely randomized design factorial scheme (5 × 2 × 2, with five Si rates: (0; 242; 484; 968 and 1,452 kg ha-1, two soil water tensions (60% and 80% of field capacity and the two brachiaria species. The experiment was installed in a greenhouse, using one of the most representative soils in the region under cerrado, Typic Haplustox. Both brachiaria species can be considered Si-accumulating plants, since they present high Si contents in their aerial parts. Application of Si to the soil increased the contents of this element in both grass species but did not change their tolerance to water deficit, and did not affect dry matter yield.Efeitos benéficos da adubação com silício (Si têm sido observados em várias espécies vegetais, especialmente quando estas estão submetidas a estresse biótico ou abiótico. Entre as possíveis razões para a maior adaptabilidade e resistência do capim braquiária nas áreas de baixa fertilidade do solo das regiões do cerrado brasileiro, esta associada à sua capacidade em absorver e acumular Si na parte aérea. Este trabalho teve como objetivo avaliar o efeito da aplicação de Si sobre a produção de matéria seca de duas espécies das gramíneas Brachiaria decumbens Stapf e Brachiaria brizantha Hochst, cultivadas sob dois regimes de umidade no solo. Os ensaios foram instalados em delineamento inteiramente casualizado, em esquema fatorial (5 × 2 × 2 com cinco

  3. Weed infestation of spring barley (Hordeum vulgare L. depending on the cover crop and weed control method

    Directory of Open Access Journals (Sweden)

    Dorota Gawęda

    2014-04-01

    Full Text Available The aim of this 3-year field study was to evaluate the effect of some stubble crops and weed control methods on the species composition, number and air-dry weight of weeds in a spring barley crop grown in short-term monoculture. The study was conducted in the period 2009–2011 at the Uhrusk Experimental Farm, on mixed rendzina soil classified as very good rye soil complex. It included stubble crops which were ploughed under in each year (control treatment without cover crop, white mustard, lacy phacelia, a mixture of legumes – narrow-leaf lupin + field pea and 3 weed control methods used in spring barley crops (mechanical, mechanical and chemical, chemical weed control. Veronica persica was the weed species that occurred in greatest numbers in the spring barley crop sown after stubble crops. All cover crops reduced the numbers of Avena fatua which was the dominant species in the control treatment. Chemical as well as chemical and mechanical weed control significantly reduced the numbers of Avena fatua compared to the treatment where only double harrowing was used for weed control. The stubble crops did not reduce weed infestation of spring barley. Compared to the control treatment, the ploughing-in of white mustard and the mixture of legumes reduced the dry weight of weeds by 49.1 and 22.7%, respectively. Mechanical weed management proved to be less effective in reducing the number and dry weight of weeds compared to the other weed control methods. A significant negative correlation was found between the dry weight of weeds in the spring barley crop and the dry weight of the ploughed-in white mustard cover crop under the conditions of chemical weed control as well as in the case of the mixture of legumes when complete mechanical and chemical weed control was used.

  4. Weed hosts of cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae).

    Science.gov (United States)

    Vennila, S; Prasad, Y G; Prabhakar, M; Agarwal, Meenu; Sreedevi, G; Bambawale, O M

    2013-03-01

    The exotic cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) invaded India during 2006, and caused widespread infestation across all nine cotton growing states. P. solenopsis also infested weeds that aided its faster spread and increased severity across cotton fields. Two year survey carried out to document host plants of P. solenopsis between 2008 and 2010 revealed 27, 83, 59 and 108 weeds belonging to 8, 18, 10 and 32 families serving as alternate hosts at North, Central, South and All India cotton growing zones, respectively. Plant species of four families viz., Asteraceae, Amaranthaceae, Malvaceae and Lamiaceae constituted almost 50% of the weed hosts. While 39 weed species supported P. solenopsis multiplication during the cotton season, 37 were hosts during off season. Higher number of weeds as off season hosts (17) outnumbering cotton season (13) at Central over other zones indicated the strong carryover of the pest aided by weeds between two cotton seasons. Six, two and seven weed hosts had the extreme severity of Grade 4 during cotton, off and cotton + off seasons, respectively. Higher number of weed hosts of P. solenopsis were located at roadside: South (12) > Central (8) > North (3) zones. Commonality of weed hosts was higher between C+S zones, while no weed host was common between N+S zones. Paper furnishes the wide range of weed hosts of P. solenopsis, discusses their significance, and formulated general and specific cultural management strategies for nationwide implementation to prevent its outbreaks.

  5. Parthenium weed ( Parthenium hysterophorus L.) research in ...

    African Journals Online (AJOL)

    Parthenium is an exotic invasive weed that now occurs widely in Ethiopia. Surveys to determine the presence and distribution of pathogens associated with parthenium and further evaluation of the pathogens found as potential biocontrol agents were carried out in Ethiopia since 1998. Several fungal isolates of the genus ...

  6. Weed identification using an automated active shape matching (AASM) technique

    DEFF Research Database (Denmark)

    C. Swain, Kishore; Nørremark, Michael; Jørgensen, Rasmus Nyholm

    2011-01-01

    Weed identification and control is a challenge for intercultural operations in agriculture. As an alternative to chemical pest control, a smart weed identification technique followed by mechanical weed control system could be developed. The proposed smart identification technique works on the con......Weed identification and control is a challenge for intercultural operations in agriculture. As an alternative to chemical pest control, a smart weed identification technique followed by mechanical weed control system could be developed. The proposed smart identification technique works...... on the concept of ‘active shape modelling’ to identify weed and crop plants based on their morphology. The automated active shape matching system (AASM) technique consisted of, i) a Pixelink camera ii) an LTI (Lehrstuhlfuer technische informatik) image processing library, iii) a laptop pc with the Linux OS. A 2...

  7. Weeds optimally grow in peat swamp after burning

    Directory of Open Access Journals (Sweden)

    P.D. Susanti

    2014-07-01

    Full Text Available After clearing land by burning the peat, then the weeds and undergrowth will flourish. Even sometimes, the weeds are eventually burned again. Weed is known as a destroyer plant that has to be controlled. Through proper treatment, the existing weeds in peatlands can be potentiallly exploited. The purpose of this study was to determine the calorific value of briquettes as one of peatland weeds utilization. The results showed that the calorific value ranged from 2,492 cal/g to 5,230 cal/g. The lowest calorific value was on ‘teki kecil’ grass (Scirpus grossus Lf, while the highest calorific value was observed for ‘bantalaki grass’ (Hymenachne amplexicaulis Nees. The high calorific value of the peat weeds are potential for biomass briquettes raw materials. The utilization and use of peat weed briquettes as a raw materials expected can reduce land degradation due to peat swamp burning

  8. Avaliação de herbicidas de pós-emergência na cultura da cebola Evaluation of herbicides on post emergent weed control in onion crop

    Directory of Open Access Journals (Sweden)

    Jeferson Zagonel

    2000-11-01

    Full Text Available O objetivo deste trabalho foi avaliar a eficiência e a seletividade do herbicida clethodim, em duas formulações (120 e 240 g/l, no controle de plantas daninhas na cultura da cebola. O experimento foi instalado na Fazenda Escola da UEPG, em Ponta Grossa (PR, no ano de 1998. O delineamento experimental utilizado foi blocos ao acaso com quatro repetições, constando dos tratamentos: clethodim (120 g/l + óleo mineral nas doses de 72, 84 e 96 g i.a./ha; clethodim (240 g/l na dose de 84 g i.a./ha adicionado de 1,0 l/ha de óleo mineral (Assist; testemunha capinada e testemunha sem capina. A cultivar de cebola utilizada foi Baia Periforme e as plantas daninhas predominantes no experimento foram Brachiaria plantaginea (capim-papuã, Digitaria horizontalis (capim-milhã e Eleusine indica (capim pé-de-galinha. As avaliações de controle e de fitotoxicidade foram efetuadas aos 7, 14, 28 e 42 dias após a aplicação dos tratamentos (DAA onde verificou-se que o clethodim (120 g/l nas doses de 84 e 96 g i.a./ha foi igualmente eficiente ao clethodim (240 g/l no controle sobre Brachiaria plantaginea, Digitaria horizontalis e Eleusine indica; esses tratamentos mostraram produção similar e superior à verificada para a testemunha sem capina e causaram leve redução no porte das plantas de cebola aos 7 dias após sua aplicação, o que não foi mais observado nas avaliações posteriores.This study had the purpose of evaluating the efficiency and selectivity of the herbicide clethodim, in two formulations (120 and 240 g/l for weed control in onion crop. The experiment was realized at the University of Ponta Grossa, in Brazil, in 1998. The experimental design was of randomized blocks with four replicates. The following treatments were evaluated: clethodim (120 g/L + mineral oil using doses of 72, 84 and 96 g i.a./ha; clethodim (240 g/L with 84 g i.a./ha added with 1.0 L/ha of mineral oil; weed free and weedy. The onion cultivar used was Baia Periforme

  9. Eficácia de herbicidas inibidores da ACCase no controle de gramíneas em lavouras de soja Efficacy of ACCase-inhibiting herbicides in controlling grass weeds in soybean crops

    Directory of Open Access Journals (Sweden)

    A.L.L. Barroso

    2010-01-01

    Full Text Available Objetivou-se com este trabalho avaliar a eficácia de herbicidas inibidores da ACCase, aplicados isoladamente ou em associações, no controle das espécies de plantas daninhas pertencentes à família das gramíneas Brachiaria decumbens, Digitaria ciliaris, Eleusine indica, Brachiaria plantaginea e Cenchrus echinatus, na cultura da soja. O experimento foi conduzido em campo, em delineamento de blocos ao acaso com quatro repetições. Os tratamentos avaliados foram: clethodim (84 g ha-1, clethodim + quizalofop-p-ethyl (48 + 40 g ha-1, [clethodim + fenoxaprop-p-ethyl] (50 + 50 g ha-1, sethoxydim (230 g ha-1, tepraloxydim (100 g ha-1, fluazifop-p-butyl (125 g ha-1, haloxyfop-methyl (60 g ha-1 e testemunha sem herbicida. A convivência das plantas de soja com as gramíneas infestantes resultou em perda significativa na produtividade de grãos. Os melhores níveis de controle de B. decumbens foram verificados com a utilização de haloxyfop-methyl. Tepraloxydim pode ser considerado seletivo a B. decumbens. Nenhum tratamento proporcionou controle final de D. ciliaris superior a 90%, porém menor eficiência foi verificada quando se aplicaram sethoxydim e fluazifop-p-butyl. Apenas os tratamentos sethoxydim e [clethodim + fenoxaprop-p-ethyl] não mostraram controle satisfatório de E. indica. B. plantaginea foi a espécie mais facilmente controlada pelos herbicidas avaliados; no entanto, haloxyfop-methyl, tepraloxydim, clethodim e [clethodim + fenoxaprop-p-ethyl] se destacaram no controle dessa invasora. A adição de quizalofop-p-ethyl ao clethodim proporcionou incremento significativo no controle de C. echinatus. Também os herbicidas haloxyfop-methyl e tepraloxydim apresentaram controle satisfatório dessa espécie daninha.The objective of this work was to evaluate the efficacy of ACCase-inhibitors (ariloxyfenoxypropionates and cyclohexanodiones, applied alone or in combination, in controlling the grass weed species Brachiaria decumbens, Digitaria

  10. WEED CONTROL IN GENETICALLY MODIFIED GLYPHOSATE-TOLERANT SOYBEAN MANEJO DE PLANTAS DANINHAS EM SOJA GENETICAMENTE MODIFICADA TOLERANTE AO GLYPHOSATE

    Directory of Open Access Journals (Sweden)

    Júlio Cezar Durigan

    2011-04-01

    Full Text Available The transgenic production systems, as well as conventional systems, require, in addition to chemical control, the adoption of other weed management strategies. This study was developed to evaluate the weed chemical control in glyphosate tolerant soybean, associated to cover crops cultivated in the autumn/winter. The experiment was carried out under field conditions at the FCAV/Unesp, Jaboticabal, São Paulo State, Brazil. A randomized split-plot block design was used, with four replications. St. Lucia Grass (Brachiaria brizantha ‘Marandu’, forage millet (Pennisetum americanum ‘BN2’, and a treatment with spontaneous growth vegetation were evaluated for plots, and, for subplots, the herbicides glyphosate, chlorimuron - ethyl plus lactofen, and fluazifop-p-butyl, in a sequential spraying, and two controls without any application. Grass cover contributed to the chemical control, suppressing weeds, and the single application of 720 g a.e. ha-1 of glyphosate, independently of the cover crop cultivated in the autumn/winter, was sufficient for adequately controlling Acanthospermum hispidum, Alternanthera tenella, Amaranthus sp., Bidens pilosa, Xanthium strumarium, Cenchrus echinatus, Digitaria sp., and Eleusine indica, with results similar to the treatment (chlorimuron-ethyl + lactofen + fluazifop-p-buthyl. When compared to the weeded control, the herbicides did not affect plants height, dry matter of the aerial parts, mass of 100 grains, and grain yield. Soybean plants grown over St. Lucia Grass and forage millet presented a higher height, however, no other feature was influenced by the cover crop.

    KEY-WORDS: Brachiaria brizantha; Pennisetum americanum; no-tillage; Roundup Ready; spontaneous vegetation.

    Os sistemas de produção transgênicos, assim como os

  11. RNAseq reveals weed-induced PIF3-like as a candidate target to manipulate weed stress response in soybean.

    Science.gov (United States)

    Horvath, David P; Hansen, Stephanie A; Moriles-Miller, Janet P; Pierik, Ronald; Yan, Changhui; Clay, David E; Scheffler, Brian; Clay, Sharon A

    2015-07-01

    Weeds reduce yield in soybeans (Glycine max) through incompletely defined mechanisms. The effects of weeds on the soybean transcriptome were evaluated in field conditions during four separate growing seasons. RNASeq data were collected from six biological samples of soybeans growing with or without weeds. Weed species and the methods to maintain weed-free controls varied between years to mitigate treatment effects, and to allow detection of general soybean weed responses. Soybean plants were not visibly nutrient- or water-stressed. We identified 55 consistently downregulated genes in weedy plots. Many of the downregulated genes were heat shock genes. Fourteen genes were consistently upregulated. Several transcription factors including a PHYTOCHROME INTERACTING FACTOR 3-like gene (PIF3) were included among the upregulated genes. Gene set enrichment analysis indicated roles for increased oxidative stress and jasmonic acid signaling responses during weed stress. The relationship of this weed-induced PIF3 gene to genes involved in shade avoidance responses in Arabidopsis provide evidence that this gene may be important in the response of soybean to weeds. These results suggest that the weed-induced PIF3 gene will be a target for manipulating weed tolerance in soybean. No claim to original US government works New Phytologist © 2015 New Phytologist Trust.

  12. Changes in weed infestation of common bean (Phaseolus vulgaris L. under conditions of strip intercropping and different weed control methods

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    Aleksandra Głowacka

    2012-12-01

    Full Text Available The experiment was conducted in the years 2004-2006 in a private farm in the village of Frankamionka in Zamość district. There were two experimental factors: I. Cultivation methods - sole cropping and strip intercropping; and II. Tending methods - mechanical, mechanical-chemical, and chemical weed control. The subject of the study was weed infestation of the Mela variety of common bean. Beans were sown between 30 April and 5 May. Weed infestation was assessed in the last week before harvesting by determining its floristic composition and the frequency of occurrence of particular weed species, as well as the air-dry weight of weeds. The dominant weed species were Galinsoga parviflora, Echinochloa crus-galli, Chenopodium album, and Amaranthus retroflexus, which comprised 84.7% of the total number of weeds. Strip intercropping markedly reduced the number of weeds per unit area (by 50%, as well as the dry weight of their aerial parts. The most effective method of weed control was the mechanical-chemical method, which resulted in the lowest occurrence of weeds. It also significantly reduced the weight of weeds.

  13. Soybean in different forms of processing in the feeding of crossbred cows on brachiaria grass pastures

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    Vinícius Raimundi Andrade

    2015-02-01

    Full Text Available The objective was to evaluate intake and digestibility of nutrients, as well as milk production and composition of the milk from F1 Holstein × Gyr cows kept on pasture, supplemented with sugarcane and concentrate (28% CP. Five cows with 150±14 lactation days and average milk production of 7.1±2.1 kg/day were distributed in a 5 × 5 Latin square design. The treatments were: soybean meal-based concentrate; soy bean-based concentrate; ground soybean-based concentrate; roasted soybean-based concentrate; and ground, roasted soybean-based concentrate. Dry matter (DM, organic matter, crude protein (CP, neutral detergent fiber (NDF, total carbohydrates and total digestible nutrients intakes were not affected by the diet, but ether extract intake was higher for the animals fed soy bean-based diets than those fed soybean meal. The digestibility of DM, NDF and CP did not differ. The corrected milk yield differed between treatments; animals on the treatment with soy bean-based concentrate had the lowest production in relation to the others, which did not differ from each other. There was no difference between treatments for milk composition. Thus, soybean meal can be replaced by ground soy beans or roasted soy beans (ground or whole in diets for low-yield cows reared on Brachiaria decumbens pastures with no harm to milkproduction or composition. Therefore, the use of these alternative raw materials is recommended whenever their inclusion represents lower feeding costs.

  14. DENDROMETRY CHARACTERISTICS OF EUCALYPTUS UROPHYLLA IN SILVOPASTORAL SYSTEM UNDER DIFFERENT PLANTING SPACINGS WITH BRACHIARIA DECUMBENS

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    Raphael Pavesi Araujo

    2011-12-01

    Full Text Available The objective of this study was to evaluate the effect of spacing on eucalyptus dendrometric characteristics in silvopastoral system with Brachiaria decumbens. Three eucalyptus spacing were used (3x2, 6x4 and 10x4 m. The randomized block design was used with factorial scheme (3x4 with three densities of planting eucalyptus (3x2, 6x4 and 10x4 m and four times of evaluation (6, 12, 18 and 24 months after planting. The dendrometric characteristics were evaluated: 0,30 m diameter, diameter at breast height - 1.30 m (DBH, cup diameter, height, biomass per tree and plant survival. It was found positive effect of months of evaluation for the diameter to 0.30 m, cup diameter and height. There were no effects of spacing for the variables DBH, survival and biomass per tree when evaluated at 24 months. There was effect for biomass per hectare being 3x2 m the best treatament. It can be concluded that the planting spacing only affected the biomass per hectare, when evaluated up to 24 months of Eucalyptus urophylla grown in silvopastoral system.

  15. Change in dry matter and nutritive composition of Brachiaria humidicola grown in Ban Thon soil series

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    Jeerasak Chobtang

    2008-11-01

    Full Text Available This experiment was conducted to determine the change in dry matter and nutritive composition of Humidicola grass (Brachiaria humidicola grown in Ban Thon soil series (infertility soil as a function of growth age. One rai (0.16 ha of two-year-old pasture of fertilised Humidicola grass was uniformly cut and the regrowth samples were collected every twenty days. The samples were subjected to analysis for dry matter content and nutritive composition, i.e. crude protein, ash, calcium, phosphorus, neutral detergent fibre, acid detergent fibre, and acid detergent lignin. The results showed that while the yields of available forage and leaves increased curvilinearly (quadratic, p<0.05, the stem yield increased linearly (p<0.05 over sampling dates. The highest biomass accumulation rate was numerically observed between 40-60 days of regrowth. The concentrations of crude protein, ash, calcium and phosphorus decreased curvilinearly (quadratic, p<0.05 with advancing maturity and reached the lowest flat after 60 days of regrowth. The cell wall components, i.e. NDF, ADF and ADL, increased over the experimental period and reached the highest plateau at 40 days of regrowth. It was concluded that Humidicola grass should be grazed or preserved at the regrowth age of not over 60 days to maximise the utilisation of the grass.

  16. EFFECT OF DIESEL AND BIODIESEL ON THE GROWTH OF Brachiaria decumbens INOCULATED WITH ARBUSCULAR MYCORRHIZAL FUNGI

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    Dora Trejo

    2013-12-01

    Full Text Available Arbuscular mycorrhizal fungi have been found to be associated with plants useful in soil phytoremediation. The aim of this study was to compare the effects of diesel and biodiesel in soil and sand on the growth of Brachiaria decumbens inoculated with mycorrhizae. Two experiments were carried out: one experiment in soil and another in sand. A two-level- factorial design with three factors was used (one on sterile and another on non-sterile soil, with and without mycorrhizae; and one with diesel and another with biodiesel. In sand, a two-factor design with two levels was used (with and without mycorrhizae and with diesel and biodiesel, both with three replications. NOVADIESEL, biodiesel and PEMEX diesel were use as contaminants, both at 7%. The fresh and dry weight of the plants and percentage of mycorrhizal colonization, were assessed 30 days after planting. In soil, biodiesel was more toxic and reduced the fresh and dry weights of plants, especially in non-sterile soil. Biodiesel yielded greater mycorrhizal colonization values that doubled those of the control. In sand, diesel was found to reduce three times the fresh and dry weights of plants, compared to the biodiesel. In sand diesel presented high values of mycorrhizal colonization in comparison with biodiesel.  Plants inoculated with mycorrhizal fungi exhibited better development than non-inoculated plants, even in the presence of contaminants.

  17. Influence of limestone doses in the Manganese absorption by Brachiaria decumbens

    International Nuclear Information System (INIS)

    Armelin, Maria Jose A.; Fulas, Paulo M.M.; Saiki, Mitiko; Primavesi, Odo; Primavesi, Ana C.

    2005-01-01

    To restore a degraded pasture of Brachiaria decumbens, located in Sao Carlos - SP, Southeastern Brazil, under tropical climate, an experiment was carried out to study the influence of different methods of the limestone doses application on manganese absorption by the aboveground part of the forage, during 3 years of treatment. The experimental design was randomized block, with 6 replications and 8 treatments. The 100m 2 blocks were established in the pasture. Each block received a sequence of limestone doses (0, 1, 2, 4, and 8 t/ha) applied on soil surface with NK and, 2 t/ha applied on soil surface with plus one annual application of 1t/ha and NK, 4t/ha buried in the soil with NK, 4t/ha applied on soil surface without NK. Forages samples were collected 14 cm above soil surface. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine manganese content. The statistical analysis showed some significant variations of this element absorption by the plant with regard to the treatments, but anything that could compromise the mineral nutrition of forage. Moreover, the quality of forage for the animal feeding showed suitable agreement to manganese requirement. INAA showed that it can be an alternative option for agronomical researches that require the knowledge of the manganese concentration. (author)

  18. STRUCTURE AND NUTRITIVE VALUE OF DEFERRED PASTURE OF BRACHIARIA DECUMBENS CV. BASILISK DURING THE GRAZING PERIOD

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    Manoel Eduardo Rozalino Santos

    2011-07-01

    Full Text Available The experiment aimed to understand the effect of grazing period on morphology and nutritive value of deferred Brachiaria decumbens cv. Basilisk pasture and on hand-plucking sample with cattle. Subdivided plots were used according to a randomized block design with two replicates. Four grazing periods (1, 31, 57 and 88 days and two forage samples (available in pasture (AP and obtained by hand-plucking (HP were studied. The live leaf laminae (LLL, potentially digestible neutral detergent fiber (PDNDF, potentially digestible dry matter (PDDM and crude protein (CP levels were higher and dead leaf laminae (DLL, and dead stem (DS, neutral detergent fiber (NDF and indigestible NDF percentages were lower in sample of HP in relation to forage AP. The grazing period decreased linearly the LLL, PDNDF, PDDM percentages, as well as increased linearly DS and indigestible NDF levels in forages. The potential selectivity indexes (PSI of LLL and indigestible NDF increased linearly with grazing period. The PSI of live stem was smaller and the PSI of CP was higher in interim periods of grazing. The reduction in deferring period results in B. decumbens with better morphological composition and nutritional value, which favors the animal selectivity.

  19. Brachiaria sp yield and nutrient contents after nitrogen and sulphur fertilization

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    Reges Heinrichs

    2013-08-01

    Full Text Available Among the production factors, adequate fertilization is an important tool to raise the productivity of pastoral systems and consequently increase the share of Brazil in the supply chain of primary agricultural products at the global level. The objective of this study was to evaluate the interaction of nitrogen and sulfur fertilization in BRACHIARIA DECUMBENS: Stapf. The experiment in pots with Dystrophic Oxisol was evaluated in a completely randomized design with four replications in a 5 x 3 factorial arrangement, involving five N doses (0, 100, 200, 400, and 800 mg dm-3 in the form of ammonium nitrate and three S doses (0, 20 and 80 mg dm-3 in the form of calcium sulfate, with a total of 15 treatments. In the treatments with low S dose, calcium was provided as calcium chloride, to ensure a homogeneous Ca supply in all treatments. The results showed that the tiller production and dry weight of green leaves and of stems + sheaths and total dry weight were favored by the combination of N and S fertilizer, while the proportion of dry leaves was reduced. Nitrogen fertilization raised the N contents in green leaves and stems + sheaths and reduced K contents in fresh and dry leaves. The response to S rates in the N content of green leaves was quadratic.

  20. Evaluation of new hybrid brachiaria lines in Thailand. 1. Forage production and quality

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    Michael D. Hare

    2015-05-01

    Full Text Available Forty-three new hybrid bracharia lines were evaluated for forage accumulation and nutritive value in Northeast Thailand from 2006 to 2011 in experiments at 2 sites, using Mulato II hybrid brachiaria as a standard for comparison. The parameters evaluated were wet and dry season dry matter (DM accumulation, leaf:stem ratio, crude protein (CP concentration and fiber level [acid detergent fiber (ADF and neutral detergent fiber (NDF]. No lines consistently displayed superior dry season forage accumulation and leaf:stem ratio over Mulato II. In the wet seasons, 14 lines produced more DM than Mulato II but in only one wet season each. Mulato II produced forage with high leaf:stem ratio in all seasons. Many lines did have significantly higher CP concentrations and lower levels of ADF and NDF than Mulato II, but their forage accumulation and leaf:stem ratio were inferior. Four lines (BR02/1718, BR02/1752, BR02/1794 and BR02/0465 were granted Plant Variety Rights in 2011.Keywords: Cayman, Cobra, crude protein, dry matter yields, forage regrowth,  Mulato II.DOI: 10.17138/TGFT(383-93 

  1. Clinical and histopathological study of the phototoxic dermatitis in Zebu calves in grazing of Brachiaria decumbens

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    José Cardona-Álvarez

    2016-05-01

    Full Text Available Objective. The objective was to study the clinical and histopathological aspects of Phototoxic Dermatitis Secondary (PDS, secondary to ingestion of Brachiaria decumbens in Zebu calves (Bos indicus department of Cordoba, Colombia. Materials and methods. Twelve calves Zebu, male, 12 to 18 months, PDS diagnosed with clinical, histopathologically studied and laboratory exams. Results.Clinically, signs of photophobia, dehydration, progressive emaciation, icteric mucous membranes and skin lesions as res-breaking with leathery skin appearance, skin peeling and scabbing over large areas were evident. The lesions were located bilaterally in different areas of the skin in ears, perineal region, epigastric and costal. Serological tests gave the high catalytic activity of the liver enzymes AST and GGT indicating liver injury consistent with cholestasis. Histopathologically was observed in hematoxylin eosin, chronic necrotic dermatitis, in trichrome Gomori poor dermal proliferation disorganized fibroblasts, low presence of diffuse connective tissue and collagen fibers disorganized and picrosirius red / polarization areas reddish birefringence was observed was observed and greenyellow, indicating moderate presence of mature collagen type I (bright red in polarization and Type III (bright yellowish-green polarization. Conclusions. The definitive diagnosis of the disease was based on clinical features, laboratory findings and histopathological findings, being conclusive as diagnostic methods of the PDS. In the literature there are no reports of studies PDS in Zebu calves department of Córdoba and Colombia.

  2. RESPOSTA DE DUAS CULTIVARES DE ARROZ DE TERRAS ALTAS EM CONVIVÊNCIA COM Brachiaria brizantha

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    Abdias Alves De Oliveira

    2009-01-01

    Full Text Available The objective of this work was to evaluate to the sowing time of the Brachiaria brizantha forage intercrop with two upland rice cultivars on the agronomics characteristics of both species. It was used randomized blocks in experimental design arranged in factorial scheme 2x2+4, with four replicates. The first factor was constituted by the upland rice cultivars (BRS Primavera e BRSMG Curinga and the second factor by two sowing times of B. brizantha forage (simultaneous sowing between rice and forage and sowing of the forage in the flowering of the rice. The additional treatments consisted of the sole crops upland rice cultivars and B. brizantha forage for each sowing time. In rice was evaluated the height of the plants, bedding, difficulty of the harvest, the number of panicles per area, grain per panicles, percentage of full and empty grains, 100-grain mass and grain yield. In the B. brizantha forage was evaluated the height of the tillers, the total dry mass and the rate of cultural growth. It was observed that the B. brizantha forage interfered in the productivity components of both upland rice cultivars and difficult significantly the harvest of the rice. The upland rice cultivars showed small competitive capacity with the B. brizantha forage when the establishment of the forage occurred simultaneously to the rice. However, to the measure that the sowing was occurred with the established rice already, the B. brizantha forage had his growth suppressed.

  3. Weed Biomass and Weed Species Diversity of Juvenile Citrus Trees Intercrop with some Arable Crops

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    Patience Mojibade OLORUNMAIYE

    2012-02-01

    Full Text Available A preliminary study was carried out to evaluate the performances of eight crops in the intercrop of citrus with arable crops at the National Horticultural Research Institute (NIHORT Ibadan, Nigeria. Eight arable crops: maize, cucumber, sweet potato, Corchorus olitorius, large green, grain amaranth, Mucuna pruriens var. utilis, and groundnut were intercropped with young citrus trees in the early planting season of 2010 with sole citrus as control. The experiment was laid out in a completely randomized block design with three replicates. Data were collected on weed flora, weed density and weed dry weight. Results showed that the relative frequencies of weeds in all the plots were less than 4% at both 6 and 9WAP. Gomphrena celosoides, Oldenlandia corymbosa and Tridax procumbens were most preponderant in appearing in all the plots. Tridax procumbens had a consistent relative frequency (2.34% in all the plots except in citrus/maize plot (0.78% at 9 WAP. Significantly lower broadleaf weed densities were obtained in citrus/sweet potato, citrus/large green, control plot and citrus/cucumber (28.67, 45.00, 50.00 and 76.33 m-2 respectively than in citrus/groundnut plot (143.00 m-2. Similarly, significantly lower grass weed densities were produced in citrus/Mucuna and citrus/sweet potato (0.33 m-2 each plots than the control plot (11.33 m-2. Whereas citrus/corchorus plot produced significantly lower broadleaf weed dry weight (37.59 g m-2 than citrus/Mucuna plot (126.47 g m-2 at 3WAP, citrus/large green plot (16.15 g m-2 and citrus/groundnut plot (123.25 g m-2 followed the same trend at 6 WAP. Sedges dry weights were less than 7 g m-2 in all the plots compared with control plot.

  4. Effect of Different Methods of Chemical Weed Control Irrigation Regimes on Weed Biomass and Safflower Yield

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    M. Matinfar

    2011-06-01

    Full Text Available In order to investigate the effects of different weed control methods and moisture regimes on safflower (Carthamus tinctorius, a field split plot experiment based on randomized complete block design with 4 replications was conducted in Takestan Iran, during growing seasons of 2007-8. Three irrigations regimes (normal irrigation, restricted irrigation at stem elongation and restricted irrigation at  flowering stage were assigned to the main plots and nine chemical weed control method (complete hand weeding, treflan with 2 L/ha as pre plant herbicide, sonalan with 3 L/ha ad pre plant herbicide, estomp with 3 L/ha as pre plant herbicide, gallant super with 0/75 L/ha as post emergence herbicide, treflan with 2 L/ha as pre plant herbicide+ gallant super with 0/75 L/ha as post emergence herbicide, sonalan with 3 L/ha as pre plant herbicide + gallant super with 0/75 L/ha as post emergence herbicide estomp with 3 L/ha as pre plant herbicide + gallant super with 0/75 L/ha as post emergence herbicide and without hand weeding to sub- plots. At the end of growing period traits like number of head   per plant, number of seed per head, 1000 grain weight, percent of seed oil, yield of seed oil and grain yield were measured. Results indicated that treflan + gallant super treatment in restricted irrigation at stem elongation stage had the lowest dry weight of weeds. In this study maximum grain yield (2927 Kg/ha was achieved from hand weeding + usual irrigation treatments. In general treflan + gallant super treatment was the most effective treatment on safflower yield and weed control.

  5. The benefits of using quantile regression for analysing the effect of weeds on organic winter wheat

    NARCIS (Netherlands)

    Casagrande, M.; Makowski, D.; Jeuffroy, M.H.; Valantin-Morison, M.; David, C.

    2010-01-01

    P>In organic farming, weeds are one of the threats that limit crop yield. An early prediction of weed effect on yield loss and the size of late weed populations could help farmers and advisors to improve weed management. Numerous studies predicting the effect of weeds on yield have already been

  6. High-residue cultivation timing impact on organic no-till soybean weed management

    Science.gov (United States)

    A cereal rye cover crop mulch can suppress summer annual weeds early in the soybean growing season. However, a multi-tactic weed management approach is required when annual weed seedbanks are large or perennial weeds are present. In such situations, the weed suppression from a cereal rye mulch can b...

  7. Weed Identification Distribution and Mapping at Njoro and Katumani

    International Nuclear Information System (INIS)

    Mwangi, H; Alembi, D.K

    1999-01-01

    The study was a response to the need from Katumani DFRC and Njoro (NPBC) Crop protection team request for support service in identification of weed spp. in their mandated areas. From their ongoing adaptive research they encountered ceratin weed spp. which were troublesome and they could not identify and their contact farmers had expressed concern over the weed constraint. A survey in the mentioned areas were carried out in the long/short rains 1997. In the fields, the sites were selected after every 10 km. The field selected was traversed and a quadrat measuring 1m 2 was placed randomly and weeds identified. General Position System (GPS) recorded the position. Two methods of identifying weeds thus on the spot in the field in situ and unidentified weed samples were carefully collected, labelled and preserved for identification in the laboratory of NARL herbarium. Weed distribution was determined using scale 1-4 where 1=1 plant/M 2 , 2=2-5 plants/m 2 , 3=6-20 plants/m 2 ,4=>20 plants m /2. The results show identified weeds in different categories; dominant, troublesome, indigenous and weed introduced within the ten years as percieved by farmers. Developed weed maps are presented for specific districts

  8. Weed infestation of onion in soil reduced cultivation system

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    Marzena Błażej-Woźniak

    2013-12-01

    Full Text Available Field experiment was conducted in the years 1998-2000 in GD Felin. The influence of no-tillage cultivation and conventional tillage with spring ploughing on weed infestation of onion was compared. In experiment four cover crop mulches (Sinapis alba L., Vicia sativa L., Phacelia tanacetifolia B., Avena sativa L. were applied. From annual weeds in weed infestation of onion in great number Matricaria chamomilla L., and Senecio vulgaris L. stepped out. and from perennial - Agropyron repens (L.P.B. Reduced soil cultivation system (no-tillage caused the significant growth of primary weed infestation of onion in comparison with conventional tillage. In all years of investigations the executed pre-sowing ploughing limited significantly the annual weeds' number in primary weed infestation. The applied mulches from cover plants limited in considerable degree the number of primary weed infestation. In all years of investigations the most weeds stepped out on control object. Among investigated cover crop mulches Vicia sativa L. and Avena sativa L. had a profitable effect on decrease of onion`s primary weed infestation. Soil cultivation system and cover crop mulches had no signi ficant residual influence on the secondary weed infestation of onion.

  9. A non-chemical system for online weed control.

    Science.gov (United States)

    Rueda-Ayala, Victor; Peteinatos, Gerassimos; Gerhards, Roland; Andújar, Dionisio

    2015-03-30

    Non-chemical weed control methods need to be directed towards a site-specific weeding approach, in order to be able to compete the conventional herbicide equivalents. A system for online weed control was developed. It automatically adjusts the tine angle of a harrow and creates different levels of intensity: from gentle to aggressive. Two experimental plots in a maize field were harrowed with two consecutive passes. The plots presented from low to high weed infestation levels. Discriminant capabilities of an ultrasonic sensor were used to determine the crop and weed variability of the field. A controlling unit used ultrasonic readings to adjust the tine angle, producing an appropriate harrowing intensity. Thus, areas with high crop and weed densities were more aggressively harrowed, while areas with lower densities were cultivated with a gentler treatment; areas with very low densities or without weeds were not treated. Although the weed development was relatively advanced and the soil surface was hard, the weed control achieved by the system reached an average of 51% (20%-91%), without causing significant crop damage as a result of harrowing. This system is proposed as a relatively low cost, online, and real-time automatic harrow that improves the weed control efficacy, reduces energy consumption, and avoids the usage of herbicide.

  10. Efeitos dos períodos de competição do mato na cultura do amendoim: II. Safra das águas Effects of weed competition periods on peanut: II. Wet season crop

    Directory of Open Access Journals (Sweden)

    EDISON MARTINS PAULO

    2001-01-01

    Full Text Available O presente trabalho foi realizado na safra das águas de 1989, no Núcleo de Agronomia da Alta Paulista, em Adamantina (SP para estudar o efeito de diferentes períodos de competição do mato no amendoim. Adotou-se o delineamento estatístico de blocos ao acaso, com quatro repetições e 22 tratamentos. Os tratamentos resultaram da combinação da presença e da ausência do mato a partir do início da cultura, com as seguintes épocas de remoção da flora infestante: 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 e 100 dias após a semeadura. As parcelas foram constituídas por quatro linhas de amendoim, perfazendo 6 m² de área útil. As principais plantas daninhas encontradas na área experimental foram: Cyperus lanceolatus Poir, Commelina benghalensis L., Brachiaria decumbens Stapf., Amaranthus viridis L., Eleusine indica (L. Gaertn., Portulaca oleracea L., Digitaria horizontalis Willd. e Solanum americanum Mill. A convivência do mato diminuiu a produção de vagens, de grãos e a população do amendoim na colheita. Não se observou efeito do mato sobre o rendimento de grãos e sobre a matéria seca acumulada pela parte aérea do amendoim. Capinas aplicadas aos 13 e 67 dias após a semeadura, respectivamente para os sistemas sem e com mato a partir da semeadura, foram suficientes para a obtenção de produção de vagens de amendoim estatisticamente igual à obtida pela cultura mantida sem competição, durante todo o ciclo. Os componentes da produção do amendoim foram favorecidos com a aplicação do sistema sem mato, a partir do início da cultura.The present research was carried out at the Núcleo de Agronomia da Alta Paulista, in Adamantina, State of Sao Paulo, Brazil, to study the effects of different periods of weed competition with peanut.The treatments were all possible combinations among the presence/absence of weeds (at the sowing time and the following periods of weed removal: 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 days

  11. SISTEMAS DE MANEJO DO SOLO: SOJA [Glycine max (L.] CONSORCIADA COM Brachiaria decumbens (STAPF SOIL MANAGEMENT SYSTEMS: SOYBEAN [Glycine max (L.] INTERCROPPED WITH Brachiaria decumbens (STAPF

    Directory of Open Access Journals (Sweden)

    Emanuel da Silva Barros

    2011-01-01

    vagem, número de grãos por planta, massa de 1.000 grãos e produtividade; e 2 B. decumbens: composição química das plantas, além do acúmulo de matéria seca, em cinco épocas de amostragens. Os sistemas de manejo do solo influenciaram o estande de plantas e a concentração de P, Cu, Fe e Zn, na soja, além do S, na Brachiaria decumbens. O sistema plantio direto apresentou maior produtividade de grãos e produção de fitomassa de B. decumbens, nas condições edafoclimáticas de Rio Largo (AL.

    PALAVRAS-CHAVE: Plantio direto; integração lavoura-pecuária; cultivo mínimo.

    The aim of this study was to evaluate the effects of different soil management systems on the soybean yield components intercropped or not with Brachiaria

  12. Water management as a key component of integrated weed management

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    Antonio Berti

    2010-09-01

    Full Text Available Water management within the cropping system is a key factor for an integrated weed management. Soil moisture affects seed persistence and seed dormancy, thus influencing their germination, the establishment of seedlings as well as the competition at adult stage and the number, vitality and dormancy of the new seeds produced by the weeds. The interactions among water availability and competition are very complex and still not fully understood. A research effort in this sector should the be very relevant for the development of new approaches of weed management, such as “Ecological weed management”, aiming to reduce weed density and competitiveness and, in the medium term, to prevent undesired modifications of the weed flora.

  13. Evaluation of interspecific hybrids and cultivars of Brachiaria spp. submitted to sourcers and levels of nitrogen fertilization

    Directory of Open Access Journals (Sweden)

    Márcia Atauri Cardelli Lucena

    2012-12-01

    Full Text Available The management of nitrogen supply (N is a very important issue concerned to plant growth and the environment healthy. For farmers, to know how much N the plant requires enables the application of appropriate amounts of nitrogen fertilizer, maximizing the use of this material. The availability of N has been identified as one of the main limiting factors, but also a management tool in the production of grasses. The nitrogen in the soil either, as a constituent of organic matter or in the mineral form (ammonium and nitrate, has a limited supply and can be depleted rapidly in a few crops. The aim of this study was to evaluate the effects of sources and nitrogen levels in four genotypes of Brachiaria (Brachiaria brizantha cv. Marandu, Brachiaria brizantha cv. Piata and two interspecific hybrids of Brachiaria spp on the total and the leaf dry matter production, leaf percentage and leaf: stem ratio. The soil was an Psament-Entisol, coming from a pasture of Brachiaria decumbens with low organic matter content. The experiment was conducted in greenhouse, in Nova Odessa, Sao Paulo, from October 2009 to April 2010. The experimental design was in randomized complete blocks and the treatments were arranged in a factorial 4 x 2 x 4, four genotypes of Brachiaria , two N sources (urea and ammonium nitrate and four nitrogen rates (0, 75, 150 or 225 mg dm-3 with five replicates, totaling 160 pots with a capacity of 3.34 dm3 of soil. Two cuts were performed in the plants. After the second cut a soil sample was collected from each experimental unit. Two evaluations were performed on plants. The first one 52 days after sowing, and the second 56 days after the first cut. Data were analyzed by the mixed procedure of SAS V. 9.2; average qualitative factors were compared by Tukey test at 5% probability. The degrees of freedom related to N rates (quantitative factor were decomposed into orthogonal polynomials; to obtain the best equation fits the data. The variables

  14. Hábito de pastejo de novilhas em pastagens do gênero Brachiaria - DOI: 10.4025/actascianimsci.v29i4.992 Grazing habits of heifers on pastures of Brachiaria genus - DOI: 10.4025/actascianimsci.v29i4.992

    Directory of Open Access Journals (Sweden)

    Juliana Silva de Oliveira

    2008-03-01

    Full Text Available Objetivou-se avaliar o comportamento de novilhas pastejando Brachiarias, em sistema de lotação contínua. O delineamento experimental foi o inteiramente casualizado, com duas espécies de gramíneas representando os tratamentos, cada um com cinco repetições. Foram utilizadas novilhas leiteiras, com peso vivo médio de 315 kg. O período experimental foi de 30 dias, sendo 20 para adaptação dos animais e 10 para avaliações, que consistiram de três, com duração de 24 horas cada, em intervalos de cinco dias. As novilhas pastejaram menos tempo no pasto de Brachiaria brizantha, com tempo de 10,56 horas, enquanto que o pastejo na Brachiaria decumbens foi de 11,51 horas. A quantidade de bocados por minuto foi menor para a Brachiaria decumbens, 31,27 horas, enquanto para a Brachiaria brizantha, as novilhas pastejaram com uma taxa de bocados de 37,72 bocados por minuto. As novilhas apresentam comportamento diferenciado nas gramíneas estudadas, elevando o tempo de pastejo na Brachiaria decumbens como forma de compensar um comportamento de pastejo mais seletivo.This work aimed to evaluate the grazing behavior of heifers on Brachiarias, in continuous stocking with variable stocking rates. The experimental design was completely randomized, with two pastures representing the treatments, each with five replications. Dairy heifers were used, with an average weight of 315 kg. The experiment lasted for 30 days, being 20 for adaptation of the animals and 10 for the three evaluations, each with a duration of 24 hours, in five-day intervals. Heifers grazed less time on the pasture of Brachiaria brizantha (10.56 hours, while the grazing on Brachiaria decumbens lasted 11.51 hours. Nevertheless, there was no difference for total bites. Heifers presented different grazing on the evaluated pastures, increasing grazing time on Brachiaria decumbens to adjust for a more selective behavior.

  15. Photosynthetic activity of cassava plants under weed competition Atividade fotossintética de plantas de mandioca submetidas a competição com plantas daninhas

    Directory of Open Access Journals (Sweden)

    I. Aspiazú

    2010-01-01

    Full Text Available The objective of this work was to evaluate characteristics associated with the photosynthetic activity of cassava plants under weed competition. The trial was carried out under field conditions, and experimental units consisted of 150 dm³ fiberglass boxes containing red yellow Latosol, previously corrected and fertilized. Treatments consisted in the cultivation of cassava plants which were free of weed competition and associated with three weed species: Bidens pilosa, Commelina benghalensis or Brachiaria plantaginea. After manioc sprouting started, 15 days after being planted, weeds that had been sown when manioc was planted were thinned, there were then eight plants left per experimental unit in accordance with specified treatments: cassava free of competition, cassava competing with B. pilosa, cassava competing with C. benghalensis and cassava competing with B. plantaginea. Sixty days after crop emergence leaf internal CO2 concentration (Ci, leaf temperature at the time of evaluation (Tleaf and photosynthetic rate (A were evaluated, also the CO2 consumption rate (ΔC of cassava plants was calculated. A correlation matrix between variables was also obtained. All characteristics associated with photosynthesis in cassava plants were influenced by weed species. Cassava was more affected by B. pilosa and B. plantaginea in which concerns its exposition to solar radiation and water, while C. benghalensis seems to mostly affect the composition of incident light on the culture, allowing cassava to anticipate imposition when competing, even before it reaches harmful levels.Objetivou-se com este trabalho avaliar características associadas à atividade fotossintética de plantas de mandioca sob competição ou não com plantas daninhas. O experimento foi realizado em condições de ambiente aberto, sendo as unidades experimentais compostas por vasos de fibra de vidro de 150 dm³ preenchidos com Latossolo Vermelho Amarelo, previamente adubado. Os

  16. Can Arbuscular Mycorrhizal Fungi Reduce the Growth of Agricultural Weeds?

    Science.gov (United States)

    Veiga, Rita S. L.; Jansa, Jan; Frossard, Emmanuel; van der Heijden, Marcel G. A.

    2011-01-01

    Background Arbuscular mycorrhizal fungi (AMF) are known for their beneficial effects on plants. However, there is increasing evidence that some ruderal plants, including several agricultural weeds, respond negatively to AMF colonization. Here, we investigated the effect of AMF on the growth of individual weed species and on weed-crop interactions. Methodology/Principal Findings First, under controlled glasshouse conditions, we screened growth responses of nine weed species and three crops to a widespread AMF, Glomus intraradices. None of the weeds screened showed a significant positive mycorrhizal growth response and four weed species were significantly reduced by the AMF (growth responses between −22 and −35%). In a subsequent experiment, we selected three of the negatively responding weed species – Echinochloa crus-galli, Setaria viridis and Solanum nigrum – and analyzed their responses to a combination of three AMF (Glomus intraradices, Glomus mosseae and Glomus claroideum). Finally, we tested whether the presence of a crop (maize) enhanced the suppressive effect of AMF on weeds. We found that the growth of the three selected weed species was also reduced by a combination of AMF and that the presence of maize amplified the negative effect of AMF on the growth of E. crus-galli. Conclusions/Significance Our results show that AMF can negatively influence the growth of some weed species indicating that AMF have the potential to act as determinants of weed community structure. Furthermore, mycorrhizal weed growth reductions can be amplified in the presence of a crop. Previous studies have shown that AMF provide a number of beneficial ecosystem services. Taken together with our current results, the maintenance and promotion of AMF activity may thereby contribute to sustainable management of agroecosystems. However, in order to further the practical and ecological relevance of our findings, additional experiments should be performed under field conditions. PMID

  17. BIOLOGICAL CONTROL OF WEEDS BY MEANS OF PLANT PATHOGENS

    OpenAIRE

    Marija Ravlić; Renata Baličević

    2014-01-01

    Biological control is the use of live beneficial organisms and products of their metabolism in the pests control. Plant pathogens can be used for weed control in three different ways: as classical, conservation and augmentative (inoculative and inundated) biological control. Inundated biological control involves the use of bioherbicides (mycoherbicides) or artificial breeding of pathogens and application in specific stages of crops and weeds. Biological control of weeds can be used where chem...

  18. Efeitos fitotóxicos do fluoreto na morfoanatomia foliar de Brachiaria brizantha (Hochst. ex A. Rich. Stapf e Brachiaria decumbens Stapf (Poaceae Phytotoxic effects of fluoride in leaf morpho-anatomy of Brachiaria brizantha (Hochst. Ex A. Rich. Stapf and Brachiaria decumbens Stapf (Poaceae

    Directory of Open Access Journals (Sweden)

    Alice Pita-Barbosa

    2009-12-01

    Full Text Available Visando avaliar os efeitos do fluoreto sobre capim-braquiária, plantas de Brachiaria brizantha e B. decumbens foram submetidas a nevoeiros simulados com fluoreto (10 µg ml-1. Amostras foliares de porções aparentemente sadias foram coletadas 24 horas após a última exposição para análises microscópicas. Folhas, raízes e rizomas foram submetidos à quantificação do teor de fluoreto. As folhas apresentaram necroses pequenas e esparsas. Somente as folhas acumularam fluoreto, apresentando teores 4,4 e 5,2 vezes maiores que no tratamento controle, em B. brizantha e B. decumbens, respectivamente, não havendo diferença no potencial acumulador das duas espécies. As principais alterações micromorfológicas observadas foram lesões próximas aos tricomas, sugerindo que estes sejam as vias preferenciais de entrada do poluente nas plantas. Porções foliares, visualmente sadias, de ambas as espécies apresentaram danos microscópicos antes do surgimento de sintomas, havendo perda da turgidez das células buliformes em B. brizantha e de todos os tecidos em B. decumbens. Alterações micromorfométricas foram observadas somente em B. decumbens, indicando sua maior sensibilidade ao fluoreto, em comparação com B. brizantha. A realização de experimentos de longa duração será fundamental para elucidar o potencial bioacumulador de B. brizantha.To assess the effects of fluoride on signal grass, plants of Brachiaria brizantha and B. decumbens were submitted to simulated fluoride fog (10 µg ml-1. Leaf fragments from apparently healthy portions were colleted 24 hours after the last exposure and used for microscopic analysis. Roots, leaves and rhizomes were submitted to fluoride content quantification. The leaves presented small, sparse necroses. The accumulation of fluoride was observed on the leaves only. B. brizantha and B. decumbens presented, respectively, 4.4 and 5.2 times more fluoride than the control treatment. No difference was

  19. Soil chemical atributtes on brachiaria spp in integrated crop livestock system

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    Valdinei Tadeu Paulino

    2013-12-01

    Full Text Available Integrated crop-livestock systems have attracted more interest in the last few years due to their capacity of improving stability and sustainability of agricultural systems when compared to more specialized production ones. The crop-livestock integration is an effective technique, but complex to maintain pasture productivity and its recovery, whose efficiency depends on soil physical management and its chemical fertility. Regarding the soil fertility, the corrective practices generally begin with the liming due to the high acidity of most Brazilian soils and low levels of Ca and Mg in the exchange complex and high Al saturation. In areas of crop-livestock systems, liming corrects the surface acidity potential. However, this practice can leave the subsoil with excess aluminum and lack of calcium, which inhibit root growth and affect the absorption of water and nutrients. The application of gypsum allows the improvement of the subsoil, reducing Al saturation and increasing levels of calcium and sulfur. The aim of this study was to investigate changes in the soil chemical properties of a Haplorthox soil in integrated crop-livestock system (ICL with Brachiaria brizantha cv. Marandu and Piatã, Brachiaria ruziziensis with gypsum and liming application. This study was conducted at the Instituto de Zootecnia, Nova Odessa/SP, a pasture established on a soil with medium texture (61.4% sand, silt 14.6% and 24.0% clay. The treatment plots consisted on integration crop-livestock (ICL cultivated - maize and B. Marandu,  ICL - maize and B. ruziziensis, ICL - maize and B. Piatã and an untreated control group (control - without liming and fertilization grazed pasture throughout the year, located immediately adjacent to the ICL evaluation, which was cultivated for 25 years with B. brizantha cv. Marandu. All pastures were desiccated in October with glyphosate-based herbicide (4 liters per hectare. Then gypsum (1.2 Mg ha-1 and liming (1.2 Mg ha-1 were applied

  20. Establishment and Early Growth of Willow at Different Levels of Weed Competition and Nitrogen Fertilization

    DEFF Research Database (Denmark)

    Edelfeldt, Stina; Lundkvist, Anneli; Forkman, Johannes

    2016-01-01

    To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora (Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow...... gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed...... biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation...

  1. The mathematical method of studying the reproduction structure of weeds and its application to Bromus sterilis

    NARCIS (Netherlands)

    Wang, J.; Hansen, P.K.; Christensen, S.; Qi, G.Z.

    2004-01-01

    This article discusses the structure of weed reproduction incorporating the application of a mathematical model. This mathematical methodology enables the construction, testing and application of distribution models for the analysis of the structure of weed reproduction and weed ecology. The

  2. Evaluation of dairy cows intake behavior grazing Brachiaria brizantha fed different levels of concentrate at diet

    Directory of Open Access Journals (Sweden)

    Fabrício Bacelar Lima Mendes

    2013-12-01

    Full Text Available The objective with this research was to evaluate the dairy cows intake behavior grazing Brachiaria brizantha submitted to different levels of concentrate supplementation in the diet. Used 16 lactating cows ½ Holstein x ½ Zebu, with an average of 80 ±10.14 days of lactation and body weight of 454.7 ± 54.51 kg. The animals were distributed in four treatments, using a 4x4 Latin square. The evaluation of behavior was done every ten minutes, during 24 hours on the 16th day of period. We used analysis of variance and regression probability of 0.05. The time spent grazing, ruminating and other activities, the numbers of grazing, ruminating, of bites per day and chews per cake, the grazing times, total power and total chewing, bit rate, time to swallow; time per bolus ruminated; chewing speed and power efficiency for NDF were not altered by increased levels of concentrate. The time of trough, the trough period, the bit size, the chews time for bolus, feeding efficiency for DM, NFC, and TDN and rumination efficiency linearly increased. Periods of rumination, deglutition bits, number of rumination chews per day, decreased linearly with increasing levels of concentrate. Significant quadratic effect of concentrate level on the number of periods in other activities and over time on other activities. Supplementation with 33.8% concentrate in the diet of cows grazing not promote changes in the activity of grazing, ruminating and other activities, but increases the time of trough. The increase in concentrate diet improves the efficiencies of feeding and rumination

  3. Tóxidad de cadmio y plomo en pasto tanner Brachiaria arrecta

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    Manuel Peláez

    2014-12-01

    Full Text Available Se evaluó fisiopatías en Brachiaria arrecta expuestas a contenidos tóxicos de cadmio y plomo en el invernadero de la Universidad Nacional de Colombia Sede Palmira, se doparon plántulas sanas de 20 días de edad bajo cultivo hidropónico. El objetivo fue describir síntomas crecientes por intoxicación con el diseño de una escala valorativa de daños crecientes, adicionalmente se evaluaron cambios histológicos de raíz tallo y hojas mediante microscopia de luz de alta resolución (MLAR. Las plantas fueron sometidas a estrés abiótico con los tratamientos de sales de CdCl2 en concentración de 10 ppm, y de Pb (NO32 500 ppm, respectivamente. Los resultados principales mostraron un mayor detrimento cuando las plantas fueron expuestas al metal plomo que al cadmio en las raíces, tallos y hojas. Se apreciaron deformaciones extremas en paredes celulares de las células del cortex y en la endodermis de la raíz; en las hojas los daños fueron notorios para ambos metales sobre todo en el parénquima clorofílico y en la deformación de paredes de la epidermis tanto en haz como envés; en los tallos aparecieron deformaciones de las células del parénquima de relleno cuando ocurre bioacumulación intensa de plomo. Estos resultados sugieren que la bioconcentración en los tejidos vegetales ocasiona trastornos histológicos, que pueden involucrar una red trófica y por consiguiente consecuencias en la Salud Pública.

  4. Phytotoxic substances with allelopathic activity may be central to the strong invasive potential of Brachiaria brizantha.

    Science.gov (United States)

    Kato-Noguchi, Hisashi; Kobayashi, Ai; Ohno, Osamu; Kimura, Fukiko; Fujii, Yoshiharu; Suenaga, Kiyotake

    2014-04-15

    The grass Brachiaria brizantha, native to eastern Africa, becomes naturalized and dominant quickly in the non-native areas. It was hypothesized that phytotoxic chemical interaction between this plant and native plants may play an important role in the invasion of B. brizantha. However, no potent phytotoxic substance has been reported in this species. Therefore, we investigated possible allelopathic activity and searched for phytotoxic substances with allelopathic activity in B. brizantha. An aqueous methanol extract of B. brizantha inhibited the growth of roots and shoots of garden cress (Lepidium sativum), lettuce (Lactuca sativa), timothy (Phleum pratense) and ryegrass (Lolium multiflorum) seedlings. The extract was purified by several chromatographic runs and three allelopathically active substances were isolated and identified by spectral analysis as (6R,9R)-3-oxo-α-ionol, (6R,9S)-3-oxo-α-ionol and 4-ketopinoresinol. (6R,9R)-3-Oxo-α-ionol and (6R,9S)-3-oxo-α-ionol inhibited root and shoot growth of garden cress at concentrations greater than 30 and 10 μM, respectively. The activity of (6R,9S)-3-oxo-α-ionol was 5.3- to 6.2-fold that of (6R,9R)-3-oxo-α-ionol. The stereochemistry of the hydroxyl group at position C-9 may be important for the inhibitory activities of those compounds. 4-Ketopinoresinol inhibited root and shoot growth of garden cress at concentrations greater than 30 μM. The growth inhibitory activity of (6R,9S)-3-oxo-α-ionol was the greatest and followed by 4-ketopinoresinol and (6R,9R)-3-oxo-α-ionol. These results suggest that those phytotoxic substances may contribute to the allelopathic effect caused by B. brizantha and may be involved in the invasion of B. brizantha. Copyright © 2013 Elsevier GmbH. All rights reserved.

  5. Effect of liming and fertilizer on mineral content and productivity of Brachiaria Decumbens grass forage

    International Nuclear Information System (INIS)

    Armelin, M.J.A.; Saiki, M.

    2007-01-01

    To restore a degraded pasture of Brachiaria decumbens, located in Sao Carlos - SP, southeastern Brazil, under altitude tropical climate, an experiment was carried out to study the effects of limestone, buried or not buried in the soil, and fertilizer use on mineral content and forage yield, after 3 years of treatment. Limestone and phosphorus were applied once, one month before starting. NK were applied after each cutting, for fertilized plots, four to five times a year. Experimental design was a random block (100 m 2 ), with 6 replications and 4 treatments. Each block received 4 t/ha of limestone, except the control. Forage samples were collected 14 cm above soil surface. Instrumental neutron activation analysis (INAA) followed by gamma-ray spectrometry was the analytical method used to determine the mineral contents. Dry matter yield was affected positively with liming when compared with the limestone control, but the effect of limestone use was more pronounced with the concomitant use of NK fertilizer. The contents of Ca, Cs, Fe, La, Mg, Rb, Sc, Sm and Th in forage were negatively affected with the NK use, perhaps due to a dilution effect, while a reverse were observed for K, Cl, perhaps due to input of KCl, besides Br, Mn and Se. It seems that limestone is not a key input to restore degraded tropical pastureland, grown on acid soils, when nitrogen is lacking. INAA allowed the monitoring of some not routine elements that may be under observation to avoid potential plant nutritional disorders in production systems with high limestone and fertilizer use. (author)

  6. GERMINATION AND DEVELOPMENT OF BRACHIARIA SEEDLING IN TEXTURES OF SOIL AND SOWING DEPTH

    Directory of Open Access Journals (Sweden)

    J. H. Castaldo

    2016-09-01

    Full Text Available The agriculture expansion at Brazil is turning to lower clay index soils and consequently, less organic matter content and cation exchange capacity. To overcome those deficiencies, an intense organic matter addition in these soils may be a solution, and this solution is positive when using a crop-livestock integration with corn-pasture dual crop planted on winter. However, to establish this dual-crop system, there is a need to study the behavior of seeds and seedlings of Brachiaria ruziziensis sown in greater depths than normally recommended. Thus, this work aimed to determine the best depth of sowing B. ruziziensis in sandy and loamy soils of Umuarama region, studying the germination and early development of seedlings. The work was held in pots of 12 cm diameter x 12 cm deep, filled with 2 types of soil, a sandy and clay ones with 30 B. ruziziensis seeds sown each pot in five sowing depths: 0, 2, 4, 6 and 8 cm. After 16 days, the number of emerged seedlings was evaluated to set up the germination rate of each treatment, after that, the plants where leveled to 4 each pot, those were cultivated for another 45 days to evaluate the fresh and dried masses of plants and roots, the height of the plants and average length of roots. The sowing depth with higher percentage of germination estimated was 2.65 cm to sandy and 3.02 cm to clay soil. At seedlings development, there was a standard, with better development seedling at lower sowing depths on clay soil and better developments at higher sowing depths in sandy soil.

  7. EVALUACIÓN DE LA BIOACUMULACIÓN Y TOXICIDAD DE CADMIO Y MERCURIO EN PASTO LLANERO (Brachiaria dictyoneura)

    OpenAIRE

    ARROYAVE Q, Catalina; ARAQUE M, Pedronel; PELAEZ J, Carlos A

    2010-01-01

    Se estudia la transferencia de mercurio y cadmio desde el sistema suelo hacia Brachiaria dictyoneura en función de la capacidad bioindicadora y bioacumuladora. Durante la evaluación de cadmio en B. dictyoneura se observó una disminución en el crecimiento del 65%. La toxicidad de cadmio se correlaciona con la acumulación consecutiva del catión durante el tiempo de monitoreo. En el tratamiento con mercurio, a partir de los 30 días de exposición, se observó disminución en el contenido del catión...

  8. Oxidizable carbon and humic substances in rotation systems with brachiaria/livestock and pearl millet/no livestock in the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    A. Loss

    2013-02-01

    Full Text Available The crop-livestock integration system significantly increases the carbon content in chemical fractions of soil organic matter (SOM. This study aimed to evaluate chemical indicators of SOM attributes for sites under brachiaria/livestock and pearl millet/no livestock in Goias, Brazil. A third area covered with natural Cerrado vegetation (Cerradão served as reference. Soil was randomly sampled at 0-5, 5-10, 10-20 and 20-40 cm. Total organic carbon stocks (TOC, oxidizable carbon fractions (OCF (F1>F2>F3>F4, carbon content in the humin (C-HUM, humic acid (C-HAF and fulvic acid (C-FAF fractions were evaluated. F1/F4, F1+F2/F3+F4, C-HAF/C-FAF and (C-HAF+C-FAF/C-HUM indices were calculated, as well as stocks chemical SOM fractions. Brachiaria/livestock produced greater TOC stocks than pearl millet/no livestock (0-5, 5-10 and 10-20 cm. In terms of OCF, brachiaria/livestock generally exhibited higher levels in F1, F2, F4 and F1/F4 than pearl millet/no livestock. C-HUM (0-10 cm and C-HAF (0-20 cm stocks were larger in brachiaria/livestock than pearl millet/no livestock. Compared to the Cerradão, brachiaria/livestock locations displayed higher values for TOC (5-10 and 10-20 cm, C-HAF and C-HAF/C-FAF (5-10 cm stocks. TOC, C-HAF stock and OCF show that land management with brachiaria/livestock was more efficient in increasing SOM than pearl millet/no livestock. Moreover, when compared with pearl millet/no livestock, brachiaria/livestock provided a more balanced distribution of very labile (F1 and recalcitrant (F4 carbon throughout soil layers, greater SOM humification. Brachiaria/livestock leads to higher values of F1 and F4 in depth when compared to pearl millet/livestock and provides a more homogeneous distribution of C-FAF and C-HAF in depth compared to Cerradão.

  9. Weeds in spring cereal fields in Finland - a third survey

    Directory of Open Access Journals (Sweden)

    J. SALONEN

    2008-12-01

    Full Text Available A survey of weeds in spring cereal fields was conducted in 16 regions of southern and central Finland in 1997-1999. Data were collected from conventional and organic farms, both of which applied their normal cropping practices. A total of 690 fields were investigated by counting and weighing the weed species from ten sample quadrats 0.1 m2 in size in late July - early August. Altogether 160 weed species were found, of which 134 were broad-leaved and 26 grass species. The total number of weed species ranged from 41 to 84 between regions. In organically farmed fields, the average species number was 24 and in conventionally farmed fields 16. The most frequent weed species were Viola arvensis 84%, Stellaria media 76% and Galeopsis spp. 70%. Only 18 species exceeded the frequency level of 33%. The average density of weeds was 136 m-2 (median= 91 in sprayed conventional fields, 420 m-2 (374 in unsprayed conventional fields and 469 m-2 (395 in organic fields. The average air-dry above-ground biomass of weeds was 163 kg ha-1 (median=63, 605 kg ha-1 (413 and 678 kg ha-1 (567, respectively. Weed biomass accounted for 3% of the total biomass of the crop stand in sprayed conventional fields and for 17% in organic fields. Elymus repens, the most frequent grass species, produced the highest proportion of weed biomass.

  10. Biological Efficacy of Herbicides for Weed Control in Noncropped Areas

    Directory of Open Access Journals (Sweden)

    Tsvetanka Dimitrova

    2009-01-01

    Full Text Available An increasing problem facing agricultural producers is the invasion of weeds, perennial in particular, so that implementation of industrial technologies is impossible without their highly efficient and rational control. For the purpose of studying efficient herbicides for weed control in noncropped areas (stubbles, a biological study of five total systemic herbicides was conducted in areas under natural weed infestation and pressure from othersurrounding weeds at the Institute of Forage Crops in Pleven in 2005-2007. The trials were carried out in field conditions using the block method with plot size of 20 m². Treatment was conducted at the predominant stage of budding of perennial dicotyledonous weeds and earing of monocotyledonous weeds. Herbicidal efficacy was recorded on the EWRS 9-score scale (0-100% killed weeds = score 9-1. It was found that treatment of noncropped areas (stubbles with the total systemic herbicides Touchdown System 4 (360 g/l glyphosate; Cosmic (360 g/l glyphosate; Roundup Plus (441 g/l glyphosate potassium salt; Leon 36 SL (360 g/l glyphosate and Glyphos Super 45 SL (450 g/l glyphosate was highly efficient, so that it was a successful element of a strategy for controlling weeds of different biological groups, and was especially effective against perennial weeds.

  11. Problems and achievements of cotton (Gossypium Hirsutum L. weeds control

    Directory of Open Access Journals (Sweden)

    T. Barakova

    2017-09-01

    Full Text Available Abstract. Weed control in the cultivation of cotton is critical to the yield and quality of production. The influence of economically important weeds was studied. Chemical control is the most effective method of weed control in cotton but much of the information on it relates to primary weed infestation. Problems with primary weed infestation in cotton have been solved to a significant extent. The question of secondary weed infestation with annual and perennial graminaceous weeds during the period of cotton vegetation is also determined largely by the use of antigraminaceous herbicides. The data related to herbicides to effectively control secondary germinated broadleaf weeds in conventional technology for cotton growing are quite scarce, even globally. We are still seeking effective herbicides for control of these weeds in cotton crops. Studies on their influence on the sowing characteristics of cotton seed and the quality of cotton fiber are still insufficient. In the scientific literature there is not enough information on these questions. The combinations of herbicides, as well as their tank mixtures with fertilizers or plant growth regulators are more efficient than autonomous application. Often during their combined application higher synergistic effect on yield is produced. There is information about cotton cultivars resistant to glyphosate. These cultivars are GMO and they are banned within the European Union, including Bulgaria.

  12. Weed control technology for environmentally, economically and socially sustainable agriculture

    International Nuclear Information System (INIS)

    Khan, A.R.; Srivastava, R.C.; Ghorai, A.K.; Singh, S.R.

    2001-04-01

    Studies were conducted through a series of experiments for five consecutive wet seasons with a variety of alternative biological weed control techniques by means of soil solarization. This is a method of heating soil surface by using transparent polyethylene sheets placed on soil surface to trap solar radiation. This raises soil temperature to a level lethal for many soil borne pathogens and weed seeds, thus killing weeds before crop emergence. The use of black low density polyethylene sheets reduces weed growth and increases rice yield

  13. Development of Weeds Density Evaluation System Based on RGB Sensor

    Science.gov (United States)

    Solahudin, M.; Slamet, W.; Wahyu, W.

    2018-05-01

    Weeds are plant competitors which potentially reduce the yields due to competition for sunlight, water and soil nutrients. Recently, for chemical-based weed control, site-specific weed management that accommodates spatial and temporal diversity of weeds attack in determining the appropriate dose of herbicide based on Variable Rate Technology (VRT) is preferable than traditional approach with single dose herbicide application. In such application, determination of the level of weed density is an important task. Several methods have been studied to evaluate the density of weed attack. The objective of this study is to develop a system that is able to evaluate weed density based on RGB (Red, Green, and Blue) sensors. RGB sensor was used to acquire the RGB values of the surface of the field. An artificial neural network (ANN) model was then used for determining the weed density. In this study the ANN model was trained with 280 training data (70%), 60 validation data (15%), and 60 testing data (15%). Based on the field test, using the proposed method the weed density could be evaluated with an accuracy of 83.75%.

  14. Weed control technology for environmentally, economically and socially sustainable agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Khan, A R [Directorate of Water Management Research, Indian Council of Agricultural Research (ICAR), Walmi Complex, Phulwari Sharif, Patna, Bihar (India); [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Srivastava, R C [Water Technology Centre for Eastern Region (ICAR), Bhubaneswar (India); Ghorai, A K [CRIJAF (ICAR), Barrackpore, West Bengal (India); Singh, S R [Directorate of Water Management Research, Indian Council of Agricultural Research (ICAR), Walmi Complex, Phulwari Sharif, Patna, Bihar (India)

    2001-04-01

    Studies were conducted through a series of experiments for five consecutive wet seasons with a variety of alternative biological weed control techniques by means of soil solarization. This is a method of heating soil surface by using transparent polyethylene sheets placed on soil surface to trap solar radiation. This raises soil temperature to a level lethal for many soil borne pathogens and weed seeds, thus killing weeds before crop emergence. The use of black low density polyethylene sheets reduces weed growth and increases rice yield.

  15. Herbicide-resistant weed management: focus on glyphosate.

    Science.gov (United States)

    Beckie, Hugh J

    2011-09-01

    This review focuses on proactive and reactive management of glyphosate-resistant (GR) weeds. Glyphosate resistance in weeds has evolved under recurrent glyphosate usage, with little or no diversity in weed management practices. The main herbicide strategy for proactively or reactively managing GR weeds is to supplement glyphosate with herbicides of alternative modes of action and with soil-residual activity. These herbicides can be applied in sequences or mixtures. Proactive or reactive GR weed management can be aided by crop cultivars with alternative single or stacked herbicide-resistance traits, which will become increasingly available to growers in the future. Many growers with GR weeds continue to use glyphosate because of its economical broad-spectrum weed control. Government farm policies, pesticide regulatory policies and industry actions should encourage growers to adopt a more proactive approach to GR weed management by providing the best information and training on management practices, information on the benefits of proactive management and voluntary incentives, as appropriate. Results from recent surveys in the United States indicate that such a change in grower attitudes may be occurring because of enhanced awareness of the benefits of proactive management and the relative cost of the reactive management of GR weeds. Copyright © 2011 Society of Chemical Industry.

  16. Weed Growth Stage Estimator Using Deep Convolutional Neural Networks

    DEFF Research Database (Denmark)

    Teimouri, Nima; Dyrmann, Mads; Nielsen, Per Rydahl

    2018-01-01

    This study outlines a new method of automatically estimating weed species and growth stages (from cotyledon until eight leaves are visible) of in situ images covering 18 weed species or families. Images of weeds growing within a variety of crops were gathered across variable environmental conditi...... in estimating the number of leaves and 96% accuracy when accepting a deviation of two leaves. These results show that this new method of using deep convolutional neural networks has a relatively high ability to estimate early growth stages across a wide variety of weed species....

  17. Critical Period of Weed Control in Aerobic Rice

    Science.gov (United States)

    Anwar, M. P.; Juraimi, A. S.; Samedani, B.; Puteh, A.; Man, A.

    2012-01-01

    Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return. PMID:22778701

  18. Integrated Weed Management Strategies for Control of Hydrilla

    National Research Council Canada - National Science Library

    Nelson, Linda S; Shearer, Judy F

    2009-01-01

    ...), and the fungal pathogen Mycoleptodiscus terrestris (Gerd.) Ostazeski, applied alone and in combination with one another, as an integrated weed management strategy against the nuisance aquatic plant, hydrilla...

  19. Prediction of the competitive effects of weeds on crop yields based on the relative leaf area of weeds

    DEFF Research Database (Denmark)

    Lotz, L. A. P.; Christensen, Svend; Cloutier, D.

    1996-01-01

    . alba whereas the density model did not. A parameter that allows the maximum yield loss to be smaller than 100% was mostly not needed to describe the effects of weed competition. The parameter that denotes the competitiveness of the weed species with respect to the crop decreased the later the relative......For implementation of simple yield loss models into threshold-based weed management systems, a thorough validation is needed over a great diversity of sites. Yield losses by competition wsth Sinapis alba L. (white mustard) as a model weed, were studied in 12 experiments in sugar beet (Beta vulgaris...... L.) and in 11 experiments in spring wheat (Triticum aestivum L.). Most data sets were heller described by a model based on the relative leaf area of the weed than by a hyperbolic model based on weed density. This leaf area model accounted for (part of) the effect of different emerging times of the S...

  20. Determining treatment frequency for controlling weeds on traffic islands using chemical and non-chemical weed control

    DEFF Research Database (Denmark)

    Rask, Anne Merete; Larsen, S.U.; Andreasen, Christian

    2013-01-01

    Many public authorities rely on the use of non-chemical weed control methods, due to stringent restrictions on herbicide use in urban areas. However, these methods usually require more repeated treatments than chemical weed management, resulting in increased costs of weed management. In order...... of treatments per year were required: glyphosate 2.5, hot water 3, flames 5, hot air/flames 5.5 and steam 5.5 treatments. The results demonstrate that the weed control should be adjusted to the prescribed quality for the traffic islands by regularly assessing the need for weed control. They also show...... to investigate the efficacy of four non-chemical weed control methods and glyphosate treatment, experiments were carried out on traffic islands in the growing seasons 2005 and 2006. Three trial sites were each divided into six treatment areas, which were either treated with glyphosate, flame, steam, hot air...

  1. Suicidal germination for parasitic weed control.

    Science.gov (United States)

    Zwanenburg, Binne; Mwakaboko, Alinanuswe S; Kannan, Chinnaswamy

    2016-11-01

    Parasitic weeds of the genera Striga and Orobanche spp. cause severe yield losses in agriculture, especially in developing countries and the Mediterranean. Seeds of these weeds germinate by a chemical signal exuded by the roots of host plants. The radicle thus produced attaches to the root of the host plant, which can then supply nutrients to the parasite. There is an urgent need to control these weeds to ensure better agricultural production. The naturally occurring chemical signals are strigolactones (SLs), e.g. strigol and orobanchol. One option to control these weeds involves the use of SLs as suicidal germination agents, where germination takes place in the absence of a host. Owing to the lack of nutrients, the germinated seeds will die. The structure of natural SLs is too complex to allow multigram synthesis. Therefore, SL analogues are developed for this purpose. Examples are GR24 and Nijmegen-1. In this paper, the SL analogues Nijmegen-1 and Nijmegen-1 Me were applied in the field as suicidal germination agents. Both SL analogues were formulated using an appropriate EC-approved emulsifier (polyoxyethylene sorbitol hexaoleate) and applied to tobacco (Nicotiana tabacum L.) fields infested by Orobanche ramosa L. (hemp broomrape), following a strict protocol. Four out of 12 trials showed a reduction in broomrape of ≥95%, two trials were negative, two showed a moderate result, one was unclear and in three cases there was no Orobanche problem in the year of the trials. The trial plots were ca 2000 m 2 ; half of that area was treated with stimulant emulsion, the other half was not treated. The optimal amount of stimulant was 6.25 g ha -1 . A preconditioning prior to the treatment was a prerequisite for a successful trial. In conclusion, the suicidal germination approach to reducing O. ramosa in tobacco fields using formulated SL analogues was successful. Two other options for weed control are discussed: deactivation of stimulants prior to action and

  2. THE EFFECT OF WINTER CATCH CROPS ON WEED INFESTATION IN SWEET CORN DEPENDING ON THE WEED CONTROL METHODS

    Directory of Open Access Journals (Sweden)

    Robert Rosa

    2015-02-01

    Full Text Available An experiment was carried out in east-central Poland (52°06’ N, 22°55’ E over 2008–2011 to study the effect of winter catch crops on the weed infestation, number, and fresh matter of weeds in sweet corn (Zea mays L. var. saccharata. The following winter catch crops were grown: hairy vetch (Vicia villosa Roth., white clover (Trifolium repens L., winter rye (Secale cereale L., Italian ryegrass (Lolium multiflorum L. and winter turnip rape (Brassica rapa var. typica Posp.. The catch crops were sown in early September and incorporated in early May. The effect of the catch crops was compared to the effect of FYM (30 t·ha-1 and control without organic manuring (NOM. Three methods of weed control were used: HW – hand weeding, twice during the growing period, GCM – the herbicide Guardian Complete Mix 664 SE, immediately after sowing of corn seeds, Z+T – a mixture of the herbicides Zeagran 340 SE and Titus 25 WG applied at the 3–4-leaf stage of sweet corn growth. Rye and turnip rape catch crops had least weeds in their fresh matter. Sweet corn following winter catch crops was less infested by weeds than corn following farmyard manure and non-manured corn. Least weeds and their lowest weight were found after SC, BRT and VV. LM and BRT reduced weed species numbers compared with FYM and NOM. The greatest weed species diversity, determined at the corn flowering stage, was determined after SC and FYM. The number and weight of weeds were significantly lower when chemically controlled compared with hand weeding. The best results were observed after a post-emergent application of the mixture Z+T. The weed species diversity on Z+T-treated plots was clearly lower compared with GCM and HW.

  3. Eficácia de herbicidas no controle de plantas daninhas na cultura da cebola em semeadura direta Efficacy of herbicides on weed control in onion direct sowing

    Directory of Open Access Journals (Sweden)

    Lino R. Ferreira

    1999-04-01

    Full Text Available As plantas de cebola provenientes da semeadura direta no campo são mais danificadas pelo cultivo mecânico e são mais sensíveis aos herbicidas, principalmente os latifolicidas, do que quando transplantadas. Com o objetivo de avaliar a eficácia dos herbicidas oxyfluorfen, ioxynil-octanoato e fluazifop-p-butil, aplicados em pós-emergência, isoladamente ou em mistura no tanque, com ou sem aplicação de paraquat, antes da emergência das plantas de cebola, conduziu-se este trabalho no município de Monte Alto, SP. Nenhum dos herbicidas aplicados isoladamente foi eficiente no controle de todas as espécies daninhas presentes na área experimental. As misturas no tanque de fluazifop-p-butil com oxyfluorfen ou ioxynil-octanoato, independente da aplicação ou não de paraquat aos cinco dias após a semeadura, controlaram eficientemente Portulaca oleracea, Amaranthus lividus, Echinochloa crusgalli, Eragrostis pilosa, Digitaria horizontalis, Eleusine indica e Brachiaria plantaginea, com produção de bulbos semelhante à da testemunha capinada.Onion plants, from direct sowing to the field, are more damaged by mechanical cultivation and more sensitive to herbicides, especially to broadleaf herbicides, than transplanted onions. With the purpose of evaluating the efficacy of the herbicides oxyfluorfen, ioxynyl-octanoato and fluazifop-p-butyl, applied in post-emergence, alone or tank mix, with or without paraquat application, before onion plants emergence, this investigation was carried out at Monte Alto County, São Paulo State, Brazil. None of the herbicides sprayed alone were efficient in the control of all the weeds present in the experimental area. The tank mix of fluazifop-p-butyl plus oxyfluorfen or ioxynyl-octanoato, regardless of paraquat application, at five days after sowing, controlled efficiently Portulaca oleracea, Amaranthus lividus, Echinoclhoa crusgalli, Eragrostis pilosa, Digitaria horizontalis, Eleusine indica and Brachiaria

  4. Crystal-associated cholangiopathy in sheep grazing Brachiaria decumbens containing the saponin protodioscin Colangiopatia associada a cristais em ovinos alimentados com Brachiaria decumbens que contém a saponina protodioscina

    Directory of Open Access Journals (Sweden)

    Karine B. Brum

    2007-01-01

    Full Text Available An outbreak of hepatogenous photosensitization is reported in a flock of 28 sheep grazing Brachiaria decumbens in Mato Grosso do Sul State, Central-Western Brazil. Seven lambs and an adult sheep were affected and 6 of them died. Two surviving affected lambs and one lamb without clinical signs had increased serum values of gamma glutamyltransferase, bilirubin, and cholesterol. In two adult unaffected sheep those parameters were within normal values. An adult sheep submitted to necropsy presented moderate body condition, unilateral corneal opacity, drying of the muzzle, moderate jaundice, increased lobular pattern of the liver, and a distended gallbladder. Histological lesions were epithelial degeneration, necrosis, and hyperplasia of small bile ducts. Mild amounts of foamy macrophages were observed, mainly in the centroacinar zone. Diffuse swelling and vacuolation were observed in hepatocytes. Crystal negative images were found within bile ducts, foamy macrophages, and the lumen of some renal tubules. The heart showed multifocal areas of degeneration and necrosis of the muscle fibers. Pasture samples (Brachiaria decumbens contained 2.36% of protodioscin. No Pithomyces chartarum spores were found in the pasture. Samples from a similar neighboring B. decumbens pasture grazed by cattle without photosensitization contained 1.63% of protodioscin isomers. Outbreaks of photosensitization caused by Brachiaria spp. are common in cattle in the Brazilian Cerrado (savanna with about 51 million hectares of Brachiaria spp pastures. Sheep farming has been recently developed in this region, and the number of sheep is increasing significantly. Because sheep are more susceptible than cattle to lithogenic saponins, poisoning by Brachiaria should be an important limiting factor for the sheep industry.Um surto de fotossensibilização hepatógena é descrito em um rebanho de 28 ovinos mantidos em pastagem de Brachiaria decumbens no Estado de Mato Grosso do Sul, regi

  5. Weed-cover versus weed-removal management in olive orchards: influence on the carbon balance at the ecosystem scale

    Science.gov (United States)

    Chamizo, Sonia; Serrano-Ortiz, Penélope; Vicente-Vicente, José Luis; Sánchez-Cañete, Enrique P.; López-Ballesteros, Ana; Kowalski, Andrew S.

    2016-04-01

    Agriculture plays an important role in the C budget at the global scale. Traditional practices based on soil tillage and applying herbicides to remove weeds have caused damage to soils and led to important losses of soil organic C and increased CO2 emissions to the atmosphere. Changing trends from traditional agriculture to conservation agriculture practices may have an important role in both C and water budgets and the transformation of agriculture from C source to C sink. The objective of this study was to analyse the effect of two treatments, weed removal by herbicides versus weed cover conservation, on the C balance in an irrigated olive orchard in SE Spain. Measurements of CO2 exchange were made from October 2014 to September 2015 using two eddy covariance towers, one for each olive crop treatment. Results show that CO2 fluxes at the ecosystem scale were similar in the two treatments during initial conditions, prior to weed growth in the soils without herbicide application (October). During the first week, daily net ecosystem exchange (NEE) was close to zero in both treatments, with values ranging from 1.06 to -0.41 g C m-2 in the weed cover treatment, and from 0.76 to -0.69 g C m-2 in the weed removal treatment. As weed growth increased, higher net CO2 assimilation was found in the treatment with weed cover. In both treatments, maximum net CO2 assimilation was found in March, with a monthly NEE of -72 and -28 g C m-2 in the treatment with and without weed cover, respectively. In May, after the weeds were cut and left on the soil, a strong increase was observed in NEE in the treatment with weed cover due to decreased CO2 assimilation and increased respiration compared to the treatment without weed cover. Therefore, soil chamber measurements showed average respiration rates of 2.57 and 1.57 μmol m-2 s-2 in the weed cover and weed removal treatment, respectively. Finally, the highest monthly NEE was registered during July, with both treatments showing a similar

  6. Crescimento de espécies do gênero Brachiaria sob alagamento em casa de vegetação Effect of flooding on the growth of Brachiaria species in greenhouse

    Directory of Open Access Journals (Sweden)

    Jorge Luiz Schirmer de Mattos

    2005-06-01

    Full Text Available Objetivou-se avaliar a tolerância ao alagameto de quatro espécies de Brachiaria (B. decumbens,B. brizantha, B. humidicola e B. mutica, a partir de suas características morfogênicas, fisiológicas e produtivas. Os tratamentos foram arranjados segundo esquema fatorial 4 x 3 quatro espécies de Brachiaria e três níveis de disponibilidade de água no solo (capacidade de campo, lâmina d'água de 1 e 10 cm acima do solo. O delineamento experimental foi de blocos completos ao acaso, com três repetições. O experimento foi instalado em casa de vegetação, utilizando-se colunas de PVC com 60 cm de altura x 30 cm de diâmetro. Os níveis de alagamento foram impostos a partir do 22º dia de rebrota após corte de uniformização. O acréscimo de água aos vasos, necessário para satisfazer a lâmina d'água a 1 e 10 cm do nível do solo nos respectivos vasos, foi controlado com o auxílio de furos presentes nas paredes dos vasos a 1 e 10 cm acima do nível do solo, respectivamente. O alagamento comprometeu a taxa de alongamento e acentuou a taxa de senescência das lâminas foliares, independentemente da espécie. Observou-se controle estomático das trocas gasosas em folhas de todas as espécies. O alagamento reduziu a fotossíntese líquida das espécies de Brachiaria, exceto de B. mutica, que superou as demais espécies sob a lâmina d'água de 10 cm acima do solo. Também diminuiu significativamente a área e o peso das lâminas foliares verdes, exceto em B. mutica, que apresentou apenas ligeira tendência de queda. A B. muticaapresentou numerosas raízes adventícias, que, possivelmente, lhe conferiram superior tolerância ao alagamento.This study aimed to evaluate the tolerance of four Brachiaria species (B. decumbens,B. brizantha, B. humidicola and B. mutica to flooding with regard to their morphogenetical, physiological and production characteristics. The experimental treatments resulted from a 4 x 3 factorial arrangement of four

  7. Seletividade e controle de plantas daninhas com oxyfluorfen e sulfentrazone na implantação de lavoura de café Weed selectivity and control with oxyfluorfen and sulfentrazone in young arabica coffee plantations

    Directory of Open Access Journals (Sweden)

    C.E.O. Magalhães

    2012-09-01

    Full Text Available Este trabalho teve por objetivo avaliar a seletividade do oxyfluorfen e do sulfentrazone e o controle de plantas daninhas em diferentes épocas após o transplantio das mudas de café no campo. Foram realizados três ensaios no delineamento experimental de blocos casualizados com dez tratamentos e quatro repetições. No ensaio 1, aos 30 dias após o transplantio (DAT e, no ensaio 2, aos 90 DAT, testaram-se duas doses de oxyfluorfen (0,36 e 0,72 kg i.a. ha-1 e de sulfentrazone (0,4 e 0,6 kg i.a. ha-1, em jato dirigido ao solo (com proteção das mudas e em área total. No ensaio 3, os mesmos herbicidas e doses foram aplicados, porém aos 300 DAT e apenas em aplicação dirigida, testando-se duas pontas de pulverização de diferentes potenciais de deriva. Em todos os ensaios, acrescentaram-se as testemunhas capinada e sem capina. A entrelinha foi manejada com roçada. Foram identificadas as espécies de plantas daninhas e suas densidades. A eficácia dos herbicidas e suas seletividades também foram avaliadas. A principal planta daninha que ocorreu na área experimental foi Brachiaria decumbens. Sintomas visuais de toxicidade foram observados apenas quando os herbicidas foram aplicados em área total (ensaios 1 e 2, independentemente da dose e época de aplicação. No ensaio 3, independentemente do herbicida, da dose e da ponta utilizada, não houve sintomas visuais de toxicidade, nem redução no crescimento das plantas, em função da aplicação dirigida. Em todas as épocas o controle de plantas daninhas foi eficiente, porém a seletividade só foi alcançada na aplicação dirigida, para ambos os herbicidas.This study aimed to evaluate oxyfluorfen and sulfentrazone selectivity and weed control in young coffee plantations (Coffea arabica cv. Red Catuaí. Three trials were conducted in a randomized complete block design, with 10 treatments and four replicates. In the first and second trials, at 30 and 90 days after transplanting (DAT

  8. Analysis of the Heterogeneity of Weed Infestation in Cereal Stands

    Directory of Open Access Journals (Sweden)

    Jan Winkler

    2015-01-01

    Full Text Available The aim of this study was to evaluate the heterogeneity of the incidence of individual weed species on a selected experimental field. This field was situated in the cadastre of the village Žabčice (South Moravian Region, Czech Republic. To evaluate the intensity of weed infestation, a field experiment was established. In 2011, altogether 33 weed species were identified in a stand of spring barley. In the next year, the total number of weeds in a stand of winter wheat was 22. Basing on results of the evaluation of infestation heterogeneity it was possible to detect the following trends: The first one concerned the incidence of significantly dominant species Chenopodium album and Veronica hederifolia in stands of spring barley and winter wheat, respectively. The second one expressed the incidence of the so-called sub-dominant species. Regarding the character of the incidence of these weed species it would be suitable to kill them by means of a targeted application of herbicides. Finally, the third trend concerned the incidence of that group of weeds that occurred in the major part of the experimental plot but in low numbers only. The abundance of these species was minimal and the total number of weed plants did not exceed the limit of 100 specimens. This group of weeds involved also those species that were markedly more frequent on plots situated closer to the margin of the experimental field. The targeted application of herbicides can be performed on plots with a lower level of weed infestation; another possibility, however, seems to be a targeted intervention that helps to control the incidence of a certain weed species and/or that is performed along the margin of the field where the different weed species are more frequent.

  9. Estrutura do capim-braquiária em relação à planta daninha - doi: 10.4025/actascianimsci.v33i3.10439 Structure of signalgrass in relation to weeds - doi: 10.4025/actascianimsci.v33i3.10439

    Directory of Open Access Journals (Sweden)

    Guilherme Portes Silva

    2011-06-01

    Full Text Available O objetivo foi avaliar as características estruturais da Brachiaria decumbens cv. Basilisk em relação à planta daninha Solanum sisymbrifolium no pasto. Os tratamentos foram dois locais no mesmo pasto, quais sejam, próximo e distante da planta daninha. O delineamento foi em blocos ao acaso com três repetições. O pasto foi manejado sob lotação contínua, com bovinos e com altura média de aproximadamente 25 cm. Foram quantificadas as densidades populacionais das categorias de tamanho dos perfilhos, a altura, a interceptação de luz, as massas e as densidades volumétricas dos componentes morfológicos do pasto. No local distante da planta daninha houve maior ocorrência de perfilhos com tamanho inferior a 20 cm. Já no local próximo da planta daninha, predominaram perfilhos com tamanho superior a 40 cm. A presença da planta daninha ocasionou aumento na altura do pasto e incremento na interceptação de luz pelo dossel. As massas e as densidades volumétricas de lâmina foliar viva, colmo vivo e material morto foram inferiores no local próximo da planta daninha em relação ao local distante. A ocorrência da planta S. sisymbrifolium provoca variabilidade espacial da vegetação no pasto de B. decumbens manejado sob lotação contínua com bovinos.The objective of this study was to evaluate the structural characteristics of Brachiaria decumbens cv. Basilisk in relation to Solanum sisymbrifolium in pasture. The treatments were two sites in the same pasture, near and far from the weeds. A randomized block design with three replications was used. The pasture was managed under continuous stocking and grass height was kept at about 25cm. Densities were quantified for categories tiller size, height, light interception, masses and volumetric densities of morphological components of the pasture. In the site far from the weeds there is a higher occurrence of tillers with size smaller than 20 cm. In site near the weeds, tillers larger than 40

  10. Interferência de plantas daninhas sobre o crescimento inicial de Coffea arabica Weed effect on the initial growth of Coffea arabica

    Directory of Open Access Journals (Sweden)

    C.M.T. Fialho

    2011-03-01

    Full Text Available Objetivou-se com este trabalho avaliar os efeitos da interferência de plantas daninhas, em diferentes densidades de infestação, sobre o crescimento de plantas jovens de café arábica. Mudas de café, cultivar Mundo Novo, foram transplantadas, no estádio de quatro a cinco pares de folhas completamente expandidas, para vasos com capacidade de 25 dm³. O experimento foi conduzido em casa de vegetação em blocos casualizados, em esquema fatorial (4 x 4; o primeiro fator foi composto por espécies de plantas daninhas (Digitaria horizontalis, Brachiaria decumbens, Brachiaria plantaginea e Mucuna aterrima, e o segundo, por densidades dessas espécies (zero, dois, quatro e seis plantas por vaso, com quatro repetições. O plantio das espécies daninhas foi realizado 60 dias após o transplantio do café (0 DAT. Nesta data e no dia do encerramento do experimento, aos 90 DAT, determinaram-se a altura, a área foliar e o diâmetro do caule da planta de café, para cálculo do incremento dessas variáveis. Aos 90 DAT, determinou-se a matéria seca da parte aérea e radicular do café e das plantas daninhas e a densidade radicular do café. Utilizando esses resultados, estimou-se a razão de massa foliar, razão de massa caulinar, razão de massa radicular, razão de área foliar e a razão sistema radicular/parte aérea das plantas de café. A espécie M. aterrima foi a que mais reduziu a taxa de crescimento, a área foliar, a matéria seca do caule e das folhas e o diâmetro do caule do café. Entre as gramíneas, B. plantaginea foi a que mais reduziu a taxa de crescimento, área foliar, diâmetro do caule e densidade radicular do café. Ocorreu relação negativa entre a densidade de plantas daninhas e as variáveis de crescimento e com a razão de massa radicular e razão sistema radicular/parte aérea.The goal of this work was to evaluate the effects of weeds on the growth of young Arabica coffee plants, at different densities of infestation

  11. Effect of weed control treatments and cutting frequency on weed dry ...

    African Journals Online (AJOL)

    Two experiments were conducted during the rainy seasons of 2012 and 2013 at the Teaching and Research Farm of the Department of Crop Science, University of Nigeria, Nsukka, to evaluate the growth and leaf yield of Telfairia occidentials Hook F. as influenced by weed control treatments and cutting frequencies.

  12. Designing, modeling and controlling a novel autonomous laser weeding system

    DEFF Research Database (Denmark)

    Shahrak Nadimi, Esmaeil; Andersson, Kim Johan; Jørgensen, Rasmus Nyholm

    2009-01-01

      Abstract: in this paper, the process of designing and developing a novel laser weeding test setup is explained. The main purpose of designing this system was to simulate the dynamic field conditions of a mobile vehicle capable of targeting weeds. This system consists of a rig containing three...

  13. Distribution patterns of segetal weeds of cereal crops in tajikistan

    International Nuclear Information System (INIS)

    Nowak, A.; Nowak, S.

    2015-01-01

    Using the literature data and field research conducted in 2009-2013 the distribution patterns, habitat conditions, phytogeographical characterisation and endangerment of weeds occurring in cereal crops in Tajikistan were analysed. We found out that Tajik weed flora of cereal crops counts 686 taxa. The most species rich families include Asteraceae, Poaceae and Fabaceae. The highest number of cereal weeds were noted in large river valleys of Syr-Daria, Amu-Daria and their tributaries in south-western and northern Tajikistan. This subregions have the warmest climate conditions and extensive arable lands. The greatest weed species richness was observed in submontane and montane elevations between approx. 700 and 1,900 m a.s. Cereal weeds occur frequently outside segetal communities in Tajikistan. They were noted usually in screes, wastelands, xerothermophilous grasslands, river gravel beds and in steppes habitats. The assessment of threat status reveals that ca. 33% of total cereal weed flora in Tajikistan are disappearing or occur very rarely. According to the chorological data we find that in the cereals of Tajikistan, 35 endemic and 14 subendemic species occur. The most numerous chorological elements of threatened weed flora of Tajikistan are Irano-Turanian (55%), pluriregional (16%), cosmopolitan (14,5%), Mediterranean (9%) and Eurosiberian (5%) species. Further research is suggested to explore the distribution patterns of all weed species in Tajikistan as it should be useful for economy and effectiveness of crop production as well as conservation of most valuable species. (author)

  14. Effect of different weed management techniques on growth ...

    African Journals Online (AJOL)

    The weed management techniques included slashing at 8-weekly intervals, mulching alone, glyphosate + slashing, glyphosate + mulching, glyphosate alone and a weed-free control. Glyphosate + mulching proved to have the greatest positive influence on plant height, plant girth, leaf area and number of leaves throughout ...

  15. Aquatic weed control within an integrated water management framework

    NARCIS (Netherlands)

    Querner, E.P.

    1993-01-01

    Aquatic weed control, carried out by the water boards in the Netherlands, is required to maintain sufficient discharge capacity of the surface water system. Weed control affects the conditions of both surface water and groundwater. The physically based model MOGROW was developed to simulate

  16. How to Identify and Control Water Weeds and Algae.

    Science.gov (United States)

    Applied Biochemists, Inc., Mequon, WI.

    Included in this guide to water management are general descriptions of algae, toxic algae, weed problems in lakes, ponds, and canals, and general discussions of mechanical, biological and chemical control methods. In addition, pictures, descriptions, and recommended control methods are given for algae, 6 types of floating weeds, 18 types of…

  17. Evaluation of Selected Pre-Emergence Herbicides for Weed Control ...

    African Journals Online (AJOL)

    Pendimentalin had no significant effect on the plantlets across the rates tested. The best weed control was achieved with diuron applied at 25% and above, while the least weed control occurred on the control plot and these treated with 10% of atrazine and primextra Gold. However, there were no significant variations in the ...

  18. Weed management in banana production: The use of Nelsonia ...

    African Journals Online (AJOL)

    During a survey of weeds in the Tiko banana plantations, the plant Nelsonia canescens (Lam.) Spreng was found to have invaded large areas of the plantation with no visible adverse effects on the banana crop. The effects of this Acanthaceae on banana yield parameters, snails' population and weed species diversity and ...

  19. Effects of different crop associations and fertilizer types on weed ...

    African Journals Online (AJOL)

    Experiments were conducted at the Teaching and Research Farm of the University of Ibadan in 1998/1999 and 1999/2000 cropping seasons to determine the effects of different crop associations and fertilizer types on the weed biomass. The results showed that crop associations did not significantly affect weed density and ...

  20. Developing selection protocols for weed competitiveness in aerobic rice

    NARCIS (Netherlands)

    Zhao, D.L.; Atlin, G.N.; Bastiaans, L.; Spiertz, J.H.J.

    2006-01-01

    Aerobic rice production systems, wherein rice is dry-sown in non-puddled soil and grown as an upland crop, offer large water savings but are subject to severe weed infestation. Weed-competitive cultivars will be critical to the adoption of aerobic rice production by farmers. Breeding

  1. Critical Period for Weed Removal in Garden Egg (Solanum Incanum ...

    African Journals Online (AJOL)

    Field experiments were conducted at the Teaching and Research Farm, Adeyemi College of Education, Ondo during the 2004 and 2005 cropping seasons to determine the extent of yield loss due to weed infestation and the critical time for weed removal in garden egg (Solanum incanum). The experiment which was ...

  2. Efficacy of selected herbicide formulations on sugarcane field weeds ...

    African Journals Online (AJOL)

    In continuation for the search of appropriate weed control strategy for sugarcane field weeds at the Unilorin Sugar Research Institute (USRI), Ilorin located at 8o 030' N; 4o 32' E , Nigeria. Field trials were laid out in a randomized complete block design during 2012 and 2013 growing seasons to evaluate four herbicide ...

  3. Effect of weed management methods and nitrogen fertilizer rates on ...

    African Journals Online (AJOL)

    Inefficient weed management practices and the use of inappropriate nitrogen fertilizer rates are the major causes of low yield of wheat in Ethiopia. Therefore, field experiments were conducted at Bobicho and Faate in southern Ethiopia to determine the effect of weed management practices and N fertilizer rates on grain yield ...

  4. economics of herbicide weed management in wheat in ethiopia ...

    African Journals Online (AJOL)

    ACSS

    Effective use of herbicides for the control of annual grass and broadleaf weeds in wheat (Triticum aestivum L.) was not a reality in Ethiopia, until in recent years. This study aimed at evaluating different post-emergence herbicides against annual grasses and broadleaf weeds in wheat for selection and incorporation into an ...

  5. Effect Of Weed On Oil Palm Inflorenscence Production: Implication ...

    African Journals Online (AJOL)

    Weed consistently depressed the performance of oil palm and this depressive effect was attributed to aggressive growth resources, smothering of the oil palm and preventing the palm from proper ventilation and solar radiation. Weed interference on inflorescence production of oil palm was assessed with the view of ...

  6. effect of fluazitopbutyl and atrazine/metolachlor for weed control

    African Journals Online (AJOL)

    COCOYAM

    also gave the highest yield and monetary gain when compares with manual weeding. This technique will be ... be a “back yard” crop or “gap filler”. Survey reports in .... Critical period of weed interference intercropped with maize and cocoyam.

  7. An Autonomous Robotic System for Mapping Weeds in Fields

    DEFF Research Database (Denmark)

    Hansen, Karl Damkjær; Garcia Ruiz, Francisco Jose; Kazmi, Wajahat

    2013-01-01

    The ASETA project develops theory and methods for robotic agricultural systems. In ASETA, unmanned aircraft and unmanned ground vehicles are used to automate the task of identifying and removing weeds in sugar beet fields. The framework for a working automatic robotic weeding system is presented...

  8. WEED FLORA OF CASSAVA IN WEST NILE ZONES OF UGANDA ...

    African Journals Online (AJOL)

    ACSS

    Information on weeds of cassava (Manihot esculenta Crantz) in eastern Africa is limited. The objective of this study was to establish the status of weed flora in selected cassava growing regions of Uganda. This study was conducted in 2013 at Abi Zonal Agricultural Research and Development Institute; (AbiZARDI) in Arua, ...

  9. UAV low-altitude remote sensing for precision weed management

    Science.gov (United States)

    Precision weed management, an application of precision agriculture, accounts for within-field variability of weed infestation and herbicide damage. Unmanned aerial vehicles (UAVs) provide a unique platform for remote sensing of field crops. They are more efficient and flexible than manned agricultur...

  10. A weed suppressive index for spring barley (Hordeum vulgare) varieties

    DEFF Research Database (Denmark)

    Hansen, P K; Kristensen, K; Willas, J

    2008-01-01

    A screening programme for crop variety competitiveness would ideally be based on only a few, non-destructive measurements of key growth traits. In this study we measured the weed suppressive ability of 79 varieties of spring barley in two ways: (i) directly, by weed coverage assessments under wee...

  11. Optimal weed management in crop rotations: incorporating economics is crucial

    NARCIS (Netherlands)

    Berg, van den F.; Gilligan, C.A.; Lemmen-Gerdessen, van J.C.; Gregoire, L.A.H.; Bosch, van den F.

    2010-01-01

    Although the effects of crop rotation sequence and length on weed population dynamics have been studied, it is not clear whether or not the best strategy, from a weed population dynamics point of view, is also the economic optimal strategy. It is also not clear which biological and economic

  12. Big Data for weed control and crop protection

    NARCIS (Netherlands)

    Evert, van F.K.; Fountas, S.; Jakovetic, D.; Crnojevic, V.; Travlos, I.; Kempenaar, C.

    2017-01-01

    Farmers have access to many data-intensive technologies to help them monitor and control weeds and pests. Data collection, data modelling and analysis, and data sharing have become core challenges in weed control and crop protection. We review the challenges and opportunities of Big Data in

  13. Cover crop residue management for optimizing weed control

    NARCIS (Netherlands)

    Kruidhof, H.M.; Bastiaans, L.; Kropff, M.J.

    2009-01-01

    Although residue management seems a key factor in residue-mediated weed suppression, very few studies have systematically compared the influence of different residue management strategies on the establishment of crop and weed species. We evaluated the effect of several methods of pre-treatment and

  14. Weed biocontrol in the EU: from serendipity to strategy

    Science.gov (United States)

    Biological control of weeds is a globally-recognized approach to the management of the worst invasive plants in the world. Unfortunately, accidental introduction of agents account for most weed biocontrol in the EU, but do include a number of current or emerging successes. From the redistribution of...

  15. Managing invasive plants in natural areas: Moving beyond weed control

    Science.gov (United States)

    Dean Pearson; Yvette Ortega

    2009-01-01

    Exotic invasive plants present one of the greatest challenges to natural resource management. These weeds can alter entire communities and ecosystems, substantially degrading important ecosystem services such as forage for wild and domestic herbivores, water and soil quality, recreational values, and wildlife habitat. Traditionally, weed management in natural areas has...

  16. Induced mutation studies with Brachiaria brizantha Stapf. and some indica rice varieties from Ceylon

    Energy Technology Data Exchange (ETDEWEB)

    Ganashan, P [Agricultural Research Station, Maha-Illuppallama, Ceylon (Sri Lanka)

    1970-03-01

    Non-imbibed seeds of Brachiaria brizantha were irradiated with doses of {sup 60}Co gamma rays ranging from 7.5 to 75 kR and fresh stem cuttings containing three nodes were irradiated with doses ranging from 7.5 to 45 kR. Chromosome counts were made using the Carnoy method. There was no germination at 75 kR, and 18% germination at 60 kR with no survival of the seedlings. At the other doses germination and seedling survival decreased from 56% and 100% respectively for the control to 42% and 46% respectively at 45 kR. There were no chlorophyll mutants at 7.5 kR, while a few were observed among seedlings at the higher doses. In the stem cuttings establishment was poor and morphological variations were observed at all doses above 15 kR. A mutant of desirable plant type was obtained from the 45-kR seed treatment with an erect growth habit, reduced pubescence, short internodes, profuse tillering and rapid regrowth compared with the parent. Four indica rice varieties, H-4, H-8, H-7 and Pachchaiperumal 2462/11 (PP 2462/11), were subjected to gamma rays, neutrons and ethyl methane sulphonate (EMS) treatments. The LD{sub 50} level for gamma rays was 50 to 60 kR, for neutrons 1600 R and for EMS 0.4%. Germination and final plant stand in the M{sub 1} generation were affected only slightly by the neutron treatments, but were greatly reduced by EMS, and gamma irradiation above 35 kR. The final plant stand of the variety PP 2462/11 was most reduced by all the mutagens. In the M{sub 2} generation there was segregation for chlorophyll mutants, of the albina, chlorina, xantha, virescens and zebrina types. Other macro-mutations observed were for grain size and shape, plant height, flowering date and sterility. Grass clump types were found occasionally. (author)

  17. Chlorophyll evaluation methods in Brachiaria brizantha brs Piatã added with poultry litter compost

    Directory of Open Access Journals (Sweden)

    Alexandre Antonio Pasqualini

    2013-12-01

    Full Text Available One of the major limitations for pastures high production is the low fertility of tropical soils. In general, the nutrient reposition through chemical fertilizers increases the cost of production and can unbalance the plant besides the environment pollution. Recycling solid residues from agribusiness is a sustainable alternative for farmers. Among the residues, the poultry litter (PL aerobically fermented is a very good bio fertilizer for pastures. The Piatã Grass (Brachiaria brizantha is a new option for the pasture market and can be used for bovine, equine or ovine. The fast diagnosis of the nutritional stage of this plant, based upon portable methods as the Dualex, measuring leaf light reflectance is a practical alternative.  By this way,  it is possible to offer to the herd high nutritional food, correcting eventual shortage, mainly nitrogen. Nitrogen nutrition is directely related to chlorophyll content in the leaf blade. This study aimed to verify the effects of doses of PL over total chlorophyll, in comparison to two methods of evaluation: Dualex Scientific 4.0 and Spectrophotometer Analysis according to Lichtenthaler & Wellburn (1983. The experiment was conducted in greenhouse conditions, at IZ, Nova Odessa, with a Haplortox soil, between May and July, 2013. Treatments consisted of five compost doses (PL: 0, 20, 40, 60 and 120 Mg ha-1, with the following chemical composition (%: 2.88 of N, 3.85 of P2O5, 2.50 of K2O, 9.06 of Ca and 1.16 of Mg. The experimental design was on randomized blocks with five replications. Data were analyzed using the GLM procedure of the SAS program. Chlorophyll data were taken from the third medium of the leaf blade from a third of the expanded leaf from the apical using the Dualex. At the same time, samples were harvested for the Spectrophotometer analyses according to methodology described by Lichtenthaler & Wellburn (1983. Total Chlorophyll amounts were increased with the higher doses of PL, adjusting

  18. Ruminal degradation kinetic of Brachiaria decumbens silages with different nitrogen additives

    Directory of Open Access Journals (Sweden)

    Odimári Pricila Pires do Prado

    2014-02-01

    Full Text Available This study aimed to assess levels of nitrogen additive Silogen® pasto on ruminal in vitro degradability gas production in Brachiaria decumbens silages. The nitrogen additive contained bacterial strains (Bacillus subtilis, Lactobacillus curvatus, Lactobacillus plantarum and Pediococcus acidilactici and minimum nitrogen to 360 g/kg. The levels were: 0.0; 1.0; 1.5; 2.0 and 2.5%. In fractionation were calculated total carbohydrates (TC, non-fiber carbohydrates (NFC, soluble and rapidly degradable (A + B1, potentially degradable (B2 and degradable (C. The kinetic parameters of FC and NFC were estimated using the technique of in vitro gas production. Data were subjected to analysis of variance at 5%. The level additive did not influence the TC and fraction A + B1. The levels of nitrogen additive influenced the NFC, fractions B2 and C. For NFC content 2.0% showed the lowest (22.0 %. The lower levels of additive nitrogen (0, 1.0 and 1.5 % had higher fractions of B2 (average 40.2 % and lower values for the fraction C (average 20.0 % . There was no difference in the volume of gas CNF (average 86.73 mL and final volume of gas produced (average 195.79 mL. Was no influence of nitrogen additives for the time of colonization, the lowest time of 3.89 h to 1.0%. The volume of gas of FC was influenced by levels of nitrogen additives with higher values to 0 % from 1.0 %, and 114.74 and 115.09 mL, respectively. Degradation rates of FC and FNC were also affected by the concentrations of nitrogenous additives, which presented higher rates to the levels of 2.0 and 2.5%. It follows that the lower levels of additives to 1.5 % promoted the reduction of the C fraction and increased B2, and greater production of gas volume of the fiber in these silages, showing better nutritional value in these silages.

  19. Allelopathic evidence in Brachiaria decumbens and its potential to invade the Brazilian Cerrados

    Directory of Open Access Journals (Sweden)

    Elizabeth Gorgone Barbosa

    2008-08-01

    Full Text Available The aim of this study was to look for evidence of allelochemicals in B. decumbens, in parts of the plant from where they could easily be released to the environment. The germination inhibition of Phalaris canariensis, Lactuca sativa (standard species and Melinis minutiflora, another invasive African grass, was tested using B. decumbens germinating seeds and aqueous leachates of the roots, green and senescent leaves, at 5, 10 and 20% w/v. Both the germinating seeds and the aqueous leachates of B. decumbens reduced the germination of the species tested; the effectiveness of the aqueous leachates increased according to concentration. Apparently, the competitive advantage of B. decumbens in the cerrados could be amplified via allelopathy.Invasão biológica é uma das maiores causas atuais da perda de biodiversidade. Várias espécies que se tornam invasoras produzem substâncias fitotóxicas que aumentam sua capacidade competitiva; assim, a alelopatia é uma estratégia capaz de potencializar o sucesso de invasão. Brachiaria decumbens, uma gramínea africana, invadiu os cerrados brasileiros e representa, atualmente, uma séria ameaça à biota regional. Neste ensaio, verificamos a presença de aleloquímicos em partes de B. decumbens das quais poderiam ser facilmente liberados para o ambiente. Testamos a inibição da germinação de Phalaris canariensis, Lactuca sativa (espécies padrão e Melinis minutiflora (outra gramínea africana invasora usando sementes de B. decumbens e soluções aquosas lixiviadas de suas raízes, folhas verdes e folhas senescentes, a 5, 10 e 20% de peso do material por volume de água. Tanto as sementes como as soluções lixiviadas de decumbens reduziram a germinação das outras espécies; a eficiência dos lixiviados aumentou de acordo com a concentração da solução. Acreditamos que a grande vantagem competitiva de B. decumbens no cerrado possa ser amplificada pela alelopatia.

  20. Effects of light intensity on growth, anatomy and forage quality of two tropical grasses (Brachiaria brizantha and Panicum maximum var. trichoglume).

    NARCIS (Netherlands)

    Deinum, B.; Sulastri, R.D.; Zeinab, M.H.J.; Maassen, A.

    1996-01-01

    Effects of light intensity on growth, histology and anatomy, and nutritive value were studied in seedlings of two shade tolerant species: Brachiaria brizantha and Panicum maximum var. trichoglume. They were studied under greenhouse conditions in pots with sandy soil and sufficient N and cut after a

  1. Team-up Crop Diversification and Weed Management: PRODIVA

    DEFF Research Database (Denmark)

    Gerowitt, B.; Melander, B.; Krawczyk, R.

    2015-01-01

    The research-network PRODIVA focuses on a better utilization of crop diversification for weed management in North European arable cropping systems. The goal is to maintain diverse arable weed vegetation that is manageable in the long-term and could fulfil other necessary systemfunctions including...... support of beneficial organisms. The partners in PRODIVA will synthesize knowledge from terminated and running research projects and set-up selected new experiments on cover crops and variety resp. crop mixtures. Moreover, we will interact with partners from farming practice and extension services...... in organic agriculture. Regional fields will be surveyed for weeds to safeguard the relevance of the experimental research. Current cropping practices and their influence on weed pressure and weed diversity will be identified. The project will involve relevant stakeholders from the participating countries...

  2. Weed Mapping with Co-Kriging Using Soil Properties

    DEFF Research Database (Denmark)

    Heisel, Torben; Ersbøll, Annette Kjær; Andreasen, Christian

    1999-01-01

    Our aim is to build reliable weed maps to control weeds in patches. Weed sampling is time consuming but there are some shortcuts. If an intensively sampled variable (e.g. soil property) can be used to improve estimation of a sparsely sampled variable (e.g. weed distribution), one can reduce weed...... sampling. The geostatistical estimation method co-kriging uses two or more sampled variables, which are correlated, to improve the estimation of one of the variables at locations where it was not sampled. We did an experiment on a 2.1 ha winter wheat field to compare co-kriging using soil properties......, with kriging based only on one variable. The results showed that co-kriging Lamium spp. from 96 0.25m2 sample plots ha-1 with silt content improved the prediction variance by 11% compared to kriging. With 51 or 18 sample plots ha-1 the prediction variance was improved by 21 and 15%....

  3. Allelopatic potential of weeds under the minimalization of soil treatment

    Directory of Open Access Journals (Sweden)

    Mikhail A. Mazirov

    2014-01-01

    Full Text Available The content of water-dispersible phenol substances in rhizosphere both of annual and perennial species of weeds (Cirsium arvense, Sonchus arvensis increases under soil treatment minimalization. The higher content of phenol substances of researched weeds is defined in rhizosphere of Common Couch (Agropyrum repens. The absence of intensive anthropogenic treatment of plowing layer which accumulates the significant mass of weed’s roots in the cause of much more higher allelopathic potential of some species’ of weeds. The high level of saturation by weeds in agrophytocoenosis under non-tillage soil treatment is defines the competitiveness between certain sepsis’ of weeds, especially, at the beginning of the vegetation. In this case, increasing the secretion of phenol substances is one of the physiological screenings of such competitiveness.

  4. Avaliação de fontes de urease na amonização de fenos de Brachiaria brizantha com dois teores de umidade Evaluation of urease sources in the ammoniation of Brachiaria brizantha hays with two moisture levels

    Directory of Open Access Journals (Sweden)

    Liandra Maria Abaker Bertipaglia

    2005-04-01

    Full Text Available O efeito da amonização com uréia (5,0% matéria seca do feno de Brachiaria brizantha, com dois teores de umidade (15 ou 30% de umidade, associado a três fontes de urease (feno de capim Brachiaria decumbens, capim-elefante [Pennisetum purpureum] e leucena [Leucaena leucocephala], foi avaliado. Foram determinados os teores de proteína bruta (PB, fração solúvel (A, frações de proteína verdadeira solúvel e insolúvel em borato fosfato (B1 e B2, fração de proteína potencialmente degradável (B3 e fração da proteína insolúvel em detergente ácido (C. Avaliaram-se os teores de fibra em detergente neutro (FDN, fibra em detergente ácido (FDA, celulose (CEL, hemicelulose (HEM e lignina (LIG e digestibilidade in vitro da matéria seca (DIVMS. O delineamento experimental foi o de blocos inteiramente casualizados, com 10 tratamentos (dois controles, 15 e 30% umidade, sem uréia e sem urease; dois controles, 15 e 30% umidade, com uréia e sem urease; seis combinações de fontes de urease e conteúdo de umidade e três repetições. A amonização dos fenos com diferentes conteúdos de umidade, associados a fontes de urease, aumentou os teores de PB e da fração A, mas não afetou B1 e B2. Contudo, as frações B3 e C diminuíram em reposta à amonização. A aplicação de uréia nos fenos de 30% de umidade, associados ou não a fontes de urease, diminuiu os teores de FDN. A adição de fontes de urease não alterou os teores dos constituintes da parede celular, quando comparada aos tratamentos amonizados com uréia. Os tratamentos aplicados não proporcionaram efeitos consistentes sobre os teores de FDA e de CEL dos fenos e não afetaram os teores de LIG. A aplicação de uréia associada a 15 ou 30% de umidade foi favorável para aumentar o nitrogênio solúvel do feno de Brachiaria brizantha e diminuir o nitrogênio indisponível para o ruminante.The urea ammoniation (5.0% dry matter effects in Brachiaria brizanta hay baled with two

  5. Distribuição mensal da emergência de seis ervas daninhas em solos com e sem cultivos Monthly emergence of six weeds in cultived and undisturbed soil

    Directory of Open Access Journals (Sweden)

    Hélio G. Blanco

    1994-01-01

    Full Text Available Foram realizados no período de 14 meses, com início em outubro de 1988, levantamentos demográficos mensais para registro da dinâmica de emergência de seis espécies de ervas daninhas anuais, submetidas mensalmente a um dos seguintes sistemas de manejo da população: grade de disco, grade de disco seguida de rolo compactador do solo, enxada rotativa, e herbicida de contato. Os resultados mostraram que a distribuição mensal da emergência de Digitaria horizontalis Willd. (capim-colchão, Brachiaria plantaginea (Link Hitch. (capim-marmelada, Bidens pilosa L. (picão-preto, e Amaranthus viridis L. (caruru-de-mancha, se configurou com um pico de emergência muito alto em outubro (acima de 80% do total emergido no período, com reinfestações pouco significativas nos meses seguintes, e que o manejo através do cultivo do solo favoreceu a emergência dessas espécies. O modelo de emergência de Eleusine indica (L. Gaertn. (capim-pé-de-galinha, e Eragrostis pilosa (L. Beauv. (capim-barba-de-alemão, por outro lado, apresentou um grau de emergência baixo em outubro, elevando-se até janeiro quando ocorreu o fluxo de maior pico. O manejo sem revolvimento do solo dessas duas espécies incrementou a geminação dos propágulos do banco de sementes. De um modo geral, quando não se permitiu a multiplicação sexuada, a taxa de população foi extremamente reduzida no ciclo seguinte.In lhe period of October/l988 to December/1989 a research was carried out to study lhe emergence dynamics of six weeds through monthly samplings under four weed managements: destruction of lhe former flora by cultivation with harrow, harrow following compaction by soil roller, rotary harrow and use of a contact herbicide without soil disturbance. The results showed that lhe initial emergence in October is very high for Digitaria horizontalis, Brachiaria plantaginea, Bidens pilosa and Amaranthus viridis compared with lhe emergence in lhe following months and that

  6. Períodos de interferência das plantas daninhas na cultura do arroz de terras altas. II - cultivar Caiapó Interference periods of weeds in the upland rice - Caiapó variety

    Directory of Open Access Journals (Sweden)

    Maria Rosangela Malheiros Silva

    2009-01-01

    Full Text Available Os experimentos foram desenvolvidos nos anos agrícolas 2003/2004 e 2004/2005, em área experimental da Universidade Estadual Paulista, Campus de Jaboticabal (SP, com o objetivo de se determinarem os períodos de interferência das plantas daninhas na cultura do arroz de terras altas, cultivar Caiapó. O delineamento experimental foi em blocos ao acaso com quatro repetições e 16 tratamentos. Os tratamentos foram constituídos por períodos crescentes de controle ou de convivência das plantas daninhas após a emergência da cultura: 0-10, 0-20, 0-30, 0-40, 0-50, 0-60, 0-70 dias e 0-colheita. Nos dois anos, as famílias predominantes eram Poaceae, Asteraceae, Amaranthaceae e Malvaceae e as principais plantas daninhas presentes foram: Cyperus rotundus L., Cenchrus echinatus L., Digitaria spp Heist., Echinochloa crus-galli (L. P. Beauv., Brachiaria decumbens Stapf., Eleusine indica Gaertn e Alternanthera tenella Colla. A cultivar de arroz de terras altas Caiapó deve ser mantida sem plantas daninhas nos 30 dias após a emergência.The experiments were carried out in two growing seasons (2003/04 and 2004/05 in an experimental area at São Paulo State University - UNESP, Jaboticabal Campus, to evaluate the weed interference periods on the upland Caiapó rice variety. The experimental design was randomized blocks with 4 replicates and 16 treatments. The treatments consisted of increasing periods of control or coexistence after emergence of the culture: 0-10; 0-20; 0-30; 0-40; 0-50; 0-60; 0-70 days; 0-harvest. The predominant families were Poaceae, Asteraceae, Amaranthaceae and Malvaceae, and the main weeds present were Cyperus rotundus L., Cenchrus echinatus L., Digitaria spp Heist., Echinochloa crus-galli (L. P. Beauv., Brachiaria decumbens Stapf., Eleusine indica Gaertn e Alternanthera tenella Colla for both years. The upland rice cultivar Caiapó is to be kept free of weeds for 30 days after emergence.

  7. Weed species diversity in organic and integrated farming systems

    Directory of Open Access Journals (Sweden)

    Magdalena Jastrzębska

    2013-10-01

    Full Text Available Phytosociological data were collected in 1994–1996 in plots (relevés at the Research Station for Organic Farming and Conservation Breeding of the Polish Academy of Sciences in Popielno included in a large-area experiment conducted according to the concept and method proposed by Prof. S. Nawrocki. In a four-field crop rotation (root crops – spring barley undersown with red clover and grasses – red clover/grass mixture – winter triticale, each field was divided into two management units, organic and integrated. Data were collected in relevés by the Braun-Blanquet method, each year at the peak of the growing season. Weed abundance (% cover in cultivated fields and the number of weed species (species richness in crops were determined, which provided a basis for calculating the Shannon-Wiener indices of species diversity and evenness, and the Rényi profiles. The qualitative (species and quantitative structure of weed communities was compared using the Sørensen index. A total of 115 weed taxa (species, subspecies and varieties were identified in the examined agro-phytocenoses. Echinochloa crus-galli, Chenopodium album, Matricaria maritima subsp. inodora, Capsella bursa-pastoris, Thlaspi arvense and Stellaria media were the most abundant. Weed infestation was slightly higher in the organic farming system than in the integrated system. Organic farming contributed to higher weed species diversity in root crops, red clover/grass mixtures and winter triticale. Weed species richness was reduced in red clover/grass stands, while root crops and – to a lesser degree – spring barley undersown with red clover and grasses decreased weed species diversity. The species composition and in particular the quantitative structure of weeds were affected by crop species and cultivation regime rather than by the farming system. Weed communities of crops grown under organic and integrated farming systems were more similar with regard to species composition

  8. RNAseq reveals weed-induced PIF3-like as a candidate target to manipulate weed stress response in soybean

    NARCIS (Netherlands)

    Horvath, David P; Hansen, Stephanie A; Moriles-Miller, Janet P; Pierik, Ronald; Yan, Changhui; Clay, David E; Scheffler, Brian; Clay, Sharon A

    Weeds reduce yield in soybeans (Glycine max) through incompletely defined mechanisms. The effects of weeds on the soybean transcriptome were evaluated in field conditions during four separate growing seasons. RNASeq data were collected from six biological samples of soybeans growing with or without

  9. Dinâmica do banco de sementes de plantas daninhas sob diferentes sistemas de manejo de solo Weed seedbank dynamics under different soil management systems

    Directory of Open Access Journals (Sweden)

    E. Voll

    2001-08-01

    Full Text Available Um experimento foi conduzido em campo no período de 1982 a 1998, em Londrina-PR, com o objetivo de avaliar o efeito de diferentes sistemas de manejo de solo nas reduções anuais de um banco de sementes de plantas daninhas e seus períodos de sobrevivência, sendo as plantas daninhas manejadas através de herbicidas, e a seqüência anual de cultivo soja após trigo. Os tratamentos de manejo de solos foram: 1 semeadura direta; 2 arado de discos e grade niveladora; 3 grade aradora e grade niveladora; 4 escarificação e grade niveladora. O delineamento experimental foi o de blocos ao acaso, com quatro repetições. A identificação e contagem das sementes presentes no solo foram feitas em 1990, 1995 e 1998. As estimativas de sobrevivência (a 1% da população inicial das gramíneas capim-marmelada (Brachiaria plantaginea e capim-colchão (Digitaria horizontalis , nos quatro sistemas de manejo, foram de 5 a 10 anos e 5 a 7 anos, respectivamente; as das espécies de folhas largas, como caruru (Amaranthus spp., de 5 a 9 anos, carrapicho-de-carneiro (Acanthospermum hispidum , de 7 a 9 anos, de 10 a 20 anos, e picão-preto (Bidens pilosa, de 3 a 4 anos, e a comelinácea trapoeraba (Commelina benghalensis de 10 a 20 anos. As sementes de espécies de plantas daninhas apresentaram características distintas de sobrevivência, em função do manejo do solo, do controle ao longo dos anos e das características morfológicas e fisiológicas das sementes.A field experiment was conducted from 1982 to 1998, in Londrina-PR, Brazil, to evaluate the effects of different soil management systems on the survival of a weed seedbank, with the weeds managed by herbicides, and the annual sequence of crops consisting of soybean - wheat. The soil management treatments were: 1 no-till; 2 mouldboard; 3 heavy disc, and 4 chisel. The experimental design was a randomized complete block, with four replications. Seed identification and counting were performed in 1990, 1995

  10. Accuracy of two optical chlorophyll meters in predicting chemical composition and in vitro ruminal organic matter degradability of Brachiaria hybrid, Megathyrsus maximus, and Paspalum atratum

    Directory of Open Access Journals (Sweden)

    Martin P. Hughes

    2017-03-01

    Full Text Available The objective of this study was to determine the accuracy and reliability of 2 optical chlorophyll meters: FieldScout CM 1,000 NDVI and Yara N-Tester, in predicting neutral detergent fibre (NDF, acid detergent fibre (ADF, acid detergent lignin (ADL, acid detergent insoluble nitrogen (ADIN and in vitro ruminal organic matter degradability (IVOMD of 3 tropical grasses. Optical chlorophyll measurements were taken at 3 stages (4, 8 and 12 weeks of regrowth in Brachiaria hybrid, and Megathyrsus maximus and at 6 and 12 weeks of regrowth in Paspalum atratum (cv. Ubon. Optical chlorophyll measurements showed the highest correlation (r = 0.57 to 0.85 with NDF concentration. The FieldScout CM 1,000 NDVI was better than the Yara N-Tester in predicting NDF (R2 = 0.70 and ADF (R2 = 0.79 concentrations in Brachiaria hybrid and NDF (R2 = 0.79 in M. maximus. Similarly, FieldScout CM 1,000 NDVI produced better estimates of 24 h IVOMD (IVOMD24h in Brachiaria hybrid (R2 = 0.81 and IVOMD48h in Brachiaria hybrid (R2 = 0.65 and M. maximus (R2 = 0.75. However, these prediction models had relatively low concordance correlation coefficients, i.e., CCC >0.90, but random errors were the main source of bias. It was, therefore, concluded that both optical chlorophyll meters were poor and unreliable predictors of ADIN and ADL concentrations. Overall, the FieldScout CM 1,000 NDVI shows potential to produce useful estimates of IVOMD24h and ADF in Brachiaria hybrid and IVOMD48h and NDF concentrations in M. maximus.

  11. Chemical weed control in barley (hordeum vulgare)

    International Nuclear Information System (INIS)

    Sarwar, M.; Hassan, S.W.; Abid, A.A.

    2008-01-01

    Effect of two different pre-emergence herbicides i.e. Terbutryn (lgron-500FW) A, 1.01.25 kg a.t. ha/sup -1/ and Flurochloridone (Racer-25 CS) a 0.31, 0.37, 0.44, 0.50 and 0.56 Kg a.i. ha/sup -1/ on weeds and yield of barley wad studied under field conditions hb/sup -1/. All the herbicides significantly reduce the dry weight of weed Maximum reduction (70%) was observed in terbutryn a 1.0 Kg a.i. ha/sup -1/ Growth and yield parameters like number of spike lets per spike. Number of grams per spike. 1000-grain weight. Biological yield. Grain yield straw yield and harvest index showed significant response to various herbicides doses under study. Application of Flurochloridone (Racer-25 (CS) a 0.44 kg a.i. ha/sup -1/ and Terbutryn (lgran-500 FW) a 1.0 kg a.i). The data further revealed that in general all herbicide application treatments exhibited superior performance in respect of growth and yield over control. (author)

  12. The effect of soil tillage system and weeding time on the growth of weed and yield of soybean (Glycine max (L. Merril

    Directory of Open Access Journals (Sweden)

    Husni Thamrin Sebayang

    2018-04-01

    Full Text Available The growth and yield of soybeans can decrease due to competition from weeds. Various efforts have been made to control the growth of weeds such as land preparation and weeding periods. An experiment to study the effect of soil tillage systems and weeding time on the growth of weeds and soybean crop yield (Glycine max (L. Merril has been done in Wringinsongo Village, Tumpang Sub-District, Malang Regency from February to May 2017. The split-plot design with three replicates was used with the soil tillage system as the main plot consisting of three levels, T0: no tillage, T1: minimum tillage, and T2: conventional tillage, and weeding time as the sub plot consisting of 4 levels, P0: no weeding, P1: weeding 1 time, P2: weeding two times and P3: weeding three times. The results showed that the dominant weed species before treatment were Amaranthus spinosus (Spiny amaranth, Cynodon dactylon (Bermuda grass, Cyperus rotundus (Purple nutsedge, Ageratum conyzoides (Billygoat weed, and Portulaca oleracea (Common purslane. After treatment, the dominant weed species were Cyperus rotundus (Purple nutsedge, Amaranthus spinosus (Spiny amaranth, Ageratum conyzoides (Billygoat weed, Physalis peruviana (Cape gooseberry, and Eclipta alba (False daisy. There was no significant difference of the dry weight of weeds in conventional tillage followed by weeding 3 times at 15, 30 and 45 days after planting, and minimum tillage and no tillage. For the yield of soybeans, conventional tillage followed by weeding 3 times at 15, 30 and 45 days after planting were not significant with that of minimum tillage. The yield of soybeans was lower than that of with no tillage and no weeding.

  13. Épocas de manejo químico de Brachiaria decumbens antecedendo o plantio direto de soja Brachiaria decumbens management times in soybean under no tillage system

    Directory of Open Access Journals (Sweden)

    A.S. Nunes

    2009-06-01

    Full Text Available O manejo químico da cobertura vegetal e a manutenção da palhada sobre o solo são preocupações comuns para os produtores que adotam o sistema plantio direto na região dos cerrados. Com o objetivo de estudar a influência da época de manejo químico de B. decumbens sobre o desenvolvimento e a produtividade da cultura da soja em sistema plantio direto, foram realizados dois ensaios a campo, respectivamente, com os cultivares BRS 154 e MG/BR 46-Conquista, no ano de 2003. Em cada ensaio, testaram-se quatro épocas de manejo de B. decumbens antecedendo a semeadura da soja (28, 14, 7 e 0 dias, utilizando-se o herbicida glifosato. Os ensaios foram conduzidos em delineamento inteiramente casualizado, utilizando-se três repetições no primeiro e quatro no segundo. Determinou-se a matéria seca da cobertura vegetal e avaliou-se a reinfestação de B. decumbens. Na cultura da soja, foram determinados: altura de inserção da primeira vagem, número de vagens por planta, umidade dos grãos, massa de 100 grãos e produtividade. Com base nos resultados obtidos, conclui-se que a época mais adequada para o manejo químico de B. decumbens com glifosato situa-se entre 7 e 14 dias antes da semeadura da cultura da soja e que a escolha da época de manejo químico da cobertura vegetal afeta de forma decisiva o desenvolvimento e a produtividade da cultura.Cover crop management and straw maintenance over the soil are common concerns for producers adopting the no tillage system in the cerrado region in Brazil. In order to study the influence of B. decumbens time management on soybean development and productivity under no tillage system, two assays were carried out using the cultivars BRS 154 and MG/BR 46-Conquista. For each cultivar, four B. decumbens management times prior to sowing of soybean (28, 14, 7 and 0 days were tested using glyphosate for weed control, in three replicates for cultivar BRS 154 and four replications for MG/BR 46-Conquista, in a

  14. Distribution of parthenium weed in peshawar valley, khyber pakhtunkhwa- pakistan

    Energy Technology Data Exchange (ETDEWEB)

    Khan, H.; Marwat, K. B.; Hassan, M. G.; Khan, M. A.; Hashim, S. [The University of Agriculture, Peshawar (Pakistan). Dept. of Weed Sciences

    2014-01-15

    Parthenium hysterophorus L. is a weed of national significance in Pakistan. Although infesting many districts of Khyber Pakhtunkhwa province, but more affected districts are Swabi, Mardan, Charsadda and Peshawar where it is highly invasive and invaded most of the open spaces roadsides, etc and threatening the local biodiversity. Field survey of four districts of the Peshawar valley, Khyber Pakhtunkhwa viz. Swabi, Mardan, Charsadda and Peshawar were carried out during May-June, 2009-2010 to study the distribution and invasion of parthenium weed. Twenty five locations were sampled from each district. Data regarding absolute and relative density, frequency, relative frequency, importance valve %, average importance value, constancy classes and importance value constancy index of parthenium weed and other weeds of the area were recorded by using (1x1 m2) quadrate. The mean data across the surveyed districts reveals that the flora is predominated by parthenium weed with the highest relative density of 42.68% among all species. It was followed by Cannabis sativa, Cynodon dactylon and Cyperus rotundus, with relative densities of 15.17, 13.49 and 5.96, respectively. At different locations, it was observed that parthenium weed is competing with Cannabis sativa which is not so aggressive and problematic weed. While in some areas parthenium weed has already replaced Cannabis sativa. Mean distribution data showed that parthenium weed infestation was abundant and almost not uniform in all districts, however highest relative frequency of 26.14% was recorded for parthenium weed followed by Cannabis sativa, Cynodon dactylon and Cyperus rotundus having relative frequency of 15.17, 13.49 and 9.14, respectively. Rumex crispus and Xanthium strumarium infatuated the smallest relative frequency at most of the locations studied thereby indicating them as insignificant among the weed flora of the study area. Importance value data revealed that P. hysterophorus, Cannabis sativa, Cynodon

  15. Distribution of parthenium weed in peshawar valley, khyber pakhtunkhwa- pakistan

    International Nuclear Information System (INIS)

    Khan, H.; Marwat, K.B.; Hassan, M.G.; Khan, M.A.; Hashim, S.

    2014-01-01

    Parthenium hysterophorus L. is a weed of national significance in Pakistan. Although infesting many districts of Khyber Pakhtunkhwa province, but more affected districts are Swabi, Mardan, Charsadda and Peshawar where it is highly invasive and invaded most of the open spaces roadsides, etc and threatening the local biodiversity. Field survey of four districts of the Peshawar valley, Khyber Pakhtunkhwa viz. Swabi, Mardan, Charsadda and Peshawar were carried out during May-June, 2009-2010 to study the distribution and invasion of parthenium weed. Twenty five locations were sampled from each district. Data regarding absolute and relative density, frequency, relative frequency, importance valve %, average importance value, constancy classes and importance value constancy index of parthenium weed and other weeds of the area were recorded by using (1x1 m2) quadrate. The mean data across the surveyed districts reveals that the flora is predominated by parthenium weed with the highest relative density of 42.68% among all species. It was followed by Cannabis sativa, Cynodon dactylon and Cyperus rotundus, with relative densities of 15.17, 13.49 and 5.96, respectively. At different locations, it was observed that parthenium weed is competing with Cannabis sativa which is not so aggressive and problematic weed. While in some areas parthenium weed has already replaced Cannabis sativa. Mean distribution data showed that parthenium weed infestation was abundant and almost not uniform in all districts, however highest relative frequency of 26.14% was recorded for parthenium weed followed by Cannabis sativa, Cynodon dactylon and Cyperus rotundus having relative frequency of 15.17, 13.49 and 9.14, respectively. Rumex crispus and Xanthium strumarium infatuated the smallest relative frequency at most of the locations studied thereby indicating them as insignificant among the weed flora of the study area. Importance value data revealed that P. hysterophorus, Cannabis sativa, Cynodon

  16. Dynamics of weed populations : spatial pattern formation and implications for control

    NARCIS (Netherlands)

    Wallinga, J.

    1998-01-01

    Modelling studies were carried out to analyse spatio-temporal dynamics of annual weed populations and to identify the key factors that determine the long-term herbicide use of weed control programmes. Three different weed control programmes were studied.

    In the first weed

  17. Weed Interference Effects on Leaves, Internode and Harvest Index of Dry Bean (Phaseolus vulgaris L.

    Directory of Open Access Journals (Sweden)

    Hossein GHAMARI

    2015-03-01

    Full Text Available The development of appropriate weed management strategies and efficient use of herbicides relies upon understanding weed-crop interactions. A field study was carried out to assess the effect of weed interference on leaves, internode and harvest index of dry bean (Phaseolus vulgaris L.. The experiment was established under a randomized complete block design with two types of weed interference treatments: plots with weeds and plots without weeds at different time intervals (0, 10, 20, 30, 40 and 50 days after crop emergence. The sigmoid Boltzmann model was used to quantify the crop traits as influenced by weed interference. Prolonged delays in weed removal reduced gradually the number of leaves of the crop. Weed interference decreased dry weight of leaves as well, so that the lowest value of it (33.49 g plant-1 was observed in full season during weed-infested treatment. Infestation of weeds affected the length of the crop internodes. While the weed interference duration increased, the length of the internodes decreased. Harvest index was also sensitive to weed competition. As the crop was kept weed-infested from the emergence for increasing periods of time, harvest index decreased to a value of 28.01%. A significant negative correlation between total biomass of weeds and dry bean traits (number of leaves, leaves dry weight, internode length and harvest index was observed. Therefore, weeds are able to adversely affect dry bean growth through constraining environmental resources and impairing leaves as the photosynthetic areas.

  18. Effect of tillage on the efficacy of CGA362622 on weed control in maize

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-03

    Dec 3, 2008 ... time and resources managing weeds. Tillage alone or in combination with good cropping methods is ... help in managing herbicide resistance weeds and may also increase weed density as well as reduce crop yield .... This change in weed compo- sition agrees with Richley et al. (1977) indicating shift.

  19. Integrating management techniques to restore sites invaded by mile-a-minute weed, Persicaria perfoliata

    Science.gov (United States)

    Ellen C. Lake; Judith Hough-Goldstein; Vincent. D' Amico

    2014-01-01

    Efforts to suppress an invasive weed are often undertaken with the goal of facilitating the recovery of a diverse native plant community. In some cases, however, reduction in the abundance of the target weed results in an increase in other exotic weeds. Mile-a-minute weed (Persicaria perfoliata (L.) H. Gross (Polygonaceae)) is an annual vine from...

  20. Histogram score contributes for reliability of DNA content estimatives in Brachiaria spp Notas do histograma contribuem para a confiabilidade das estimativas do conteúdo de DNA de Brachiaria spp

    Directory of Open Access Journals (Sweden)

    Ana Luiza de Oliveira Timbó

    2012-12-01

    Full Text Available Flow cytometry allows to estimate the DNA content of a large number of plants quickly. However, inadequate protocols can compromise the reliability of these estimates leading to variations in the values of DNA content the same species. The objective of this study was to propose an efficient protocol to estimate the DNA content of Brachiaria spp. genotypes with different ploidy levels using flow cytometry. We evaluated four genotypes (B. ruziziensis diploid and artificially tetraploidized; a tetraploid B. brizantha and a natural triploid hybrid, three buffer solutions (MgSO4, Galbraith and Tris-HCl and three species as internal reference standards (Raphanus sativus, Solanum lycopersicum e Pisum sativum. The variables measured were: histogram score (1-5, coefficient of variation and estimation of DNA content. The best combination for the analysis of Brachiaria spp. DNA content was the use of MgSO4 buffer with R. sativus as a internal reference standard. Genome sizes expressed in picograms of DNA are presented for all genotypes and the importance of the histogram score on the results reliability of DNA content analyses were discussed.A citometria de fluxo permite estimar o conteúdo de DNA de um grande número de plantas rapidamente. No entanto, protocolos inadequados podem comprometer a confiabilidade dessas estimativas, levando a variações nos valores de conteúdo de DNA para uma mesma espécie. Neste trabalho, objetivou-se propor um protocolo eficiente para a estimativa do conteúdo de DNA de genótipos de Brachiaria spp. com diferentes níveis de ploidia, utilizando a citometria de fluxo. Foram avaliados quatro genótipos (B. ruziziensis, diploide e tetraploidizada artificialmente; B. brizantha tetraploide e um híbrido natural triploide, 3 soluções tampões (MgSO4, Galbraith e Tris-HCl e três espécies como padrões de referência interno (Raphanus sativus, Solanum lycopersicum e Pisum sativum. As variáveis mensuradas foram: nota do

  1. Composição química e digestibilidade in vitro do feno de Brachiaria decumbens Stapf. tratado com uréia Chemical composition and in vitro digestibility of Brachiaria decumbens Stapf. hay treated with urea

    Directory of Open Access Journals (Sweden)

    Kátia Fernanda Gobbi

    2005-06-01

    Full Text Available Avaliaram-se os efeitos da adição de uréia em níveis crescentes sobre a composição química e digestibilidade in vitro da matéria seca (DIVMS do feno de Brachiaria decumbens colhida no estádio de pós-florescimento. O feno foi tratado com seis níveis de uréia (0, 2, 4, 6, 8 e 10%, com base na matéria seca (MS. A uréia foi dissolvida em quantidade de água suficiente para elevar o teor de umidade do feno para 30%. O delineamento experimental adotado foi o inteiramente casualizado, com três repetições. O feno tratado foi armazenado em sacos plásticos (2 kg/saco vedados, por 35 dias, e, após abertura, foram coletadas amostras para as análises químicas. Verificou-se que o teor de nitrogênio total (NT aumentou linearmente em função dos níveis crescentes de uréia. Os teores de NIDN e NIDA, em relação ao nitrogênio total (NIDN/NT e NIDA/NT, tiveram redução linear em função dos níveis crescentes de uréia, demonstrando aumento nos teores de nitrogênio disponível no material amonizado. A adição de uréia promoveu redução no teor de fibra em detergente neutro (FDN, fibra em detergente ácido (FDA e celulose. Os teores de hemicelulose e lignina não foram alterados pelo tratamento com uréia. A digestibilidade in vitro da matéria seca (DIVMS foi influenciada de forma quadrática pelos níveis de uréia, estimando-se valor máximo de 68, 9% para o nível de 7, 15% de uréia. A amonização com uréia alterou a composição química e a digestibilidade do feno de Brachiaria decumbens, melhorando o valor nutritivo do material tratado.An experiment was conducted to evaluate the effects of urea treatment on the chemical-bromatologic compounds and in vitro dry matter digestibility (IVDMD of Brachiaria decumbens hay. The hay were reconstituted with water to get final forage moisture concentration of 30%, and treated with urea at 0, 2, 4, 6, 8, and 10% of the forage dry matter. A completely randomized design with three

  2. Possíveis efeitos alelopaticos de Brachiaria decumbens sobre o crescimento inicial de limão cravo (Citrus limonia The possible allelopathic effects of Brachiaria decumbens on initial development of root stock of Citrus limonia

    Directory of Open Access Journals (Sweden)

    L. S. Souza

    1997-01-01

    Full Text Available Foram estudados os possíveis efeitos alelopáticos da incorporação da matéria seca da parte aérea de Brachiaria decumbens, ao substrato, nas concentrações de 0, 1,5 e 3,0% (p/p sobre o crescimento inicial de limão cravo (Citrus limonia Osbeck, em casa-de-vegetação. Foram determinados os parâmetros biométrico s e algumas propriedades físico-químicas da solução do solo. A maior quantidade de matéria seca incorporada causou redução de 44, 42, 57 e 55% das médias da altura, teor de clorofila, área foliar e acúmulo de matéria seca total, respectivamente. O potencial osmótico, pH, condutividade elétrica e os teores de nutrientes da solução do solo foram alterados. Provavelmente, a redução do crescimento observada seja devida a deficiência de N causada por alterações na dinâmica do N-solo em função da incorporação de B. decumbens.It was studied the possible allelopathic effect of Brachiaria decumbens on initial development of Citrus limonia in greenhouse. The dry matter was incorporated into the soil in 0, 1,5, 3,0% (w/w-proportion. Biometric parameters and physic propert ies of soil were determined by soil solutio n. Greatest propotion reduced all the biometric parameters analyse d. Physical properties of nutrient levels (except N of soil did not observed significantly alterations. Greatest proportion reduced the average stem diameter of Citrus limonia at 57%. Probably, these results were due to lack in nitrogen level observed in soil solution.

  3. Wallowa Canyonlands Weed Partnership : Completion Report November 19, 2009

    Energy Technology Data Exchange (ETDEWEB)

    Porter, Mark C.; Ketchum, Sarah

    2008-12-30

    Noxious weeds threaten fish and wildlife habitat by contributing to increased sedimentation rates, diminishing riparian structure and function, and reducing forage quality and quantity. Wallowa Resources Wallowa Canyonlands Partnership (WCP) protects the unique ecological and economic values of the Hells Canyon grasslands along lower Joseph Creek, the lower Grande Ronde and Imnaha Rivers from invasion and degradation by noxious weeds using Integrated Weed Management techniques. Objectives of this grant were to inventory and map high priority weeds, coordinate treatment of those weeds, release and monitor bio-control agents, educate the public as to the dangers of noxious weeds and how to deal with them, and restore lands to productive plant communities after treatment. With collaborative help from partners, WCP inventoried {approx} 215,000 upland acres and 52.2 miles of riparian habitat, released bio-controls at 23 sites, and educated the public through posters, weed profiles, newspaper articles, and radio advertisements. Additionally, WCP used other sources of funding to finance the treatment of 1,802 acres during the course of this grant.

  4. Weed flora in organically grown spring cereals in Finland

    Directory of Open Access Journals (Sweden)

    J. SALONEN

    2008-12-01

    Full Text Available The weed flora in organically grown spring cereals was investigated in southern and central Finland in 1997-1999 with the primary purpose of determining the species composition and the level of weed infestation. Altogether 165 fields were surveyed in the middle of the growing season. A total of 126 weed species were found, of which 42 exceeded the frequency level of 10%. The most frequent weed species were Chenopodium album, Stellaria media, Galeopsis spp. and Viola arvensis. Elymus repens was the most frequent grass species. The average density of weeds was 469 plants m-2 (median 395, and the air-dry biomass was 678 kg ha-1 (median 567 which accounted for 17% of the total biomass of the crop stand. Infestation by Chenopodium album and the perennial species Elymus repens, Cirsium arvense and Sonchus arvensis is of major concern. Weed control strategies should include direct control measures to overcome weed problems related to the conversion period from conventional to organic growing.

  5. Interactions between pre- and post-emergence weed harrowing in spring cereals

    DEFF Research Database (Denmark)

    Brandsæter, L.O.; Mangerud, K.; Rasmussen, Jesper

    2012-01-01

    that pre- and post-emergence harrowing interact positively, that a combination gives more stable weed control effects than pre- and post-emergence weed harrowing used alone, and that a harrow type with bent tines is more aggressive and suitable on hard-packed soils than a harrow with strait tines...... the average effect of post-emergence harrowing was 47% on weed density and 41% on weed biomass. The combined effect of pre- and post-emergence weed harrowing was 61% on weed density and 54% on weed biomass. The combination did not give more stable weed control effects than pre- and post-emergence weed...... harrowing used alone. Pre-emergence harrowing increased the average crop yield by 6.2%, post-emergence harrowing by 4.0% and the combined effect was 10%. Crop yield was mainly increased on hard-packed soils. Weed and crop responses varied strongly among experiments, but the efficacy of pre- and post...

  6. Fontes, doses e modos de aplicação de fósforo na recuperação de pastagem com brachiaria Sources, doses, and application method of phosphorus in the recovery of brachiaria pasture

    Directory of Open Access Journals (Sweden)

    Alfredo Yuji Ieiri

    2010-10-01

    Full Text Available Objetivando-se avaliar diferentes fontes, doses e métodos de aplicação de fósforo na recuperação da Brachiaria decumbens, um experimento foi conduzido na Fazenda Caminho das Pedras, município de Uberlândia-MG, em Latossolo Vermelho distrófico, textura média, entre novembro de 2003 e abril de 2004. Os tratamentos constaram de três fontes de fósforo (Superfosfato Triplo, Termofosfato magnesiano e hiperfosfato de Gafsa nas dosagens de 0; 50; 100 e 150 kg ha-1 de P2O5, com manejo incorporado e não incorporado, em três repetições, no delineamento de blocos casualizados. Foram utilizadas parcelas de 2,0 x 5,0 m, as quais foram adubadas uniformemente com 330 kg ha-1 de N e 220 kg ha-1 K2O, na forma de uréia + sulfato de amônio e cloreto de potássio, respectivamente. Foi avaliada a produtividade da Brachiaria em três cortes da parte aérea, em um intervalo de 30 dias entre os cortes. A aplicação de fósforo com diferentes fontes e doses promoveu incremento na produtividade da Brachiaria, porém não houve diferença comparando-se os métodos de aplicação. A maior resposta foi obtida com 150 kg ha-1 de P2O5, na forma de superfosfato triplo com produtividade média de 2997 kg ha-1 de MS por corte, e a menor produtividade ocorreu no tratamento com 50 kg ha-1 de P2O5 na forma de hiperfosfato de Gafsa. Houve aumento na porcentagem do fósforo foliar e do fósforo no solo, com aumento da dose em todas as fontes, em ambos extratores. Na avaliação dos extratores, o Mehlich-1 apresentou maior extração na fonte hiperfosfato de Gafsa, contrariando os resultados de produção.The objective of this work was to evaluate different sources, doses and methods of phosphorus application in the recovery of Brachiaria decumbens. An experiment was installed on the "Caminho das Pedras" Farm, in Uberlândia-MG, in Acroustox soil, medium texture, between November 2003 and April 2004. The treatments were three phosphorus sources (Triple Superphosphate

  7. Capabilities of unmanned aircraft vehicles for low altitude weed detection

    Science.gov (United States)

    Pflanz, Michael; Nordmeyer, Henning

    2014-05-01

    Sustainable crop production and food security require a consumer and environmental safe plant protection. It is recently known, that precise weed monitoring approaches could help apply pesticides corresponding to field variability. In this regard the site-specific weed management may contribute to an application of herbicides with higher ecologically aware and economical savings. First attempts of precision agriculture date back to the 1980's. Since that time, remote sensing from satellites or manned aircrafts have been investigated and used in agricultural practice, but are currently inadequate for the separation of weeds in an early growth stage from cultivated plants. In contrast, low-cost image capturing at low altitude from unmanned aircraft vehicles (UAV) provides higher spatial resolution and almost real-time processing. Particularly, rotary-wing aircrafts are suitable for precise path or stationary flight. This minimises motion blur and provides better image overlapping for stitching and mapping procedures. Through improved image analyses and the recent increase in the availability of microcontrollers and powerful batteries for UAVs, it can be expected that the spatial mapping of weeds will be enhanced in the future. A six rotors microcopter was equipped with a modified RGB camera taking images from agricultural fields. The hexacopter operates within predefined pathways at adjusted altitudes (from 5 to 10 m) by using GPS navigation. Different scenarios of optical weed detection have been carried out regarding to variable altitude, image resolution, weed and crop growth stages. Our experiences showed high capabilities for site-specific weed control. Image analyses with regard to recognition of weed patches can be used to adapt herbicide application to varying weed occurrence across a field.

  8. Weed infestation of spring common wheat (Triticum aestivum L. grown in monoculture depending on the cover crop and weed control method

    Directory of Open Access Journals (Sweden)

    Dorota Gawęda

    2012-10-01

    Full Text Available The aim of this 3-year field study was to evaluate the effect of some stubble crops and in-crop weed control methods on the species composition, number and air-dry weight of weeds in a wheat crop grown in short-term monoculture. The study was conducted in the period 2009-2011 in the Uhrusk Experimental Farm on mixed rendzina soil classified as very good rye soil complex. It included various types of stubble crops ploughed in each year (control treatment without cover crop, white mustard, lacy phacelia, a mixture of legumes – narrow-leaf lupin + field pea and methods of weed control in spring wheat (mechanical, mechanical and chemical, chemical weed control. On average during the study period, all stubble crops used reduced the air-dry weight of weds in the treatments with mechanical weed management relative to the control treatment. Irrespective of the weed control method, the number of weeds in the wheat crop was significantly lower only after the ploughing in of white mustard. Mechanical weed management proved to be less effective in reducing the number and dry weight of weeds compared to other weed control methods. The white mustard and legume mixture cover crops had a reducing effect on the number of weed species in relation to the treatment without cover crops. The highest floristic diversity of weed communities was found in the spring wheat crop in which only mechanical weeding alone was used.

  9. Cytogenetic evidence for genome elimination during microsporogenesis in interspecific hybrid between Brachiaria ruziziensis and B. brizantha (Poaceae

    Directory of Open Access Journals (Sweden)

    Andréa Beatriz Mendes-Bonato

    2006-01-01

    Full Text Available Microsporogenesis was analyzed in an interspecific hybrid between an artificially tetraploidized sexual accession of Brachiaria ruziziensis (R genome and a natural apomictic tetraploid accession of B. brizantha (B genome. Chromosomes associated predominantly as bivalents. From this phase to the end of meiosis, chromosomes presented irregular segregation and abnormal arrangement in the metaphase plate. During metaphase I, in 27.8% of meiocytes, bivalents were distributed in two metaphase plates. In anaphase I, two distinct and typical bipolar spindles were formed. In 29.7% of pollen mother cells, one genome did not divide synchronically, with chromosomes lagging behind or not segregating at all. The second division was very irregular, resulting in polyads. Based on previous results from analysis of a triploid hybrid between these species, where the R genome was eliminated by asynchrony during meiosis, it is suggested that the laggard genome in this hybrid also belongs to B. ruziziensis.

  10. A New Hoe Blade for Inter-Row Weeding

    DEFF Research Database (Denmark)

    Green, O.; Znova, L.; Melander, Bo

    2016-01-01

    and weeds are relatively small. The term ‘Ducksfoot’ covers a range of hoe blade configurations where all have some resemblance with the shape of a ducks foot. However, the ‘Ducksfoot’ blade is not an optimal solution for weed control in narrow inter-row spaces. Several disadvantages have been encountered...... and the draft forces needed to pull it were approx. half those measured for a ‘Ducksfoot’ blade. The weeding features of the new L-blade will be further studied under field conditions....

  11. Enzimas fibrolíticas exógenas en la digestibilidad in vitro de cinco ecotipos de Brachiaria

    Directory of Open Access Journals (Sweden)

    Juan H. Avellaneda-Cevallos

    2007-01-01

    Full Text Available En zi mas fi bro lí ti cas exó ge nas en la di ges ti bi li dad in vi tro de cin co eco ti pos de Bra chia ria. Este experimento se llevó a cabo en la Estación Experimental del Colegio de Postgraduados, en Montecillo, Estado de México, México, durante el 25 abril y el 27 noviembre de 2002. Se usó la primera fase de la técnica de Tilley y Terry (3, 6, 12, 24, 48, 72 h incubación con el objetivo de medir el efecto de un compuesto enzimático fibrolítico exógeno (enzima; Fibrozyme®; 0 y 1,5 g enzima/kg MS en la digestibilidad in vitro (DIV de MS, FDN y FDA de henos de cinco ecotipos de Brachiaria [brizantha var. Toledo (BT; ruziziensis x decumbens CIAT 46024 (RD; decumbens var. Señal (DS; ruziziensis x brizantha CIAT 36061 cv. Mulato (RBM; brizantha var. Insurgente (BI]. La DIVMS a las 48 y 72 h, para 0 y 1,5 g enzima, fue mayor (p<0,05 para los ecotipos BT y BI, respecto a RD, DS y RBM. La DIVFDN a las 48 y 72 h, para 0 y 1,5 g enzima, fue mayor (p<0,05 para BT y BI, respecto a RD, DS y RBM. La enzima aumentó (p<0,05 la DIVFDN sólo para el ecotipo RD a las 72 h; además, incrementó la DIVFDA para BT a 12 h; BT y DS a 24 h; BT, RD y BI a 48 h. Por tanto, las enzimas fibrolíticas aumentaron la digestibilidad in vitro de la pared celular de cinco ecotipos de Brachiaria.

  12. Cutting weeds with a CO2 laser

    DEFF Research Database (Denmark)

    Heisel, T.; Schou, Jørgen; Christensen, S.

    2001-01-01

    Stems of Chenopodium album. and Sinapis arvensis. and leaves of Lolium perenne. were cut with a CO2 laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after...... treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose-response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO2 laser than C. album....... When stems were cut below the meristems, 0.9 and 2.3 J mm(-1) of CO2 laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close...

  13. Fungal Phytotoxins in Sustainable Weed Management.

    Science.gov (United States)

    Vurro, Maurizio; Boari, Angela; Casella, Francesca; Zonno, Maria Chiara

    2018-01-01

    Fungal phytotoxins are natural secondary metabolites produced by plant pathogenic fungi during host-pathogen interactions. They have received considerable particular attention for elucidating disease etiology, and consequently to design strategies for disease control. Due to wide differences in their chemical structures, these toxic metabolites have different ecological and environmental roles and mechanisms of action. This review aims at summarizing the studies on the possible use of these metabolites as tools in biological and integrated weed management, e.g. as: novel and environmentally friendly herbicides; lead for novel compounds; sources of novel mechanisms of action. Moreover, the limiting factors for utilizing those metabolites in practice will also be briefly discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  14. The Effect of Laser Treatment as a Weed Control Method

    DEFF Research Database (Denmark)

    Mathiassen, Solvejg K; Bak, Thomas; Christensen, Svend

    2006-01-01

    at the cotyledon stage. Experiments were carried out under controlled conditions, using pot-grown weeds. Two lasers and two spot sizes were tested and different energy doses were applied by varying the exposure time. The biological efficacy was examined on three different weed species: Stellaria media (common...... was related to wavelength, exposure time, spot size and laser power. The efficacy also varied between the weed species. The results indicate that the efficacy of laser treatments can be improved by a more precise pointing of the laser beam towards the apical meristems and optimisation of the energy density...... (exposure time and spot size of the laser beam). The experiment also showed a significant difference between two wavelengths. In order to improve the performance and to validate the efficacy on a broader spectrum of weed species, further research and development is needed....

  15. Effects of Weed Control and Cow Dung Manure on Growth ...

    African Journals Online (AJOL)

    ISSN 0794-5698. Effects of Weed Control and Cow Dung Manure on Growth Performance of Quality Protein Maize in ... worldwide on over 159.5 million hectares in the year. 2010. ...... Fertilizer company of Nigeria, NAFCON, Port. Harcourt.

  16. Aquatic weeds: their implications in Indian nuclear industry

    International Nuclear Information System (INIS)

    Rao, T.S.; Anup Kumar, B.; Aruna Jyothi, K.; Satpathy, K.K.

    2000-01-01

    The aquatic weed infestation of KAPS cooling water system, MAPS open reservoir, and the growth of filamentous algae and bacteria in the feed water unit of HWP (Kota), was investigated. The aquatic weeds identified were: Ceratophyllum, Elodea, Hydrilla verticillata, Najas and Vallisneria species. However, at HWP (Kota) filamentous alga (Nostoc punchiformis) and bacteria (Sphaerotilus natans) were found in plenty. The metabolic products when assayed in the form of total carbohydrate content released by weeds was 3.7 mg gm -1 biomass. The metabolic products adsorb on to the resin matrix and impaired its performance at HWP (K), enhanced bacterial growth on the resin beads and furthered resin deterioration. Besides, the growth of aquatic weeds also influenced the pH of the cooling water, thereby vitiating the water treatment programme. (author)

  17. Weed biomass and economic yield of wheat (Triticum aestivum) as ...

    African Journals Online (AJOL)

    Yomi

    2012-01-24

    154 ... to realize the maximum yield potential of the crop at lower input costs ... only acceptable way for effective weed management in future (Marwat et al., ..... Jarwar AD, Tunio SD, Majeedano HI, Kaisrani MA. (1999). Efficacy.

  18. Weed biomass and economic yield of wheat (Triticum aestivum) as ...

    African Journals Online (AJOL)

    Yomi

    2012-01-24

    Jan 24, 2012 ... INTRODUCTION ... to control weeds in conjunction with cultural practices. Jarwar et al. (1999) .... Wheat grain yield is an interplay of yield components especially ... The biological yield expresses the overall growth of crop.

  19. Evaluation of Botanical Herbicides against Common Weed Species ...

    African Journals Online (AJOL)

    test the inhibitory potential of essential oils extracted from eight locally available plants and .... from C. citratus was in different as weed growth observed with standard ..... NB:-Con = Control, EC = Eucalyptus citrodora, CW = Cymbopogon ...

  20. Weed management in banana production: The use of Nelsonia ...

    African Journals Online (AJOL)

    EJIRO

    reduction in abundance was more pronounced during the dry season when cover crop growth was dense, than in ... The main method of weed control is by use of herbicides ..... with organic plastic and paper mulches in small-scale vegetable.

  1. EFEITO DE CYNAZINE E LINURON NO CONTROLE DE PLANTAS DANINHAS E NA PRODUTIVIDADE DA CEBOLA (Allium cepa L.d EFFECT OF CYANAZINE AND LINURON ON WEEDS AND PRODUCTIVITY IN ONION CROP (Allium cepa L.

    Directory of Open Access Journals (Sweden)

    Natan Fontoura da Silva

    2007-09-01

    Full Text Available

    Foi realizado um experimento com cebola (Allium cepa L. cv . Texas Early Grano - 502, transplantada em Goiânia, Goiás, no período de junho a novembro de 1988, visando ao controle de plantas daninhas com cyanazine e linuron aplicados após o transplante da cultura. Nas condições em que o ensaio foi realizado, concluiu-se que cyanazine e linuron provocaram fitotoxicidade na cultura da cebola, causando redução na produção em relação à testemunha. Cyanazine controlou Portulaca oleracea e Amaranthus spp. até 45 dias e Commelina virginica, Eleusine indica e Brachiaria plantaginea até 30 dias após a aplicação. Linuron controlou P. oleracea, Amaranthus spp. e B. plantaginea até 45 dias após a aplicação, mas não controlou eficientemente C. virginica, E. indica e Digitaria horizontalis.

    This work presents the results of a field experiment carried out in Goiânia, State of Goiás, Brazil, to estimate the efficiency of herbicides in controlling weeds in onion crop of Texas Early Grano 502. Cyanazine controlled Portulaca oleracea, Amaranthus spp. till 45 days, and Commelina virginica. Eleusine indica and Brachiaria plantaginea till 30 days after application. Linuron controlled P. oleracea, Amaranthus spp. and B. plantaginea during 45 days. Both herbicides showed phytotoxicity decreasing the onion productivity.

  2. Weed management practices in natural ecosystems: a critical overview

    Directory of Open Access Journals (Sweden)

    C.F. Reinhardt

    2000-07-01

    Full Text Available Increasing public pressure against the use of pesticides and other agricultural inputs has placed increased emphasis on the development of ecologically based pest management. One distinct reaction of the Weed Science discipline has been the swing away from herbicide research to increased research on the basic biology and ecology of weeds in hopes of reduced reliance on "technological crutches" such as herbicides and other practices that are potentially harmful to the environment. Biological control is the long-standing alternative to the use of herbicides and interest in the former practice has been boosted by the realization that the use of herbicides may lead to the development of herbicide resistance in weed populations, and that herbicide residues occur in surface and groundwater. Supporters of herbicide use would point out that biological control is generally not effective in crop production systems, and is basically slow-acting. Debates between protagonists for the exclusive use of one or the other weed management practice tend to obscure the benefits that integration of different techniques are likely to have. For natural ecosystems it is proposed that integration of the more subtle practice of biological control with the use of herbicides, which relatively quickly overwhelm a biological system with mortality, is likely to be the most effective weed management tool. Different weed management practices that could be considered in natural ecosystems are discussed in terms of three key performance rating criteria, viz. activity, selec- tivity and persistence In this concise review, general discussion is focussed on the fundamentals of weed management practices, with the view to promote concept-based approaches that are critical for the development of effective weed management strate- gies.

  3. Chemical Weed Control Increases Survival and Growth in Hardwood Plantings

    Science.gov (United States)

    Gayne G. Erdmann

    1967-01-01

    In a plantation of four hardwood species on a silt loam soil planted to 1-0 stock, 4 pounds of active atrazine or simazine controlled weeds effectively without injuring the trees. Chemical weed control was better on plowed and disked ground than on unprepared ground. Yellow-poplar and white ash grew faster on prepared ground. Black walnut and red oak did not respond...

  4. Crop characteristics and weed Interactions of diverse Rrecurrent Inbred Lines (RILs) from a weed-suppressive x non-suppressive rice mapping population

    Science.gov (United States)

    ndica rice genotypes with enhanced weed suppression traits have been previously identified as potentially useful in supplementing weed control efforts in drill-seeded systems in the southern USA. A particularly weed-suppressive indica genotype (PI 312777) that was also high tillering and high yield...

  5. Weeding method and pre-sowing tillage effects on weed growth and pearl millet yield in a sandy soil of the West African Sahelian zone.

    NARCIS (Netherlands)

    Klaij, M.C.; Hoogmoed, W.B.

    1996-01-01

    Weed control for the West African Sahel rainfed crops is done mainly manually, resulting in high labor requirements. Because of the seasonality of rainfed farming, weed control is often late and incomplete, resulting in considerable losses in crop yield. We examined the case of weed control in

  6. INFLUENCE OF CROPPING SYSTEM AND WEED MANAGEMENT PRACTICE ON EMERGENCE, GROWTH OF WEEDS, YIELD OF MAIZE (Zea mays L. AND COWPEA (Vigna unguiculata L.

    Directory of Open Access Journals (Sweden)

    Felix Ogar Takim

    2014-06-01

    Full Text Available The effects of cropping system and weed management practice on weed seedling emergence, weed biomass production and yield of maize and cowpea were examined at Ilorin, in the southern Guinea savanna (9°29' N, 4°35' E and 307 m ASL of Nigeria. Weed emergence occurred throughout the 3-15 weeks after planting (WAP. Forty-three weed species belonging to 38 genera within 20 families were encountered. Fimbristylis littoralis Gaudet, Tridax procumbens L and Eleusine indica Gaertn were the most prevalent weed species. Cropping system and weed management practice significantly affected weed emergence. Significantly (p≤0.05 lower number of weeds emerged in the intercropped and herbicide treated plots while higher weed densities and weed biomass were recorded in the uncropped and unweeded control plots than in the other plots. While aggregate crop yields were significantly higher in the intercropped than in the sole plots, component crop yields were higher under the sole cropping than in the intercrop. The implication of the results on weed management is discussed.

  7. Atividade alelopática de substâncias químicas isoladas do Capim-Marandu e suas variações em função do pH Allelopathic activity of chemical substances isolated from Brachiaria brizantha cv. Marandu and their variations in function of pH

    Directory of Open Access Journals (Sweden)

    L.S. Santos

    2008-01-01

    Full Text Available Este trabalho teve por objetivos isolar, identificar e caracterizar a atividade alelopática de substâncias químicas produzidas pela Brachiaria brizantha cv. Marandu e determinar as variações na atividade dessas substâncias em função da variação do pH da solução. A atividade alelopática foi realizada em bioensaios de germinação e desenvolvimento da radícula e do hipocótilo, utilizando as plantas daninhas malícia (Mimosa pudica e mata-pasto (Senna obtusifolia como receptoras. Os efeitos do pH foram analisados na faixa de 3,0 a 9,0. Os triterpenos pentacíclicos friedelina e epifriedelinol isolados da parte aérea de B. brizantha apresentaram baixa atividade inibitória na germinação de sementes e no desenvolvimento da radícula e do hipocótilo das duas plantas daninhas. As duas substâncias apresentaram comportamento diferenciado em relação à variação do pH da solução, com inibições mais marcantes em relação à planta daninha mata-pasto.This work aimed to isolate, identify and determine the allelopathic activity of the chemical substances produced by Brachiaria brizantha cv. Marandu and to verify the effects of the pH in the solution on the activity of these compounds. The allelopathic activity was evaluated based on germination bioassays and radicle and hypocotyl growth using the species 'malícia' (Mimosa pudica and 'mata-pasto' (Senna obtusifolia as receptors. The effect of pH was analyzed in a range from 3.0 to 9.0. The pentacyclic triterpenes friedelin and epifriefelinol isolated from the shoots of B. brizantha showed a low inhibitory activity against seed germination and radicle and hypocotyl growth of the two receptor plants evaluated. The pentacyclic triterpenes friedelin and epifrifelinol presented differentiated behaviors in relation to the pH variation in the solution, with stronger inhibition activity against the weed 'mata-pasto'.

  8. Restrição do 16S-23S DNAr intergênico para avaliação da diversidade de Azospirillum amazonense isolado de Brachiaria spp. Restriction of 16S-23S intergenic rDNA for diversity evaluation of Azospirillum amazonense isolated from different Brachiaria spp.

    Directory of Open Access Journals (Sweden)

    Fábio Bueno dos Reis Junior

    2006-03-01

    Full Text Available O objetivo deste trabalho foi avaliar a diversidade intra-específica de isolados de Azospirillum amazonense e estabelecer a possível influência de diferentes espécies de Brachiaria ssp. e diferentes condições edafoclimáticas. A caracterização da diversidade desses isolados foi conduzida, utilizando-se a análise de restrição da região intergênica 16S-23S DNAr. As estirpes estudadas separaram-se em dois grupos, definidos a 56% de similaridade. As espécies de Brachiaria ssp. influenciaram a diversidade de estirpes. A maioria dos isolados oriundos de B. decumbens e B. brizantha está inserida no primeiro grupo, enquanto os oriundos de B. humidicola concentram-se no segundo grupo.The aim of this work was to study the intra-specific diversity of Azospirillum amazonense isolates and to establish possible influences of different Brachiaria spp. and edaphoclimatic conditions. The characterization of the diversity among the isolates of A. amazonense studied was conducted using restriction analysis of the 16S-23S rDNA intergenic spacer region. The evaluated strains were separated in two groups, defined at 56% of similarity. Brachiaria spp. showed effects on strain diversity. Most part of the isolates from B. decumbens and B. brizantha are inserted in the first group, while B. humidicola isolates concentrate in the second group.

  9. Nitrogen availability in an apple orchard with weed management

    Directory of Open Access Journals (Sweden)

    Gustavo Brunetto

    2018-05-01

    Full Text Available ABSTRACT: Weed management in apple orchards (Malus domestica can affect the leaching of nitrogen (N in soil. The study aimed to evaluate the potential leaching of N forms in soil of an apple orchard with different weed management treatments. The experiment was conducted in an apple orchard implanted in 2008. In October 2011, 80 plants were selected and the following treatments were implemented: no weed management (NM, desiccation of weeds on the tree row with herbicide use (DR and mechanical mowing of weeds on the tree row (MR. Yield was evaluated in the 2011/2012, 2012/2013 and 2013/2014 crop seasons. In May 2012 porous cup lysimeters were installed in the NM, DR and MR treatments. In the solution collected at 0.20m, NH4 +-N and NO3 --N were analyzed sixteen times and mineral N concentration was calculated. The highest concentrations of NO3 --N and mineral N occurred in soil solution with DR, which increases availability of the nutrient to apple trees, but also enhances the potential losses. Weed management and N flow in the solution did not affect apple yield.

  10. Weeds Cause Losses in Field Crops through Allelopathy

    Directory of Open Access Journals (Sweden)

    Ali ZOHAIB

    2016-03-01

    Full Text Available A large number of weeds are known to be associated with crops and causing economic losses. Weeds interfere with crops through competition and allelopathy. They produce secondary metabolites known as allelochemicals, which belong to numerous chemical classes such as phenolics, alkaloids, fatty acids, indoles, terpens etc. However, phenolics are the predominant class of allelochemicals. The allelochemicals release from weed plants takes place through leaf leachates, decomposition of plant residues, volatilization and root exudates. Weeds leave huge quantities of their residues in field and affect the associated, as well as succeeding crops, in various cropping systems. Liberation of allelochemicals from weeds affects the germination, stand establishment, growth, yield and physiology of crop plants. They cause substantial reduction in germination and growth of the crop plants by altering various physiological processes such as enzyme activity, protein synthesis, photosynthesis, respiration, cell division and enlargement, which ultimately leads to a significant reduction in crop yield. In crux, allelopathic weeds represent a potential threat for crop plants and cause economic losses.

  11. The impact of stubble crop on spring barley weed infestation

    Directory of Open Access Journals (Sweden)

    Eleonora Wrzesińska

    2016-09-01

    Full Text Available The condition and degree of weed infestation were determined in a spring barely crop grown in a short-term monoculture after mulching the soil with plants grown as a stubble crop (the control treatment without cover crop – lacy phacelia, white mustard, sunflower. The field experiment was carried out in 2010–2013 on good rye soil complex using a split-block design in four replications. The obtained results (the mean from all years of the experiment showed that the stubble crop, especially sunflower, reduced the diversity of weed species without causing at the same time changes in weed species dominance. In all the control treatments of the experiment, Chenopodium album and Fallopia convolvulus were the dominant species. The degree of spring barley weed infestation depended on the species grown in the cover crop. White mustard and lacy phacelia slightly increased the number of weeds but their fresh matter significantly increased. However, the sunflower cover crop significantly increased the number of weeds without any substantial differentiation of their fresh mass.

  12. Robust Crop and Weed Segmentation under Uncontrolled Outdoor Illumination

    Directory of Open Access Journals (Sweden)

    Hong Y. Jeon

    2011-06-01

    Full Text Available An image processing algorithm for detecting individual weeds was developed and evaluated. Weed detection processes included were normalized excessive green conversion, statistical threshold value estimation, adaptive image segmentation, median filter, morphological feature calculation and Artificial Neural Network (ANN. The developed algorithm was validated for its ability to identify and detect weeds and crop plants under uncontrolled outdoor illuminations. A machine vision implementing field robot captured field images under outdoor illuminations and the image processing algorithm automatically processed them without manual adjustment. The errors of the algorithm, when processing 666 field images, ranged from 2.1 to 2.9%. The ANN correctly detected 72.6% of crop plants from the identified plants, and considered the rest as weeds. However, the ANN identification rates for crop plants were improved up to 95.1% by addressing the error sources in the algorithm. The developed weed detection and image processing algorithm provides a novel method to identify plants against soil background under the uncontrolled outdoor illuminations, and to differentiate weeds from crop plants. Thus, the proposed new machine vision and processing algorithm may be useful for outdoor applications including plant specific direct applications (PSDA.

  13. Analysis of weed flora in conventional and organic potato production

    Directory of Open Access Journals (Sweden)

    Nikolić, Lj.

    2013-12-01

    Full Text Available Composition of weed flora is highly dynamic and depends upon great number of factors, of which cultural practices that are applied by humans in certain crops are the most important. One of the most frequently grown plants in the world and in our country is potato (Solanum tuberosum L., Solanaceae, due to its high biological and nutritive value. Therefore, in the paper was presented taxonomic analysis of weed flora in potato grown conventionally and according to the principles of organic agricultural production, with the intention to point out to eventual differences between present weeds. Of the total number of identified species, from phylum Equisetophyta and class Equisetopsida, in organic potato crop, was determined only one, Equisetum arvense. Of remaining 38 weeds from phylum Magnoliophyta., classified into two classes, Magnoliopsida and Liliopsida. On both of potato growing systems, 39 weed species were found, classified into 16 families and 32 genus. Of the total number, 31 species was identified in conventional potato crop, and only 23 species in potato crop grown according to organic principles, which is for about quarter less. Biological spectrum of weed flora in both potato growing systems is pronouncedly of terrophytic – geophytic type. In the spectrum of area types were recorded differences, i.e. in the conventional potato crop represented are only widely distributed species, while in the organic crop, beside species of wide distribution are also present elements of Pontic group.

  14. Researches regarding glyphosate effectiveness on the degree of weed control in grape plantation

    Directory of Open Access Journals (Sweden)

    Monica NEGREA

    2010-11-01

    Full Text Available In this paper was determined the control degree of weeds in grape plantation, Burgund variety, when is using chemical treatments with herbicides and agro-technique measures. Herbicide used was Roundup 3 l/ha and 4l/ha (glyphosate isopropyl amine salt 360 g/l applied in 4 experimental variants. It was determined the weed presence degree, the type of weeds destroyed and the degree of their participation. Predominant weed species in studied grape plantation, were: Agropyron repens (20.15%, Geranium dissectum (17.91%, Capsella bursa pastoris (15.67% and Avena fatua (13.43%. Ephemeral weeds Veronica hederifolia and Stellaria media had a participation rate of 8.96%. Perennial weeds represented 40.30% while annual weeds are 59.70% . The herbicide Roundup provides most effective control in a dose of 3 or 4 l/ha, combined with mechanical weeding + 1 manual weeding, control rates being over 90%.

  15. Image analysis as a non-destructive method to assess regrowth of weeds after repeated flame weeding

    DEFF Research Database (Denmark)

    Rask, Anne Merete; Kristoffersen, Palle; Andreasen, Christian

    2013-01-01

    picture of the long-term effect of repeated treatments. Image analysis was most useful for assessing the effect of repeated treatments when weed cover was relatively low (below 40%) and when plots contained relatively much withered plant material. However, when weed cover is close to 100%, dry weight......, and therefore it may influence the long-term effect of repeated treatments. Visual assessment of weed cover or image analysis do not affect the remaining parts of the weed plants after treatment, but the methods may have other disadvantages. In order to evaluate and compare three methods we measured changes...... in vegetation cover of perennial ryegrass after flaming by (1) a simple image analysis programme counting green pixels, (2) visual assessment of images and (3) by taking biomass samples. Plants were flame treated with eight different dosages (0, 20, 30, 35, 45, 60, 90 and 180 kg propane ha-1) and with various...

  16. [Spatial and temporal dynamics of the weed community in the Zoysia matrella lawn].

    Science.gov (United States)

    Liu, Jia-Qi; Li, You-Han; Zeng, Ying; Xie, Xin-Ming

    2014-02-01

    The heterogeneity of species composition is one of the main attributes in weed community dynamics. Based on species frequency and power law, this paper studied the variations of weed community species composition and spatial heterogeneity in a Zoysia matrella lawn in Guangzhou at different time. The results showed that there were 43 weed species belonging to 19 families in the Z. matrella lawn from 2007 to 2009, in which Gramineae, Compositae, Cyperaceae and Rubiaceae had a comparative advantage. Perennial weeds accounted for the largest proportion of weeds and increased gradually in the three years. Weed communities distributed in higher heterogeneity than in a random model. Dominant weeds varied with season and displayed regularity in the order of 'dicotyledon-monocotyledon-dicotyledon weeds' and 'perennial-annual-perennial weeds'. The spatial heterogeneity of weed community in Z. matrella lawn was higher in summer than in winter. The diversity and evenness of weed community were higher in summer and autumn than in winter and spring. The number of weed species with high heterogeneity in summer was higher than in the other seasons. The spatial heterogeneity and diversity of weed community had no significant change in the three years, while the evenness of weed community had the tendency to decline gradually.

  17. Effect of tillage system on yield and weed populations of soybean ( Glycin Max L.).

    Science.gov (United States)

    Hosseini, Seyed Z; Firouzi, Saeed; Aminpanah, Hashem; Sadeghnejhad, Hamid R

    2016-03-01

    Field experiment was conducted at Agricultural and Natural Resources Research Center of Golestan Province, Iran, to determine the effects of tillage system and weed management regime on yield and weed populations in soybean ( Glycin max L.). The experimental design was a split plot where the whole plot portion was a randomized complete block with three replicates. Main plots were tillage system: 1- No-till row crop seeding, 2- No-till seed drilling, 3- Tillage with disc harrow and drill planting, 4- Tillage with chisel packer and drill planting. The subplots were weed management regimes: 1-Weed control with herbicide application, 2- Hand weeding, 3- Herbicide application plus hand weeding, and 4- Non-weeding. Results indicated that the main effects of tillage system and weed management regime were significant for seed yield, pod number per plant, seed number per pod, weed density and biomass, while their interaction were significant only for weed density, weed biomass, and seed number per pod. The highest grain yields (3838 kg ha-1) were recorded for No-till row crop seeding. The highest seed yield (3877 kg ha-1) also was recorded for weed control with herbicide and hand weeding treatment, followed by hand weeding (3379 kg ha-1).

  18. Efficacy of oxyfluorfen with straw cover in controlling weeds

    OpenAIRE

    Negrisoli, E. [UNESP; Correa, M. R. [UNESP; Rossi, C. V. S. [UNESP; Carbonari, Caio Antonio [UNESP; Velini, Edivaldo Domingues [UNESP; Perim, L. [UNESP

    2009-01-01

    A palha pode alterar a dinâmica do herbicida oxyfluorfen no sistema de cana-crua; assim, este trabalho teve por objetivo avaliar a eficácia do oxyfluorfen em condições de casa de vegetação, com a cobertura de palha, no controle das plantas daninhas que ocorrem em cana-crua. Foram avaliadas as espécies de Brachiaria decumbens, Ipomoea grandifolia, Ipomoea quamoclit e Merremia cissoides. A dose utilizada do oxyfluorfen foi de 3 L ha-1 (720 g i.a. ha-1). Os tratamentos constaram de diferentes po...

  19. Competição de plantas daninhas com a cultura do café em duas épocas de infestação Competition of weeds with coffee plants, in two times of infestation

    Directory of Open Access Journals (Sweden)

    C.M.T. Fialho

    2010-01-01

    Full Text Available Objetivou-se com este trabalho avaliar a interferência de plantas daninhas instaladas aos 60 e aos 180 dias após o transplantio de plantas de café em vasos contendo 25 dm³ de substrato. O experimento foi instalado no delineamento em blocos casualizados, com quatro repetições, em esquema fatorial (2 x 4 x 2, com duas espécies de plantas daninhas (Brachiaria decumbens e Brachiaria plantaginea, cultivadas por 90 dias, em quatro densidades (zero, dois, quatro e seis plantas por vaso, juntamente com mudas de café de diferentes idades: 60 e 180 dias após transplantio. Na colheita do experimento foram avaliados o incremento na altura, na área foliar e no diâmetro do coleto do café, a matéria seca de plantas daninhas e do café e a densidade radicular do café. Estimaram-se, ainda, a razão de massa foliar, a razão de massa caulinar, a razão de massa radicular, a razão de área foliar e a razão sistema radicular/parte aérea das plantas de café. As plantas daninhas proporcionaram interferência negativa nas características avaliadas. Verificou-se menor incremento em altura, área foliar e matéria seca total das plantas de café com o aumento da densidade das plantas daninhas. O efeito da interferência das plantas daninhas foi maior quando a interferência se instalou aos 60 dias após o transplantio. Nesse caso, houve menor acúmulo das variáveis de crescimento, porém as duas gramíneas comportaram-se de forma similar, não diferindo para a maioria das variáveis. As plantas de café foram mais sensíveis à competição com B. plantaginea em relação a B. decumbens quando a competição se instalou aos 180 dias após o transplantio. O aumento da densidade de plantas daninhas promoveu maior alocação de fotoassimilados para a parte aérea em detrimento do sistema radicular do café.The aimed of this work was to evaluate the weed interference installed at 60 and 180 days after coffee seedlings transplanted in pots contend 25 dm

  20. EFFECT OF LEGUME TREES ON SOIL MACROFAUNA OF A Brachiaria brizantha cv. MARANDU PASTURE EFEITO DE LEGUMINOSAS ARBÓREAS SOBRE A MACROFAUNA DO SOLO EM PASTAGEM DE Brachiaria brizantha cv. MARANDU

    Directory of Open Access Journals (Sweden)

    Avílio Antonio Franco

    2007-09-01

    Full Text Available

    The objective of this research was to evaluate the effect of four legume tree species in a Brachiaria brizantha cv. Marandu pasture on soil macrofauna density and diversity, in a low natural fertility soil. The tree leguminous species introduced in the pasture were Pseudosamanea guachapele, Mimosa artemisiana, Mimosa tenuiflora, and Enterolobium contortisiliquum. The macrofauna sampling consisted in collecting six soil monoliths with 25 cm x 25 cm x 30 cm under tree canopies or in a transect in the single Brachiaria pasture. The densities varied from 602 individuals.m-2 under the canopy of E. contortisiliquum to two individuals.m-2 in the single pasture. The largest group richness was found under M. tenuiflora canopy (ten groups, followed by P. guachapele (nine groups, E. contortisiliquum (seven groups and M. artemisiana (six groups. The leguminous species influence was related to N content and to C:N ratio of leaf material. M. artemisiana and M. tenuiflora favored the occurrence of Oligochaeta and Coleoptera larvae, while under the P. guachapele and E. contortisiliquum canopies Formicidae activity was more intense.

    KEY-WORDS: Soil macrofauna; sivipastoral systems; soil quality.

    O objetivou deste trabalho foi avaliar o efeito de quatro espécies leguminosas arbóreas, em uma pastagem de Brachiaria brizantha cv. Marandu, com dois anos de estabelecimento, sobre a densidade e diversidade da macrofauna de um planossolo de baixa fertilidade natural. As espécies arbóreas introduzidas na pastagem foram: Pseudosamanea guachapele, Mimosa artemisiana, Mimosa tenuiflora e Enterolobium contortisiliquum. A amostragem da macrofauna consistiu na retirada de seis monolitos de solo com 25 cm x 25 cm x 30 cm sob a copa das árvores ou em um transecto na pastagem solteira. As densidades variaram de 602

  1. Avaliação de herbicidas de pós-emergência na cultura da batata Evaluation of herbicides on post emergent weed control in potato crops

    Directory of Open Access Journals (Sweden)

    Jeferson Zagonel

    1999-03-01

    Full Text Available O experimento foi instalado na Fazenda Escola da UEPG, Ponta Grossa-PR, em solo Latossolo Vermelho Escuro de textura média argilosa, tendo como objetivo avaliar a eficiência e a seletividade do herbicida propaquizafop no controle pós-emergente de plantas daninhas na cultura da batata. O delineamento experimental foi de blocos ao acaso com seis tratamentos: propaquizafop (100, 125 e 150 g i.a./ha; fluazifop-p-butil (188 g i.a./ha; testemunha capinada e testemunha sem capina, em quatro repetições. O plantio foi realizado em 26 de outubro com a cultivar Elvira, usando-se o espaçamento de 0,70 x 0,35 m. As plantas daninhas presentes foram: Brachiaria plantaginea (capim-papuã, Digitaria horizontalis (capim-milhã e Eleusine indica (capim pé-de-galinha. As avaliações foram efetuadas aos 15, 30 e 45 dias após a aplicação dos tratamento. Observou-se que a aplicação de herbicidas pós-emergentes após a amontoa, permite controle adequado de plantas daninhas desde a emergência até a colheita; o herbicida propaquizafop mostrou-se eficiente no controle sobre capim-papuã e capim pé-de-galinha nas doses de 100, 125 e 150 g i.a./ha e sobre capim-milhã nas doses de 125 e 150 g i.a./ha. As perdas na produção causadas pela competição com plantas daninha foram da ordem de 57,4 %. Não foram observados efeitos fitotóxicos nas plantas de batata que pudessem ser atribuídos aos tratamentos aplicados.The presented field experiment was conducted at the Universidade Estadual de Ponta Grossa, Paraná State, Brazil, on Dark Red Latossoil, to evaluate the efficiency and selectivity of herbicides on post emergence weed control in potato crops. The experiment was laid out in a randomized block design with six treatments and four replications: propaquizafop (100, 125 and 150 g a.i/ha; fluazifop-p-butil (188 g a.i/ha, weed free and weedy. Planting was conducted on October 26, using the cultivar Elvira. Potato plants were spaced 0.70 x 0.35 m. The

  2. Evaluación de la composición bromatológica de 24 accesiones de Brachiaria spp. Evaluation of the bromatological composition of 24 Brachiaria spp. accessions

    Directory of Open Access Journals (Sweden)

    E.R Canchila

    2009-12-01

    Full Text Available Con el objetivo de caracterizar la composición bromatológica de diferentes accesiones e híbridos apomícticos de Brachiaria spp., en condiciones agroecológicas de Barrancabermeja, Santander, Colombia, se evaluaron 24 accesiones de este género. Se utilizó un diseño experimental completamente aleatorizado, en 72 parcelas de 21 m2 cada una y tres réplicas (parcelas para cada tratamiento. Se determinó la MS, la PB, los contenidos de grasa, cenizas y de fibra ácido detergente (FAD. Los contenidos de materia seca oscilaron en un rango de 23,4 a 25,7%; mientras que los de proteína estuvieron entre 5,8 y 7,5%, con los valores más bajos para B. humidicola CIAT-26159 y los más elevados en B. brizantha CIAT-6387y CIAT-26124. A pesar de que no se hallaron variaciones importantes en la composición bromatológica de las accesiones, las especies más promisorias en las condiciones agroecológicas evaluadas fueron: B. híbrido 1873, B. brizantha 16315 y B. brizantha 16488With the objective of characterizing the bromatological composition of different accessions and apomictic hybrids of Brachiaria spp., under the agroecological conditions of Barrancabermeja, Santander, Colombia, 24 accessions of this genus were evaluated. A completely randomized experimental design was used, with 72 plots of 21 m2 each and three replications (plots per treatment. The DM, CP, contents of fat, ash and acid detergent fiber (ADF were determined. The dry matter contents oscillated from 23,4 to 25,7%, while those of crude protein were between 5,8 and 7,5%; with the lowest values for B. humidicola CIAT-26159 and the highest in B. brizantha CIAT-6387 and CIAT-26124. Although no important variations were found in the bromatological composition of the accessions, the most promising species under the evaluated agroecological conditions were: B. híbrido 1873, B. brizantha 16315 and B. brizantha 16488.

  3. Características Agronômicas, Massa de Forragem e Valor Nutritivo de Brachiaria decumbens em Sistema Silvipastoril Agronomics Characteristics, Forage Mass and Nutritional Value of Brachiaria decumbens in a Silvopastoral System

    Directory of Open Access Journals (Sweden)

    Carlos Renato Tavares Castro

    2010-02-01

    Full Text Available

    Avaliaram-se os efeitos de três porcentagens de sombreamento (0, 29% e 45%, proporcionado pelas leguminosas arbóreas Acacia angustissima, A. mangium, A. auriculiformis, Albizia lebbek e Gliricidia sepium, sobre características agronômicas, e o valor nutritivo do pasto de Brachiaria decumbens, durante o inverno, a primavera e o verão. Foi adotado o delineamento experimental de blocos casualizados, com três repetições. O sombreamento influenciou positivamente a massa de forragem, na primavera e no verão. No inverno, a maior massa de forragem foi obtida sob sol pleno. Os teores de proteína bruta aumentaram com o sombreamento, na primavera, mas não se modificaram em função das porcentagens de sombra, no inverno e no verão. Pelo produto da massa de forragem e o teor de proteína bruta, obtiveram-se as quantidades de proteína bruta por área, que foram maiores sob sombreamento mais intenso, na primavera e no verão. Os teores de fibra em detergente neutro e a digestibilidade in vitro da matéria seca não apresentaram tendência consistente com as porcentagens de sombreamento, em função da forte interação deste tratamento com a estação do ano.

     

    doi: 10.4336/2009.pfb.60.19

    The agronomic traits and nutritive value of Brachiaria decumbens pasture were evaluated under three shade percentages (0.29% and 45%, provided by leguminous trees (Acacia angustissima, A. mangium, A. auriculiformis, Albizia lebbek e Gliricidia sepium, during winter, spring and summer seasons. The experimental design was randomized blocks, with three replications. The forage mass was positively influenced by shading, in spring and summer seasons. In winter, the higher forage mass was observed in full sunlight condition. The values of crude protein increased in spring with shading, but did not vary with shade percentage in winter and summer seasons. The crude protein quantity per area, obtained by product between forage mass and crude protein

  4. CALCIUM SOURCE EFFECT ON APPARENT DIGESTIBILITY OF GRASS HAY Brachiaria decumbens Staph cv. Basiliski EFEITO DA FONTE DE CÁLCIO (calcário vs Lithothamnium calcareum NA DIGESTIBILIDADE APARENTE DE CAPIM Brachiaria decumbens Staph cv. Basiliski

    Directory of Open Access Journals (Sweden)

    Deborah Gonçalves Rodrigues

    2007-09-01

    Full Text Available

    An experiment was developed to determine the effect of addition of the marine alga Lithothamnium calcareum in the apparent digestibility of a low quality forage. Twelve adult lambs were kept in metabolical individual cages using a randomly design with three replications and four treatments as follows: I - Brachiaria decumbens grass hay, processed after the seed harvest; II - Hay plus 1000 ppm of calcium from CaCO3 (p.a.; III - Hay plus 1000 ppm of calcium from mineral supplement of alga; IV - Hay plus 2000 ppm of calcium from mineral supplement of alga. The mineral supplement of alga increased the digestibility of crude protein in 7,5% with dosage 1000 ppm and in 12% with dosage of 2000 ppm, when compared with control treatment, but such changes were not significant (P < 0,05. No differences were observed for dry matter and crude fiber.

    Um experimento foi conduzido para determinar o efeito da adição de alga marinha Lithothamnium calcareum na digestibilidade aparente de uma forragem de baixa qualidade. Doze carneiros adultos foram distribuídos em gaiolas metabólicas, inteiramente casualizadas com três repetições. Os tratamentos utilizados foram: I - Feno de capim Brachiaria decumbens, confeccionado após a colheita das sementes; II - Feno mais 1000 ppm de cálcio proveniente do carbonato de cálcio (p.a.; III - Feno mais 1000 ppm de cálcio proveniente do suplemento mineral de alga (L.C. - 400; IV - Feno mais 2000 ppm de cálcio proveniente do suplemento mineral de alga (L.C. - 400. O suplemento mineral aumentou a digestibilidade da proteína bruta em 7,5% na dosagem de 1000 ppm e em l2% na dosagem de 2000 ppm, quando comparados ao tratamento controle, mas tais mudanças não foram significativas (P < 0,05. Não alterou a digestibilidade da matéria seca e fibra bruta.

  5. Isotopes in Weed Research. Proceedings of the Symposium on the Use of Isotopes in Weed Research

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1966-05-15

    The Symposium on the Use of Isotopes in Weed Research was convened jointly by the Food and Agriculture Organization of the United Nations and the International Atomic Energy Agency, and was held in Vienna at the Headquarters of IAEA from 25 to 29 October 1965. It was attended by 67 participants representing 18 countries. The Symposium provided an occasion for the exchange of information on recent advances in the subject. Additionally it gave an opportunity for investigators who had not used isotopes in their research to assess the potentialities and applications of this technique. Isotopes have already been extensively used in weed research, particularly for studying the comparative absorption of herbicides by different plant species and the movement and distribution of the herbicide within the plant. Radioisotopes have proved of particular value in these studies through the ability of autoradiographic techniques to detect even the trace amounts involved. The mode of action of herbicides has also been quite widely studied through the use of isotopes. It is probably a general rule that the practical selective herbicidal nature of a chemical compound is usually known some time before the actual metabolic mode of action is traced. Nevertheless the mode of action is of great importance, as its study may lead to the development of other herbicides; isotope techniques may be expected to play an increasing role here. Weed control is a continuing world agriculture problem of serious dimensions and there is constant effort both to develop and utilize herbicides. As part of the general widespread concern over the residual effects of chemicals applied to crop plants, the study of herbicide residues in plants and soil, and the detoxification of herbicides, has become essential. For these studies isotopic techniques can be usefully used to identify degradation products and trace the ultimate fate of the herbicide. Such studies are of growing importance. Features of the

  6. Isotopes in Weed Research. Proceedings of the Symposium on the Use of Isotopes in Weed Research

    International Nuclear Information System (INIS)

    1966-01-01

    The Symposium on the Use of Isotopes in Weed Research was convened jointly by the Food and Agriculture Organization of the United Nations and the International Atomic Energy Agency, and was held in Vienna at the Headquarters of IAEA from 25 to 29 October 1965. It was attended by 67 participants representing 18 countries. The Symposium provided an occasion for the exchange of information on recent advances in the subject. Additionally it gave an opportunity for investigators who had not used isotopes in their research to assess the potentialities and applications of this technique. Isotopes have already been extensively used in weed research, particularly for studying the comparative absorption of herbicides by different plant species and the movement and distribution of the herbicide within the plant. Radioisotopes have proved of particular value in these studies through the ability of autoradiographic techniques to detect even the trace amounts involved. The mode of action of herbicides has also been quite widely studied through the use of isotopes. It is probably a general rule that the practical selective herbicidal nature of a chemical compound is usually known some time before the actual metabolic mode of action is traced. Nevertheless the mode of action is of great importance, as its study may lead to the development of other herbicides; isotope techniques may be expected to play an increasing role here. Weed control is a continuing world agriculture problem of serious dimensions and there is constant effort both to develop and utilize herbicides. As part of the general widespread concern over the residual effects of chemicals applied to crop plants, the study of herbicide residues in plants and soil, and the detoxification of herbicides, has become essential. For these studies isotopic techniques can be usefully used to identify degradation products and trace the ultimate fate of the herbicide. Such studies are of growing importance. Features of the

  7. Tillage and residue burning affects weed populations and seed banks.

    Science.gov (United States)

    Narwal, S; Sindel, B M; Jessop, R S

    2006-01-01

    An integrated weed management approach requires alternative management practices to herbicide use such as tillage, crop rotations and cultural controls to reduce soil weed seed banks. The objective of this study was to examine the value of different tillage practices and stubble burning to exhaust the seed bank of common weeds from the northern grain region of Australia. Five tillage and burning treatments were incorporated in a field experiment, at Armidale (30 degrees 30'S, 151 degrees 40'E), New South Wales, Australia in July 2004 in a randomized block design replicated four times. The trial was continued and treatments repeated in July 2005 with all the mature plants from the first year being allowed to shed seed in their respective treatment plots. The treatments were (i) no tillage (NT), (ii) chisel ploughing (CP), (iii) mould board ploughing (MBP), (iv) wheat straw burning with no tillage (SBNT) and (v) wheat straw burning with chisel ploughing (SBC). Soil samples were collected before applying treatments and before the weeds flowered to establish the seed bank status of the various weeds in the soil. Wheat was sown after the tillage treatments. Burning treatments were only initiated in the second year, one month prior to tillage treatments. The major weeds present in the seed bank before initiating the trial were Polygonum aviculare, Sonchus oleraceus and Avena fatua. Tillage promoted the germination of other weeds like Hibiscus trionum, Medicago sativa, Vicia sp. and Phalaris paradoxa later in the season in 2004 and Convolvulus erubescens emerged as a new weed in 2005. The MBP treatment in 2004 reduced the weed biomass to a significantly lower level of 55 g/m2 than the other treatments of CP (118 g/m2) and NT plots (196 g/m2) (P < 0.05). However, in 2005 SBC and MBP treatments were similar in reducing the weed biomass. In 2004, the grain yield trend of wheat was significantly different between CP and NT, and MBP and NT (P < 0.05) with maximum yield of 5898

  8. Effect of doses of poultry compost on chorophyll and flavonoids of Brachiaria brizantha brs Piatã

    Directory of Open Access Journals (Sweden)

    Alexandre Antonio Pasqualini

    2013-12-01

    Full Text Available In 2012, Brazil produced 12.6 million metric tons of chicken meat, generating 10.3 tons of poultry litter. Compost made from such organic waste can be used as a low-cost bio fertilizer, especially as nitrogen and phosphorus source. The compost can increase pastures quality by giving photosynthetic improvement and altering amounts of chlorophyll and flavonoids.  There is little information about the relationship between chlorophyll a or b and flavonoids in Brachiaria brizantha Piata. The flavonoid is a kind of polyphenol compound which protects the plant against UV-B radiation and pathogen attack, it acts as attractants for pollinators, as signal molecules for initiating plant-microbe symbiotic associations and antioxidant activity. The objective of the present study was verified the effects of poultry litter compost doses on the chlorophyll and flavonoid contents in Piata grass leaves. The experiment was performed at the Animal Nutrition and Pasture Center – Instituto de Zootecnia – Nova Odessa, SP, from May to July 2013, on a Haplorthox soil (pHCaCl2= 4.9, cultivated with Piata grass (Brachiaria brizantha, Stapf, without liming. The treatments consisted of five compost doses: 0; 20; 40; 60 and 120 Mg ha-1, with the following chemical composition (%: 2.88 of N, 3.85 of P2O5, 2.50 of K2O, 9.06 of Ca and 1.16 of Mg. The experimental design was on randomized blocks with five replications.  Chlorophyll amounts and flavonoids were determined by sampling the third medium of the leaf blade from  a third of the expanded leaf from the apical  using the Dualex and the chlorophyll a and b  which were determined by  the Lichtenthaler & Wellburn (1983 method.  Results showed that chlorophyll a was similar in all doses (average of 18.3 micrograms per cm2,therefore for chlorophyll b the amount was significantly increased from 7.3 to 22.4 micrograms per  cm2 (P<0.01when compared to no addition of poultry litter. The fast nitrogen liberation from

  9. Adjustment of Weed Hoeing to Narrowly Spaced Cereals

    Directory of Open Access Journals (Sweden)

    Jannis Machleb

    2018-04-01

    Full Text Available Weed hoeing can be successfully performed in wide row crops, such as sugar beet, maize, soybean and wide spaced cereals. However, little experience is available for hoeing in narrow cereal row spaces below 200 mm. Yet, mechanical weed control can pose an alternative to herbicide applications by reducing the herbicide resistant populations present in the field. In this experiment, it was investigated whether hoeing is feasible in cereals with 150 and 125 mm row spacings. The trial was set up at two locations (Ihinger Hof and Kleinhohenheim in southwest Germany. Three different conventional hoeing sweeps, a goosefoot sweep, a no-till sweep and a down-cut side knife were adjusted to the small row widths, and hoeing was performed once with a tractor and a standard hoeing frame which was guided by a second human operator. The average grain yield, crop and weed biomass, and weed control efficacy of each treatment were recorded. The goosefoot and no-till sweep were tested at driving speeds of 4 and 6 km·h−1. The down-cut side knife was applied at 4 km·h−1. The results indicate that hoeing caused no yield decrease in comparison to a conventional herbicide application or manual weeding. The highest yield with a mechanical treatment was recorded for the no-till sweeps at both trial locations. Hoeing was performed successfully in narrowly spaced cereals of 150 and 125 mm, and the weed control efficacy of the mechanical treatments ranged from 50.9% at Kleinhohenheim to 89.1% at Ihinger Hof. Future experiments are going to focus on more distinct driving speeds ranging from 2 to 10 km·h−1 and performing more than one pass with the hoe. Additionally, combining the mechanical weeding tools with a camera-steered hoeing frame could increase accuracy, allow for higher working speeds and substitute the second human operator guiding the hoe.

  10. Assessment of Corn Densities on Ecological Indices of Weed Species

    Directory of Open Access Journals (Sweden)

    G Mahmoodi

    2012-06-01

    Full Text Available Diversity, dominance, and stability of weeds are the most important ecological properties in agricultural systems, which influenced by management factors such as crop density, abundantly. This experiment was conducted in 2009 at Ferdowsi University of Mashhad Research Field. The experimental design was interval mapping with four levels of corn densities (5, 6, 7 and 9 plant.m-2 and four levels of weed control (full-control, without control, broad-leaves control and grasses control. Weed sampling was done at 3 stages included beginning and end of critical period weed control and harvesting time. The results showed that the effect of plant density on species diversity was significant; some how the amount of Shanon and Simpson Indices were lowest in the 9 plant.m-2 (0.39 and 0.45, respectively and greatest in 5 plant.m-2 (0.84. The results also showed that the maximum amount of dominance index was observed in 9 plant.m-2, that was seen in Echinochloa crus- galli and Convulvulus arvensis at the beginning of growing season, then in Solanum nigrum and Amaranthus retroflexus in the end of growing season. The amount of community dominance index in 9 plant.m-2 was higher than other densities, and it decreased with decline of densities. based on the results of present experiment the linear relationship between plant species and area was found. The calculated amount of Alpha and Beta diversities. in a θ and β scales based on coefficients of this relationship were 0.534 (four species per unit area and 0.29 (two species per unit area, respectively. In conclusion the result of this experiment pointed that the weeds diversity decreased with increasing of corn density, weed diversity decreased and therefore, having appropriate plant density is very efficient for sustainable weed management.

  11. Allelopathic assessment of selected common weeds in Malaysia

    Science.gov (United States)

    Nurul Ain, M. B.; Nornasuha, Y.; Ismail, B. S.

    2016-11-01

    A laboratory study was conducted to evaluate the allelopathic potential of eight common weed species in Malaysia, namely, Ageratum conyzoides, Tridax procumbens, Cyperus iria, Fimbristylis miliacea, Eleusine indica, Imperata cylindrica, Lygodium flexuosum and Nephrolepis biserrata of different morphological characteristics (broadleaves, sedges, grasses and ferns). The allelopathic study of these weeds was carried out by testing the leaf litter leachate through the Sandwich method and the volatile compounds of these weeds through the Dish pack method with three replicates for each donor species. The results obtained from both methods were statistically analyzed and the means had converted to percentage growth inhibition to determine the inhibition pattern on the radicle and hypocotyl growth of lettuce seedlings. Among the eight weed species tested, Ageratum conyzoides showed the strongest growth inhibition on lettuce radicle elongation (86%) in the sandwich bioassay compared to the control, followed by Tridax procumbens (71%), which both species being broadleaves weeds. In the dish pack bioassay Lygodium flexuosum (fern) demonstrated maximum inhibition on the growth the radicle and hypocotyl for each different distance from the source well. On the other hand, two weed species exhibited enhanced on the growth radicle and hypocotyl when compared to that of the control in dish pack bioassay. Nephrolepis biserrata and Fimbristylis miliacea were the species that showed the highest growth stimulatory effect. The results presented can be utilized as benchmark information for further research on the elucidation of leachates and volatile chemicals involved in allelopathy in nature. The information can also be helpful in the development of new bioactive chemicals from natural products in weed control strategies.

  12. Natural metabolites for parasitic weed management.

    Science.gov (United States)

    Vurro, Maurizio; Boari, Angela; Evidente, Antonio; Andolfi, Anna; Zermane, Nadjia

    2009-05-01

    Compounds of natural origin, such as phytotoxins produced by fungi or natural amino acids, could be used in parasitic weed management strategies by interfering with the early growth stages of the parasites. These metabolites could inhibit seed germination or germ tube elongation, so preventing attachment to the host plant, or, conversely, stimulate seed germination in the absence of the host, contributing to a reduction in the parasite seed bank. Some of the fungal metabolites assayed were very active even at very low concentrations, such as some macrocyclic trichothecenes, which at 0.1 microM strongly suppressed the germination of Orobanche ramosa L. seeds. Interesting results were also obtained with some novel toxins, such as phyllostictine A, highly active in reducing germ tube elongation and seed germination both of O. ramosa and of Cuscuta campestris Yuncker. Among the amino acids tested, methionine and arginine were particularly interesting, as they were able to suppress seed germination at concentrations lower than 1 mM. Some of the fungal metabolites tested were also able to stimulate the germination of O. ramosa seeds. The major findings in this research field are described and discussed.

  13. Control of invasive weeds with prescribed burning

    Science.gov (United States)

    DiTomaso, Joseph M.; Brooks, Matthew L.; Allen, Edith B.; Minnich, Ralph; Rice, Peter M.; Kyser, Guy B.

    2006-01-01

    Prescribed burning has primarily been used as a tool for the control of invasive late-season annual broadleaf and grass species, particularly yellow starthistle, medusahead, barb goatgrass, and several bromes. However, timely burning of a few invasive biennial broadleaves (e.g., sweetclover and garlic mustard), perennial grasses (e.g., bluegrasses and smooth brome), and woody species (e.g., brooms and Chinese tallow tree) also has been successful. In many cases, the effectiveness of prescribed burning can be enhanced when incorporated into an integrated vegetation management program. Although there are some excellent examples of successful use of prescribed burning for the control of invasive species, a limited number of species have been evaluated. In addition, few studies have measured the impact of prescribed burning on the long-term changes in plant communities, impacts to endangered plant species, effects on wildlife and insect populations, and alterations in soil biology, including nutrition, mycorrhizae, and hydrology. In this review, we evaluate the current state of knowledge on prescribed burning as a tool for invasive weed management.

  14. Weed Diversity Affects Soybean and Maize Yield in a Long Term Experiment in Michigan, USA.

    Science.gov (United States)

    Ferrero, Rosana; Lima, Mauricio; Davis, Adam S; Gonzalez-Andujar, Jose L

    2017-01-01

    Managing production environments in ways that promote weed community diversity may enhance both crop production and the development of a more sustainable agriculture. This study analyzed data of productivity of maize (corn) and soybean in plots in the Main Cropping System Experiment (MCSE) at the W. K. Kellogg Biological Station Long-Term Ecological Research (KBS-LTER) in Michigan, USA, from 1996 to 2011. We used models derived from population ecology to explore how weed diversity, temperature, and precipitation interact with crop yields. Using three types of models that considered internal and external (climate and weeds) factors, with additive or non-linear variants, we found that changes in weed diversity were associated with changes in rates of crop yield increase over time for both maize and soybeans. The intrinsic capacity for soybean yield increase in response to the environment was greater under more diverse weed communities. Soybean production risks were greatest in the least weed diverse systems, in which each weed species lost was associated with progressively greater crop yield losses. Managing for weed community diversity, while suppressing dominant, highly competitive weeds, may be a helpful strategy for supporting long term increases in soybean productivity. In maize, there was a negative and non-additive response of yields to the interaction between weed diversity and minimum air temperatures. When cold temperatures constrained potential maize productivity through limited resources, negative interactions with weed diversity became more pronounced. We suggest that: (1) maize was less competitive in cold years allowing higher weed diversity and the dominance of some weed species; or (2) that cold years resulted in increased weed richness and prevalence of competitive weeds, thus reducing crop yields. Therefore, we propose to control dominant weed species especially in the years of low yield and extreme minimum temperatures to improve maize yields

  15. Emerging Challenges and Opportunities for Education and Research in Weed Science

    Directory of Open Access Journals (Sweden)

    Bhagirath S. Chauhan

    2017-09-01

    Full Text Available In modern agriculture, with more emphasis on high input systems, weed problems are likely to increase and become more complex. With heightened awareness of adverse effects of herbicide residues on human health and environment and the evolution of herbicide-resistant weed biotypes, a significant focus within weed science has now shifted to the development of eco-friendly technologies with reduced reliance on herbicides. Further, with the large-scale adoption of herbicide-resistant crops, and uncertain climatic optima under climate change, the problems for weed science have become multi-faceted. To handle these complex weed problems, a holistic line of action with multi-disciplinary approaches is required, including adjustments to technology, management practices, and legislation. Improved knowledge of weed ecology, biology, genetics, and molecular biology is essential for developing sustainable weed control practices. Additionally, judicious use of advanced technologies, such as site-specific weed management systems and decision support modeling, will play a significant role in reducing costs associated with weed control. Further, effective linkages between farmers and weed researchers will be necessary to facilitate the adoption of technological developments. To meet these challenges, priorities in research need to be determined and the education system for weed science needs to be reoriented. In respect of the latter imperative, closer collaboration between weed scientists and other disciplines can help in defining and solving the complex weed management challenges of the 21st century. This consensus will provide more versatile and diverse approaches to innovative teaching and training practices, which will be needed to prepare future weed science graduates who are capable of handling the anticipated challenges of weed science facing in contemporary agriculture. To build this capacity, mobilizing additional funding for both weed research and

  16. Weed Competition and its Effects on Pwani Hybrid 1 Maize Grain Yields in Coastal Kenya

    International Nuclear Information System (INIS)

    Kamau, G.M.; Saha, H.M.

    1999-01-01

    Weed competition is a serious constraint to maize production in coastal Kenya. A trial to asses the effects of weed competition on performance of maize was planted at Regional Research Centre-Mtwapa and Msabaha Research Sub-centre-Malindi in 1992. Pwani hybrid 1 maize was used in the trials. Weeding was done at weekly intervals from germination up to the sixth week in an additive weed removal system and plots maintained weed free afterwards. A weedy and a weed free plot were used as checks. Data on plant counts plant heights, weed biomass, weed identification and maize grain yield at 15 % MC were all recorded. There was a significant difference between weed and weedy free plots for grain yield, plant height and weed biomass for both sites. A 53% maize grain yield reduction due to weed competition was recorded. A 3% grain yield reduction equivalent to 1.03 bags for every week's delay in weeding after the first to weeks was realised for both sites. There was a corresponding grain yield loss as delay in weeding increased

  17. Rendimiento y calidad fisiológica de la semilla de Brachiaria spp. en los llanos colombianos

    Directory of Open Access Journals (Sweden)

    Sánchez O. M.

    1996-12-01

    Full Text Available

    186 accessions of 9 species of Brachiaria were established in a design of fringes divided on 2 repetitions. In the third year seeds were evaluated to test their potencial under 2 different fertility levels: a One recommended in order to establish pastures; b Other in order to establish a system composed rice-pasture. The yield and the seed weight unit did not present significant differences (P<0.05 in the utilization of one or another level of fertility. The viability test at 11 and 14 mpc showed that B. humidicola had the higher viability, while B. brizantha have the lower value at 11 mpc and B. dictyoneura at 14 mpc. The germination and dormancy tests evaluated the effect of 2 treatments: 1 Water and 2 Scarification seeds with sulphuric acid or with potassium nitrate for the case of B. humidicola. B. humidicola had the best germination at 11mpc, while B. dictyoneura reached the highest germination percentage at 14 mpc.

    186 accesiones de 9 especies de Brachiaria, se establecieron en un diseño de franjas divididas, con 2 repeticiones, para evaluar 2 niveles de fertilidad: a el recomendado para establecer pasturas; b el nivel para establecer un sistema integrado arroz-pastos. En el tercer año se evaluó el potencial de rendimiento de semillas. En las pruebas de germinación y latencia se evaluó el efecto de 2 tratamientos: 1 Agua y 2 Semilla escarificada en ácido sulfúrico; las de b. humidicola se trataron con Nitrato de Potasio. El rendimiento promedio y el Peso Unidad de las semillas no presentaron diferencias significativas (P<0.05 por efecto del nivel de fertilidad. Las semillas de B. decumbens, sin tratamiento, germinaron 0.3% a los 11 meses y se incrementó a 38.3% cuando se escarificaron; B. dictyoneura alcanzó la mayor germinación (69.3% a los 14 meses, y B. humidicola (52.1% a los 11meses. En B. brizantha y B. jubata se presentaron incrementos de 32.8 y 21.3% respectivamente, a los 14 meses.

  18. Effects of Grazing Management in Brachiaria grass-forage Peanut Pastures on Canopy Structure and Forage Intake.

    Science.gov (United States)

    Gomes, F K; Oliveira, M D B L; Homem, B G C; Boddey, R M; Bernardes, T F; Gionbelli, M P; Lara, M A S; Casagrande, D R

    2018-06-13

    Maintenance of mixed grass-legume pastures for stand longevity and improved animal utilization is a challenge in warm-season climates. The goal of this study was to assess grazing management on stand persistence, forage intake, and N balance of beef heifers grazing mixed pastures of Brachiaria brizantha and Arachis pintoi. A two-year experiment was carried out in Brazil, where four grazing management were assessed: rest period interrupted at 90%, 95%, and 100% of light interception (LI) and a fixed rest period of 42 days (90LI, 95LI, 100LI, and 42D, respectively). The LI were taken at 50 points at ground level and at five points above the canopy for each paddock using a canopy analyzer. For all treatments, the post-grazing stubble height was 15 cm. Botanical composition and canopy structure characteristics such as canopy height, forage mass, and vertical distribution of the morphological composition were evaluated pre-and post-grazing. Forage chemical composition, intake, and microbial synthesis were also determined. A randomized complete block design was used, considering the season of the year as a repeated measure over time. Grazing management and season were considered fixed, while block and year were considered random effects. In the summer, legume mass accounted for 19% of the canopy at 100LI, which was less than other treatments (a mean of 30%). The 100LI treatment had a greater grass stem mass compared with other treatments. In terms of vertical distribution for 100LI, 38.6% of the stem mass was above the stubble height, greater than the 5.7% for other treatments. The canopy structure limited neutral detergent fiber intake (P = 0.007) at 100LI (1.02% of BW/d), whereas 42D, 90LI, and 95LI treatments had NDF intake close to 1.2% of BW/d. The intake of digestible organic matter (OM; P = 0.007) and the ratio of crude protein/digestible OM (P < 0.001) were less at 100LI in relation to the other treatments. The production of microbial N (P < 0.001) and efficiency

  19. Influência do tipo e da quantidade de resíduos vegetais na emergência de plantas daninhas Influence of type and amount of crop residues on weed emergence

    Directory of Open Access Journals (Sweden)

    N.M. Correia

    2006-06-01

    Full Text Available Com o objetivo de avaliar os efeitos da semeadura no outono/inverno de diferentes espécies: sorgo de cobertura (Sorghum bicolor x Sorghum sudanense 'híbrido Cober Exp', milheto forrageiro (Pennisetum americanum 'var. BN2', capim-pé-de-galinha (Eleusine coracana e braquiária (Brachiaria brizantha para formação de palha (nas quantidades de 3,0 e 5,5 t ha¹, na emergência de plantas daninhas, foi conduzido experimento no ano agrícola 2003/04, na fazenda Três Marcos, em Uberlândia, MG. Foi mantida uma testemunha como tratamento adicional, sem cobertura com restos vegetais. A composição específica e as densidades populacionais das comunidades infestantes foram influenciadas pelos sistemas de produção de cobertura morta. A emergência das plantas daninhas foi menor nas coberturas de sorgo e braquiária e nos maiores níveis de palha. O número de plântulas emergidas de Bidens pilosa, Amaranthus spp., Commelina benghalensis, Leucas martinicensis e gramíneas foi inibido pelas coberturas, enquanto para Chamaesyce spp. os resíduos contribuíram para incremento na sua emergência.To evaluate the effects on weed emergence of autumn/winter sowing of different species [sorghum (Sorghum bicolor x Sorghum sudanense 'Cober Exp hybrid', forage millet (Pennisetum americanum 'var. BN2', finger millet (Eleusine coracana and St Lucia grass (Brachiaria brizantha, for mulch formation (at rates of 3.0 and 5.5 t ha-1, an experiment was carried out in the agricultural year 2003/2004, in Uberlândia, Minas Gerais, Brazil. The specific composition and population densities of the infesting community were influenced by the mulch production systems. Weed emergence was minor under sorghum and Sta Lucia grass cover and in greater amounts of straw. Straw cover inhibited the emergence of seedlings of Bidens pilosa, Amaranthus spp., Commelina benghalensis, Leucas martinicensis and grasses and stimulated the emergence of Chamaesyce spp.

  20. Crescimento de espécies do gênero Brachiaria, sob déficit hídrico, em casa de vegetação Effect of water deficit on the growth of Brachiaria species in greenhouse

    Directory of Open Access Journals (Sweden)

    Jorge Luiz Schirmer de Mattos

    2005-06-01

    Full Text Available Avaliaram-se as características morfogênicas, fisiológicas e produtivas de espécies de Brachiaria, durante e após período de estresse hídrico. Os tratamentos foram arranjados em um esquema fatorial 4 x 5 quatro espécies de Brachiaria (B. decumbens, B. brizantha, B. humidicola e B. mutica e cinco níveis de potencial hídrico do solo (-0, 01, -0, 03, -0, 1, -0, 5 e -1, 5 MPa em um delineamento experimental de blocos ao acaso, com três repetições. O experimento foi instalado em casa de vegetação, em colunas de PVC com 40 cm de altura e 30 cm de diâmetro. Os déficits hídricos foram impostos durante 23 dias e, após este período, um grupo de plantas foi mantido sob condições normais de disponibilidade de água no solo, durante, aproximadamente, uma semana, para se avaliar a capacidade de recuperação das plantas. A taxa de alongamento das lâminas foliares foi comprometida em B. brizantha e a taxa de senescência de lâminas foliares em B. mutica foi aumentada com o decréscimo do potencial hídrico no solo, denotando a maior sensibilidade destas duas espécies ao déficit hídrico. Observou-se controle estomático sobre as trocas gasosas em folhas de todas as espécies. O déficit hídrico reduziu a fotossíntese líquida em todas espécies, mais acentuadamente em B. mutica e B. humidicola. Todas as espécies recuperaram suas atividades fotossintéticas normais após o déficit hídrico, mas apenas a B. brizantha restabeleceu o status hídrico de seus tecidos foliares. O déficit hídrico afetou mais acentuadamente a área de lâminas foliares verdes em B. brizantha e B. decumbens, a produção de matéria verde seca de lâminas foliares em todas as espécies estudadas, e a produção de matéria verde seca de colmos em B. decumbens e B. mutica.This study aimed to evaluate the tolerance of Brachiaria species (B. decumbens, B. brizantha, B. humidicola and B. mutica to low soil water potential. Morphogenetical, physiological and

  1. Características estruturais e índice de tombamento de Brachiaria decumbens cv. Basilisk em pastagens diferidas Structural characteristics and falling index of Brachiaria decumbens cv. Basilisk on deferred pastures

    Directory of Open Access Journals (Sweden)

    Manoel Eduardo Rozalino Santos

    2009-04-01

    Full Text Available Objetivou-se avaliar o efeito dos períodos de diferimento e de pastejo sobre a densidade populacional de perfilhos, a massa dos componentes morfológicos da forragem e o índice de tombamento em pastagens de Brachiaria decumbens cv. Basilisk. Dois ensaios foram conduzidos: o primeiro denominado ano 1 e, o segundo, ano 2. Adotou-se o esquema de parcelas subdivididas, segundo o delineamento em blocos casualizados, com duas repetições para cada combinação dos períodos de diferimento da pastagem com os períodos de pastejo. No ano 1, os períodos de diferimento foram 103, 121, 146 e 163 dias; e no ano 2, foram 73, 103, 131 e 163 dias. Os períodos de pastejo foram 1, 29, 57 e 85 dias. O aumento do período de diferimento elevou a densidade populacional de perfilhos reprodutivos (ano 2: de 37 para 304 perfilhos/m² e reduziu a de perfilhos vegetativos (ano 1: de 1.253 para 889 perfilhos/m²; ano 2: de 1.235 para 627 perfilhos/m². Durante o período de pastejo, ocorreu diminuição no número de perfilhos vegetativo (ano 1: de 988 para 868 perfilhos/m² e reprodutivo (ano 1: de 216 para 0 perfilhos/m²; ano 2: de 203 para 0 perfilhos/m² e aumento no número de perfilhos mortos (ano 1: 463 para 1.088 perfilhos/m²; ano 2: de 341 para 1.010 perfilhos/m². Pastagens sob maiores períodos de diferimento e de pastejo apresentaram maior massa de colmo morto (6.093 e 3.819 kg/ha de MS nos anos 1 e 2, respectivamente e menor massa de lâmina foliar verde (341 e 177 kg/ha de MS nos anos 1 e 2, respectivamente. Pastos de Brachiaria decumbens cv. Basilisk, submetidos a longos períodos de diferimento e de pastejo possuem características estruturais desfavoráveis à produção animal.This worked aimed to evaluate the effects of deferring and grazing periods on the tiller population density, morphological component mass of forage and falling index on Brachiaria decumbens cv. Basilisk pastures. Two assays were carried out: first year and second year

  2. Desempenho de pontas de pulverização em Brachiaria brizantha cv. MG-4 para controle de ninfas de cigarrinhas das pastagens Spray nozzles performance in Brachiaria brizantha cv. MG-4 for pastures spittlebugs nymphs control

    Directory of Open Access Journals (Sweden)

    Cleber D. de G. Maciel

    2007-01-01

    Full Text Available O trabalho teve como objetivo estudar o desempenho de pontas de pulverização na deposição da calda inseticida para o controle de ninfas de cigarrinhas das pastagens em Brachiaria brizantha cv. MG-4. Doze tratamentos foram estudados em esquema fatorial 6x2, constituídos pelo contraste de seis pontas de pulverização e pressões de 196 e 392 kPa: TF-VP2 (336 L ha-1 e 467 L ha-1; AI11002-VS (184 L ha-1 e 200 L ha-1; XR11002-VS (200 L ha-1 e 280 L ha-1; TT11002-VP (200 L ha-1 e 280 L ha-1; TJ60-11002VS (208 L ha-1 e 280 L ha-1 e TX-VK4 (72 L ha-1 e 97 L ha-1. Para monitorar a deposição das caldas de pulverização, utilizaram-se os traçadores Azul Brilhante FD&C-1 (0,3% p/v e Amarelo de Tartrasina FD&C-5 (0,6% p/v. Alvos artificiais, constituídos de lâminas de vidro, foram posicionados na base das plantas, próximos à superfície do solo, e os depósitos por unidade de área das soluções pulverizadas foram quantificados por espectrofotometria. As pontas TF-VP2, XR11002-VS e AI11002-VS, nas pressões de 196 e 392 kPa, proporcionam as maiores deposições da calda de pulverização na região das espumas das cigarrinhas das pastagens, apesar de apresentarem menor uniformidade na distribuição dos depósitos em relação a TX-VK4, XR110.02-VS e TJ110.02-VS. O aumento da pressão de 196 para 392 kPa promoveu aumento na deposição da calda de pulverização sobre a Brachiaria brizantha e na região onde se encontram as espumas das cigarrinhas para todos os tipos de pontas estudadas.The work aimed to study spray nozzles performance in pesticide sprayer deposition for controlling pastures spittlebugs nymphs in Brachiaria brizantha cv. MG-4 pasture. Twelve treatments were studied in factorial scheme 6x2, constituted by the contrast of six spray nozzles and 196 and 392 kPa work pressures: TF-VP2 (336 L ha-1 and 467 L ha-1; AI11002-VS (184 L ha-1 and 200 L ha-1; XR11002-VS (200 L ha-1 and 280 L ha-1; TT11002-VP (200 L ha-1 and 280 L ha¹; TJ60

  3. Eficácia e seletividade de herbicidas do grupo das imidazolinonas aplicados em pós-emergência de plantas daninhas monocotiledôneas na cultura do girassol CL Efficacy and selectivity of herbicides from the imidazolinone group applied in post-emergence of monocotyledon weeds on CL sunflower culture

    Directory of Open Access Journals (Sweden)

    A.C. Francischini

    2012-12-01

    Full Text Available O controle das plantas daninhas, em geral, é realizado pelo uso de herbicidas, porém essa prática é limitada na cultura do girassol, por haver apenas dois produtos registrados para essa cultura (alachlor e trifluralin. Entretanto, o uso de novas tecnologias pode facilitar o controle das plantas daninhas com herbicidas que possuem amplo espectro de controle. Assim, o objetivo deste trabalho foi avaliar a eficácia e seletividade de herbicidas do grupo das imidazolinonas aplicados em pós-emergência de plantas daninhas monocotiledôneas na cultura do girassol Clearfield (CL. Para isso, foram instalados dois experimentos em campo. Os tratamentos e as respectivas doses em g ha-1 foram: trifluralin (1.800 aplicado em pré-emergência, fluazifop-p-butil (187 e imazapic+imazapyr nas doses de [36,75+12,25], [52,5+17,5], [12,25+36,75] e [17,5+52,5], aplicados em pós-emergência, além de duas testemunhas sem aplicação de herbicida, sendo uma sem capina e outra com capina. Foram realizadas avaliações de controle para Eleusine indica, Brachiaria plantaginea, Lolium multiflorum, Digitaria insularis, Cenchrus echinatus e Digitaria horizontalis, fitointoxicação do girassol Clearfield, estande e produtividade em kg ha-1. De acordo com os resultados, verificou-se que o uso do sistema CLmostrou-se uma ótima opção para áreas com infestação de plantas daninhas monocotiledôneas, pois possibilita a aplicação de herbicidas inibidores da enzima acetolactato sintase (ALS, obtendo excelente controle das plantas daninhas, além de não provocar injúrias visuais, mantendo o estande inicial, sem alterar a produtividade da cultura.Weed control is generally accomplished by the use of herbicides. However, this practice is limited in sunflower cultivation,since only two products are registered for the culture (alachlor and trifluralin.The use of new technologies can facilitate weed control with herbicides with broad spectrum control. Therefore, the

  4. The weeding handbook a shelf-by-shelf guide

    CERN Document Server

    Vnuk, Rebecca

    2015-01-01

    "No! We can't rid of that!" Vnuk, author of the popular "Weeding Tips" column on Booklist Online, is here to show you that yes, you can. A library is an ever-changing organism; when done the right way, weeding helps a library thrive by focusing its resources on those parts of the collection that are the most useful to its users. Her handbook takes the guesswork out of this delicate but necessary process, giving public and school library staff the knowledge and the confidence to effectively weed any collection, of any size. Going through the proverbial stacks shelf by shelf, Vnuk: Explains why weeding is important for a healthy library, demonstrating that a vibrant collection leads to robust circulation, which in turn affects library budgets Walks readers through a library's shelves by Dewey area, with recommended weeding criteria and call-outs in each area for the different considerations of large collections and smaller collections Features a chapter addressing reference, media, magazines and newspapers, e-b...

  5. Cruciferous weeds in oil seed rape – appearance and control

    Directory of Open Access Journals (Sweden)

    Klingenhagen, Günter

    2014-02-01

    Full Text Available Different cruciferous weeds were drilled in autumn 2011 and 2012 in a field near Münster. Beside common species like hedge mustard (Sisymbrium officinale Scop., shepherd`s purse (Capsella bursa-pastoris, pennycress (Thlaspiarvense, tall hedge mustard (Sisymbrium loeselii and flixweed (Descurainia sophia, we tried to establish weeds that are not common on arable land in Germany until now. These were: Yellow rocket (Barbarea vulgaris, hoary cress (Lepidium draba and Turkish rocket (Bunias orientalis. In autumn 2011 emergence of the sown weeds was poor. In the second year of experiment we got good emergence of the named weeds excluding hoary cress (Lepidium draba. In autumn 2011 and 2012 different herbicidecombinations were applied across the stripes. The best results were achieved with Colzor Trio (clomazone + dimethachlor + napropamid which was applied in pre-emergence state, a spray sequence Butisan Gold (metazachlor + quinmerac + dimethenamid-P applied in pre-emergence followed by Salsa (ethametsulfuronmethyl + Trend (adjuvant in post-emergence and Clearfield-Vantiga (metazachlor + quinmerac + imazamox + Dash (adjuvant, also applied in post-emergence state of the weeds.

  6. Weed Growth Stage Estimator Using Deep Convolutional Neural Networks.

    Science.gov (United States)

    Teimouri, Nima; Dyrmann, Mads; Nielsen, Per Rydahl; Mathiassen, Solvejg Kopp; Somerville, Gayle J; Jørgensen, Rasmus Nyholm

    2018-05-16

    This study outlines a new method of automatically estimating weed species and growth stages (from cotyledon until eight leaves are visible) of in situ images covering 18 weed species or families. Images of weeds growing within a variety of crops were gathered across variable environmental conditions with regards to soil types, resolution and light settings. Then, 9649 of these images were used for training the computer, which automatically divided the weeds into nine growth classes. The performance of this proposed convolutional neural network approach was evaluated on a further set of 2516 images, which also varied in term of crop, soil type, image resolution and light conditions. The overall performance of this approach achieved a maximum accuracy of 78% for identifying Polygonum spp. and a minimum accuracy of 46% for blackgrass. In addition, it achieved an average 70% accuracy rate in estimating the number of leaves and 96% accuracy when accepting a deviation of two leaves. These results show that this new method of using deep convolutional neural networks has a relatively high ability to estimate early growth stages across a wide variety of weed species.

  7. Controlling weeds with fungi, bacteria and viruses: a review

    Science.gov (United States)

    Harding, Dylan P.; Raizada, Manish N.

    2015-01-01

    Weeds are a nuisance in a variety of land uses. The increasing prevalence of both herbicide resistant weeds and bans on cosmetic pesticide use has created a strong impetus to develop novel strategies for controlling weeds. The application of bacteria, fungi and viruses to achieving this goal has received increasingly great attention over the last three decades. Proposed benefits to this strategy include reduced environmental impact, increased target specificity, reduced development costs compared to conventional herbicides and the identification of novel herbicidal mechanisms. This review focuses on examples from North America. Among fungi, the prominent genera to receive attention as bioherbicide candidates include Colletotrichum, Phoma, and Sclerotinia. Among bacteria, Xanthomonas and Pseudomonas share this distinction. The available reports on the application of viruses to controlling weeds are also reviewed. Focus is given to the phytotoxic mechanisms associated with bioherbicide candidates. Achieving consistent suppression of weeds in field conditions is a common challenge to this control strategy, as the efficacy of a bioherbicide candidate is generally more sensitive to environmental variation than a conventional herbicide. Common themes and lessons emerging from the available literature in regard to this challenge are presented. Additionally, future directions for this crop protection strategy are suggested. PMID:26379687

  8. New possibilities for weed control in conventional soybeans

    Directory of Open Access Journals (Sweden)

    Petersen, Jan

    2014-02-01

    Full Text Available In field trials in was investigated, if the use of the in Germany new active ingredient imazamox enlarge the possibilities of post emergence weed control in soybeans. Furthermore new herbicide strategies were tested on efficacy and selectivity in soybeans. The use of imazamox was very selective and showed a relative broad spectrum of controlled weed species. However, efficacy of imazamox must be supported by a pre-emergence treatment and in most cases by a tank mix partner. For example cleavers (Galium aparine can not be controlled by imazamox. Tankmixtures of imazamox and bentazon indicated an antagonism. Efficacy to some weed species was reduced compared to solo application. The low dose concept – three applications of low doses at cotyledon stage of weeds led to some success. However, these strategies must be further investigated, before they can be recommended to commercial farming practice. All herbicide strategies tested showed some surviving weed species. This indicates that choice of herbicides, dose rates and application strategies must be done very careful and site specific.

  9. Chemical Weed Control in Saffron (Crocus sativus Fields

    Directory of Open Access Journals (Sweden)

    majid abbaspoor

    2018-01-01

    Full Text Available Introduction Saffron is derived from the stigmas of the saffron (Crocus sativus L. It is the world’s most expensive spice and has been widely used in many countries. It is also increasingly used for medicinal purposes. Weed control in this perennial, small and low growing crop, needs a lot of labor work. Chemical approach is one of the most effective methods for weed control in saffron. Currently, some herbicide options are available for applications in saffron. For example, satisfactory broadleaved weed control would be achieved by post-emergence application of metribuzin and ioxynil after harvesting saffron flowers. Application of glyphosate and/or 2, 4-D / 2, 4-DB are used to clean up the beds prior to the new season’s flowering and growth of saffron in New Zealand. The selective weed control of weeds in saffron has not been widely reported elsewhere but some in Iran. The choice of herbicide(s depends on the kind of weeds present. In some literatures metribuzin showed promising results for weed control in saffron fields. It is selectively used for control of annual grasses and numerous broad-leaved weeds. The objective of this study was the evaluation of the efficacy of 15 herbicides with different mode of actions, selected on the basis of dominant weed flora and previous studies, on weeds grown in saffron fields. Materials and Methods A field study was conducted to evaluate the efficacy of herbicides for weed control in saffron (Crocus sativus in Agricultural and Natural Resources Research and Education Center of Khorasan Razavi Province, Mashhad, in 2014-2015 growing season. The experiment was conducted in a completely randomized block design with three replications. Treatments were consisted of metsulfuron-methyl + sulfosulfuron (Total® at dose of 40 g ha-1, sulfosulfuron (Apirus® at dose of 26.6 g ha-1, oxadiazon (Ronestar® at dose of 2 l ha-1, oxyflurofen (Goal® at dose of 2 l ha-1, mesosulfuron + idosulfuron + diflufenican

  10. Microwave Technologies as Part of an Integrated Weed Management Strategy: A Review

    Directory of Open Access Journals (Sweden)

    Graham Brodie

    2012-01-01

    Full Text Available Interest in controlling weed plants using radio frequency or microwave energy has been growing in recent years because of the growing concerns about herbicide resistance and chemical residues in the environment. This paper reviews the prospects of using microwave energy to manage weeds. Microwave energy effectively kills weed plants and their seeds; however, most studies have focused on applying the microwave energy over a sizable area, which requires about ten times the energy that is embodied in conventional chemical treatments to achieve effective weed control. A closer analysis of the microwave heating phenomenon suggests that thermal runaway can reduce microwave weed treatment time by at least one order of magnitude. If thermal runaway can be induced in weed plants, the energy costs associated with microwave weed management would be comparable with chemical weed control.

  11. Controle de dez espécies daninhas em cana-de-açúcar com o herbicida mesotrione em mistura com ametryn e metribuzin Control of ten weed species in sugarcane using mesotrione mixed with ametryn and metribuzin

    Directory of Open Access Journals (Sweden)

    F.T. Carvalho

    2010-01-01

    -emergence control is the great challenge. The objective of this work was to evaluate the efficiency of the herbicide mesotrione in mixture with ametryn and metribuzin in the post-emergence control of ten weeds sown in sugarcane, variety RB86-7515. The weeds used in the experiment were: Brachiaria decumbens, Brachiaria plantaginea, Cenchrus echinatus, Digitaria horizontalis, Panicum maximum, Amaranthus deflexus, Bidens pilosa, Euphorbia heterophylla, Ipomoea nil and Sida glaziovii, sown in between the rows after crop emergence. The herbicides were applied on the 45th day after sugarcane planting when the monocotyledon weeds reached the third tiller phase and the dicotyledon weeds completed three to four leaves. The following treatments were carried out: mesotrione (120 g ha-1; ametryn (2,000 g ha-1; metribuzin (1,920 g ha-1; mesotrione + ametryn (120 g + 2,000 g ha-1; mesotrione + metribuzin (120 g + 1,920 g ha-1 and control with and without weeds. It was concluded that the herbicides, isolated or in mixture, were selective to sugarcane. Regarding control efficiency, it was observed that the herbicide mesotrione was efficient in the control of A. deflexus; ametryn was efficient in the control of A. deflexus, B. pilosa and I. nil; metribuzin was efficient in the control of A. deflexus, B. pilosa and S. glaziovii; mesotrione + ametryn were efficient in the control of B. decumbens, B. plantaginea, D. horizontalis, P. maximum, A. deflexus, B. pilosa, I. nil and S. glaziovii, and mesotrione + metribuzin was efficient in the control of B. plantaginea, D. horizontalis, P. maximum, A. deflexus, B. pilosa and S. glaziovii. A high synergistic effect of mesotrione was verified with the tested herbicides, with the mixture with ametryn being the most prominent.

  12. Uptake of heavy metals by Brachiaria Decumbens and its mutant as a remediation agent for soil contaminated with oil sludge

    International Nuclear Information System (INIS)

    Ahmad Nazrul Abd Wahid; Latiffah Noordin; Abdul Razak Ruslan; Hazlina Abdullah; Khairuddin Abdul Rahim

    2006-01-01

    The Malaysian petroleum industry produces thousands of tonnes of oil sludge per year. Oil sludge is the residue accumulated during processing of petroleum at petroleum processing plants. Besides soil, mud and sand, oil sludge is often rich in radioactive substances, heavy metals and other toxic materials from hydrocarbon group which could contaminate and environment. In the present study the pasture grass Brachiaria decumbens and its mutant B. decumbens Kluang Comel were evaluated on their effectiveness as remediation agents for contaminated soils. The contaminating agent tested was the oil sludge with its hydrocarbons vaporised, obtained from the Waste Management Centre, MINT. Amongst the indicators for an effective remediation agent is the ability to accumulate heavy metals in their tissues without affecting their growth. This trial was conducted at MINT glasshouse, whereby the test plants were planted in pots in soil added with vaporised oil sludge. Analysis of heavy metals was through Inductive Coupled Plasma Mass Spectrometry (ICPMS) and Neutron Activation Analysis (NAA). This paper discusses the accumulation of heavy metals by B. decumbens and its mutant Kluang Comel and their growth performance, hence assessing their suitability as remediation agent in soil contaminated with oil sludge. (Author)

  13. Beef production in irrigated and fertilized pastures of Brachiaria hybrid cv. Mulato II at the Sinú valley

    Directory of Open Access Journals (Sweden)

    Sony Reza

    2015-01-01

    Full Text Available The main objective of this study was to evaluate the production of meat during the dry period in Brachiaria hybrid cv. Mulato II pasture with three stocking rates, irrigated and spring fertilized. The research was conducted for 140 days at the Center for Research Turipaná of the Colombian Corporation of Agricultural Research (Corpoica, located at Cereté, Córdoba (Colombia. Were grazed 48 cattle, commercial zebu with average weight of 339 ± 29 kg in an area of 12 hectares. Three treatments (3, 4, 5 animals/ha were evaluated with two replications in a randomized block design. Production, chemical and botanical composition, in situ degradability of dry matter and the daily weight gain was determined. Economic feasibility was determined by the benefit/cost ratio. The dry matter production was 1.925.16, 1.111.18 and 884.92 kg ha-1 for treatments 3, 4, 5 animal/ha respectively, detected differences (p0.05. For daily gain analysis found differences (p<0.05, with gains of 1.07, 0.989 and 0.940 kg animal for treatments 3, 4, 5 animal/ha. The treatment 5 animal/ha provided the best indicators economical.

  14. Spatial variability of forage yield and soil physical attributes of a Brachiaria decumbens pasture in the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    Cristiano Magalhães Pariz

    2011-10-01

    Full Text Available The objective of this study was to analyze variability, linear and spatial correlations of forage dry mass yield (FDM and dry matter percentage (DM% of Brachiaria decumbens with the bulk density (BD, gravimetric (GM and volumetric (VM moisture, mechanical resistance to penetration (RP and organic matter content (OM, at depths 1 (0-0.10 m and 2 (0.10-0.20 m, in a Red Latosol (Oxisol, in order to select an indicator of soil physical quality and identify possible causes of pasture degradation. The geostatistical grid was installed to collect soil and plant data, with 121 sampling points, over an area of 2.56 ha. The linear correlation between FDM × DM% and FDM × BD2 was low, but highly significant. Spatial correlations varied inversely and positively, respectively. Except for DM% and BD, at both depths, the other attributes showed average to high variability, indicating a heterogeneous environment. Thus, geostatistics emerges as an important tool in understanding the interactions in pasture ecosystems, in order to minimize possible causes of degradation and indicate better alternatives for soil-plant-animal management. The decrease in FDM and increased BD1 are indicators of physical degradation (compaction of Red Latosol (Oxisol, particularly in the places with the highest concentration of animals and excessive trampling, in Cerrado conditions, in the municipality of Selvíria, Mato Grosso do Sul State, Brazil.

  15. Priming and stress under high humidity and temperature on the physiological quality of Brachiaria brizantha cv. MG-5 seeds

    Directory of Open Access Journals (Sweden)

    Thiago Barbosa Batista

    2016-01-01

    Full Text Available Palisade grass is a forage plant that is widely used in pasture cropping in the Brazilian savannah. The aim of this experiment was to evaluate palisade grass (Brachiaria brizantha cv. MG–5 seeds subjected to priming and stress at high humidity and temperature (before and after conditioning. The experimental design was completely randomized in a 2x5 factorial arrangement. Seeds were exposed to stress under high humidity and temperature (before and after conditioning and five priming treatments [Water (Control, potassium nitrate (KNO3 at 0.2%, calcium nitrate Ca(NO32 at 0.2%, gibberellin (GA3 at 0.2% and glucose at 10%] with four replications. Two experiments were performed: Experiment I - seed with chemical scarification using H2SO4 and Experiment II - without scarification. The stress on the seed was applied using artificial aging at 41°C for 96 hours. Seed priming was accomplished by immersion at 25°C for 2 hours. Thereafter, the seeds were oven-dried at 35°C until they regained hygroscopic equilibrium. Seed germination and vigor were evaluated. Priming using KNO3 and Ca(NO32 produced seeds with high tolerance to stress under high temperature, and this process is efficient to overcome dormancy.

  16. High degree of genetic diversity among genotypes of the forage grass Brachiaria ruziziensis (Poaceae) detected with ISSR markers.

    Science.gov (United States)

    Azevedo, A L S; Costa, P P; Machado, M A; de Paula, C M P; Sobrinho, F S

    2011-11-17

    The grasses of the genus Brachiaria account for 80% of the cultivated pastures in Brazil. Despite its importance for livestock production, little information is available for breeding purposes. Embrapa has a population of B. ruziziensis from different regions of Brazil, representing most of existing variability. This population was used to initiate an improvement program based on recurrent selection. In order to assist the genetic improvement program, we estimated the molecular variability among 93 genotypes of Embrapa's collection using ISSR (inter-simple sequence repeat) markers. DNA was extracted from the leaves. Twelve ISSR primers generated 89 polymorphic bands in the 93 genotypes. The number of bands identified by each primer ranged from two to 13, with a mean of 7.41. Cluster analysis revealed a clearly distinct group, containing most of the B. ruziziensis genotypes apart from the outgroup genotypes. Genetic similarity coefficients ranged from 0.0 to 0.95, with a mean of 0.50 and analysis of molecular variance indicated higher variation within (73.43%) than among species (26.57%). We conclude that there is a high genetic diversity among these B. ruziziensis genotypes, which could be explored by breeding programs.

  17. Ingestive behavior of cattle kept in Brachiaria brizantha cv. Xaraés grass managed under different grazing heights

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Alves de Freitas Barbosa

    2014-02-01

    Full Text Available This experiment was conducted to evaluate the effect of grazing heights on daytime behavioral activities of Nellore beef cattle in the rainy season. The experimental area was 12 hectares divided into paddocks of one hectare each. The treatments consisted of four defoliation heights (15, 30, 45 and 60 cm in pastures of Brachiaria brizantha cv. Xaraés with three replicates each. It was used the continuos grazing method, with variable stocking rate. Forage samples collected on the plots were sent to the laboratory for separation of the botanical components, weighing and determination of dry matter, with the material collected by simulated grazing. The variables: grazing time, idle time and ruminating time were evaluated for 12 consecutive hours on days 15 and 16 February 2011, considering the morning and afternoon periods. It was used a completely randomized design. The height of the canopy significantly influenced the daily grazing time and ruminating time, with a quadratic response as a function of time of defoliation. The bite rate decreased as a function of heights studied. However the chemical composition of the material collected by simulated grazing did not differ between treatments. Xaraés grass swards grazed at around 45 cm height provide greater ease of apprehension by grazing cattle.

  18. Distribution Map and Community Characteristics of Weeds in Barley Fields of Ardabil Province

    OpenAIRE

    B. Soheili; M. Minbashi; D. Hasanpanah; N. Razmi

    2013-01-01

    Surveying weeds of irrigated barley fields is one of the most important practices in weed management. Based on cultivated areas irrigated barley in all counties of Ardabil province during six years (2000-2005), 46 sample barley fields were selected and weed species were counted in each sampling point and population indices were calculated with Thomas method. By using specific furmula the density, frequency and uniformity of each weed species in fields were calculated. In each field longitude,...

  19. Evaluation of mulching materials as integrated weed management component in maize crop

    International Nuclear Information System (INIS)

    Shah, F.U.

    2014-01-01

    Yield losses by weeds in maize crop and demonstrated efficacy of various mulches in weed management led to check the efficacy of various available mulches for suppressing weeds in maize crop at National Agricultural Research Centre (NARC), Islamabad during kharif (autumn) season 2011. The experiment was laid in Randomized Complete Block Design, (RBCD) having eight treatments and four replications. The treatments were black plastic, white plastic, sugarcane straw, wheat straw, live mulch, weeds as mulch, hand weeding and weedy check. Weed data included weed density m, fresh and dry weight g m, while crop data included crop density m, fresh and dry weight g m, number of plant plot, stover yield (g), plant height (cm), number of cobs plant, number of leaves plant, average grain number of five cobs and grain yield (t ha). With the exception of hand weeding, minimum number of weeds 128 m and 164 m were recorded in black plastic and weeds as mulch, respectively, compared to 595 min weedy check. Similarly, maximum grain yields (1.91 and 1.85 tha) were recorded in black plastic and weeds as mulch, while minimum grain yield (0.64 t ha) was recorded in weedy check plots. The economic net returns of black plastic mulch and weeds as mulch were Rs. 39,824 and Rs. 38,291, respectively as compared to Rs. 21431 for weedy check. Yield increased by 21.1 and 16.5% over hand weeding by plastic mulch and weeds as mulch, respectively. Black plastic followed by weeds as mulch, are recommended to control weeds and get maximum yield as well as net economic return. (author)

  20. Host Status of Seven Weed Species and Their Effects on Ditylenchus destructor Infestation of Peanut

    OpenAIRE

    De Waele, D.; Jordaan, Elizabeth M.; Basson, Selmaré

    1990-01-01

    The host suitability to Ditylenchus destructor of seven common weed species in peanut (Arachis hypogaea) fields in South Africa was determined. Based on the number of nematodes per root unit, white goosefoot (Chenopodium album), feathertop chloris (Chloris virgata), purple nutsedge (Cyperus rotundus), jimson weed (Datura stramonium), goose grass (Eleusine indica), khaki weed (Tagetes minuta), and cocklebur (Xanthium strumarium) were poor hosts. Ditylenchus destructor survived on all weed spec...

  1. Germinação de sementes de Sida rhombifolia e Brachiaria decumbens influenciada por vinhaça, flegmaça e óleo de fúsel Germination of Sida rhombifolia and Brachiaria decumbens seeds influenced by vinasse, flegmass and fusel oil

    Directory of Open Access Journals (Sweden)

    A.A.P.M. Azania

    2003-12-01

    Full Text Available Este trabalho objetivou avaliar, em condições de laboratório, a germinação de sementes de Sida rhombifolia e Brachiaria decumbens submetidas à aplicação de vinhaça, flegmaça e óleo de fúsel. Esses subprodutos, nas concentrações de 12,5; 25,0; 50,0; e 100,0% (v/v, e as testemunhas (água com pH e osmolalidade corrigidos, em função da caracterização realizada nos subprodutos e em suas diluições foram aplicados diretamente em 100 sementes acondicionadas em caixas de plástico, utilizando papel como substrato. O delineamento experimental foi o inteiramente casualizado, e as médias obtidas foram submetidas ao teste de Tukey. As sementes de Sida rhombifolia submetidas ao óleo de fúsel não germinaram e apresentaram redução na viabilidade, principalmente nas maiores concentrações de aplicação. As sementes de Brachiaria decumbens submetidas à maior concentração de flegmaça apresentaram tendência de redução da viabilidade e do índice de velocidade de germinação (IVG. Na presença do óleo de fúsel as sementes de Brachiaria decumbens não germinaram e apresentaram-se totalmente inviáveis.This research aimed to evaluate the effects of vinasse, flegmass and fusel oil (distillery by-products on the germination of Sida rhombifolia and Brachiaria decumbens seeds, under laboratory conditions. By-product concentrations (12.5; 25.0; 50.0 and 100.0% v/v and the controls (water with pH and osmolality amended according to by-product composition and levels were applied directly on plastic boxes filled with 100 seeds of the same species. The experiment was arranged in a randomized complete design and the data were submitted to the Tukey test. Sida rhombifolia seeds submitted to fusel oil did not germinate, reducing seed viability mainly at the largest application rates. Brachiaria decumbens seeds submitted to the highest flegmass rate tended to reduce seed viability and germination speed index (GSI. Brachiaria decumbens seeds

  2. Spatial correlation between weed species densities and soil properties

    DEFF Research Database (Denmark)

    Walter, Mette; Christensen, Svend; Simmelsgaard, Svend Erik

    2002-01-01

    The spatial cross-correlation between weed species densities and six soil properties within fields was analysed using cross-semivariograms. The survey was carried out in three successive years in two fields. The most consistent relationship between weed species density (numbers m−2) and soil...... properties was negative cross-correlation between the density of Viola arvensis Murray and clay content. This correlation was found in both fields; however, the range of spatial dependence varied between fields. In one of the fields, the density of Lamium purpureum L. was positively cross......-correlated with the phosphorus content in the soil in all years. The density of Veronica spp. and Poa annua L. was negatively cross-correlated with pH in all three years. Other spatial cross-correlations that were found in this study were inconsistent over time or field site. The densities of some of the weed species were...

  3. Weed control through crop rotation and alternative management practices

    Directory of Open Access Journals (Sweden)

    Böhm, Herwart

    2014-02-01

    Full Text Available Economic as well as agricultural and socio-political changes have an impact on crop management and thus also on crop rotation design and the related effects on the weed flora. Likewise other changes in cultivation such as reduced tillage practices, earlier sowing date, etc. cause an increase in weed infestation resp. an increased use of herbicides and if so contribute to herbicide resistance. The positive effects of crop rotation, but also of alternative management practices such as choice of varieties, catch crops, mixed cropping, green chop, and the share of predators, as well as methods of direct non-chemical weed control are presented and discussed for both, conventional and organic farming. If alternative management methods should be more practiced, especially trade-offs need to be broken, or incentives be offered.

  4. Development of an Autonomous Vehicle for Weed and Crop Registration

    DEFF Research Database (Denmark)

    Pedersen, Tom Søndergaard; Nielsen, Kirsten Mølgaard; Andersen, Palle

    The extension of information technology and computers on farming tools results in new possibilities for crop/weed handling. In this paper a system using an autonomous field robot (vehicle) able to make images in the field is described. In the recent farming has come to rely on intensive use...... degree of autonomy. The vehicle is part of an autonomous information system for crop and weed registration in fields which is developed at Aalborg University and The Danish Institute of Agricultural Science. The system consists of the vehicle and a stationary base station as well as a wireless...... be a solution but at present the image analysis technology does not have the capability for online analysis. An alternative way is to construct a weed map prior to the spraying. In order to avoid damage to the soil a light weight vehicle carrying a camera is an obvious choice. To minimize damage to the crop...

  5. Smoking the Other: marijuana and counterhegemony in Weeds.

    Science.gov (United States)

    Lavoie, Dusty

    2011-01-01

    Subverting suburban modernity, the SHOWTIME television series Weeds invites its audiences to situate their opinions about marijuana amid spheres of bourgeois soccer-moms, class politics, turf wars, raw economics, violent milieux, and multiculti heterogeneity. I argue that Weeds encourages us to "smoke the Other"; that is, to hesitantly accept difference, in line with many drug circles' etiquette. The phrase "smoking the Other" is a critical alteration of bell hooks' (1992, Black looks: Race and representation. Boston: South End Press) conception of whites' ethnic "devouring" as "eating the Other," a rather rigid schematic itself problematized by Weeds' transgressive self-conscious playfulness with stereotyped ethnicities, loopy plotlines, and counterhegemonic dialogue. Cultural/political implications follow. Copyright © 2011 Informa Healthcare USA, Inc.

  6. Weed management: a case study from north-west Pakistan

    International Nuclear Information System (INIS)

    Marwat, K.B.; Hashim, S.; Ali, H.

    2010-01-01

    Alien and exotic plant invasions are threatening the floral diversity around the globe and affect ecological processes. Weed invasion has been documented in North-West Pakistan. A total of 16 weeds were reported as invasive. These were Xanthium strumarium, Ipomoea eriocarpa, Alternanthera pungens, Trianthema portulacastrum, Tagetes minuta, Imperata cylindrica, Amaranthus hybridus subsp. hybridus, Robinia pseudo-acacia, Broussonetia papyrifera, Ailanthus altissima, Pistia stratiotes, Phragmites australis, Parthenium hysterophorus, Cannabis sativa, Galium aparine and Emex spinosus. Among these Robinia pseudo-acacia, Broussonetia papyrifera and Ailanthus altissima are trees and were purposely introduced as they later became invasive. They were aggressive in nature and replaced or suppressed the local vegetation. Their distribution, history of invasion and management has been discussed here. The behaviour and association of the 36 problem weeds with different crops has also been outlined as they perspired from the farmers. (author)

  7. Weed management: a case study from north-west Pakistan

    Energy Technology Data Exchange (ETDEWEB)

    Marwat, K B; Hashim, S; Ali, H [KPK Agriculture University, Peshawar (Pakistan). Dept. of Weed Science

    2010-12-15

    Alien and exotic plant invasions are threatening the floral diversity around the globe and affect ecological processes. Weed invasion has been documented in North-West Pakistan. A total of 16 weeds were reported as invasive. These were Xanthium strumarium, Ipomoea eriocarpa, Alternanthera pungens, Trianthema portulacastrum, Tagetes minuta, Imperata cylindrica, Amaranthus hybridus subsp. hybridus, Robinia pseudo-acacia, Broussonetia papyrifera, Ailanthus altissima, Pistia stratiotes, Phragmites australis, Parthenium hysterophorus, Cannabis sativa, Galium aparine and Emex spinosus. Among these Robinia pseudo-acacia, Broussonetia papyrifera and Ailanthus altissima are trees and were purposely introduced as they later became invasive. They were aggressive in nature and replaced or suppressed the local vegetation. Their distribution, history of invasion and management has been discussed here. The behaviour and association of the 36 problem weeds with different crops has also been outlined as they perspired from the farmers. (author)

  8. Weed seed predation in organic and conventional fields

    DEFF Research Database (Denmark)

    Navntoft, Søren; Wratten, S.D.; Kristensen, Kristian

    2009-01-01

    Enhanced biological control of weed seeds may improve sustainability of agricultural production. Biological control due to seed predation may be higher in organic fields because organic production generally supports more seed predators. To investigate such a difference, weed seed predation...... University and in two of the fields used for estimating seed predation. Recording of predators had therefore limited overlap with seed predation assays but was expected to give important information on key seed predators in the region. The mean seed removal rate was 17% in organic fields compared with 10...... edges. Overall, there was no consistent effect of distance from the field edge. Vegetation had a significant influence on the predation rates, with maximum rates at a medium-dense plant cover. Based on the video images, birds were the most important seed predators. The higher weed seed predation rate...

  9. Alternative surfacing materials for weed control at BC Hydro substations

    International Nuclear Information System (INIS)

    Wells, T.C.; Shrimpton, G.M.

    1997-01-01

    A two year study was conducted by BC Hydro in which a variety of surfacing materials were tested for their suitability for use in substations. Ideally, surfacing materials should have the following characteristics: high electrical resistivity in both dry and wet conditions, resistance to invasion by weeds, good driveability, good drainage, non-flammable, reasonably priced, no dust to foul conductors, and be aesthetically pleasing. Trials at Vernon Koksilah, and Ingledow substations were conducted to test the materials. A qualitative estimate of the amount of weed control provided by each material was recorded. The trials were meant to provide operational recommendations and screening information to allow for future testing of promising materials or combination of materials. Results showed that no single material meets all the desired criteria. The surfaces that best combined good weed control, electrical resistance and surface stability was a 15 cm deep layer of crushed gravel, especially if underlain by a layer of geotextile. 4 refs., 3 tabs., 1 fig

  10. Organic Highbush Blueberry Production Systems Research – Management of Plant Nutrition, Irrigation Requirements, and Weeds

    Science.gov (United States)

    A 0.4 ha planting of blueberry was established in October 2006 to evaluate the effects of cultivar (Duke and Liberty), bed type (flat versus raised beds), weed management (sawdust mulch and hand-weed control; sawdust+compost mulch with acetic acid, flaming, and hand control used as needed; and weed ...

  11. Economics of weed suppressive rice cultivars in flood- and furrow-irrigated systems

    Science.gov (United States)

    Weeds are a major constraint to rice production. In the U.S, weeds in rice are controlled primarily with synthetic herbicides. Intensive herbicide application in rice also has many potential drawbacks, resulting in environmental pollution, human health concerns, and development of weed resistance. B...

  12. Effect of weed control methods on some soil properties of a newly ...

    African Journals Online (AJOL)

    Weed control constitutes a high percentage of the total field maintenance cost of newly planted cocoa. Soil samples were collected from an experiment that was designed to evaluate some weed control methods during cocoa establishment. The objective of the experiment was to assess the effect of the weed control ...

  13. Yield loss prediction models based on early estimation of weed pressure

    DEFF Research Database (Denmark)

    Asif, Ali; Streibig, Jens Carl; Andreasen, Christian

    2013-01-01

    thresholds are more relevant for site-specific weed management, because weeds are unevenly distributed in fields. Precision of prediction of yield loss is influenced by various factors such as locations, yield potential at the site, variation in competitive ability of mix stands of weed species and emergence...

  14. Narrow rows reduce biomass and seed production of weeds and increase maize yield

    NARCIS (Netherlands)

    Mashingaidze, A.B.; Werf, van der W.; Lotz, L.A.P.; Chipomho, J.; Kropff, M.J.

    2009-01-01

    Smallholder farmers in southern African countries rely primarily on cultural control and hoe weeding to combat weeds, but often times, they are unable to keep up with the weeding requirements of the crop because of its laboriousness, causing them to incur major yield losses. Optimisation of crop

  15. The effect of environmental conditions on the seasonal dormancy pattern and germination of weed seeds

    NARCIS (Netherlands)

    Bouwmeester, H.J.

    1990-01-01

    Weeds cause considerable losses in horticultural and agricultural crops. Weeds are still predominantly controlled with herbicides. To reduce the use of chemicals, a better understanding of the biology of weeds is required. In this thesis the effect of environmental conditions on dormancy

  16. On the development, environmental effects and human dimension of weed management strategies

    NARCIS (Netherlands)

    Riemens, M.M.

    2009-01-01

    On the development, environmental effects and human dimension of weed management strategies. On farm weed management is influenced by many factors. These factors comprise the development and availability of weed management tools, the environmental impact of these tools and the attitude and

  17. Trade off between costs and environmental effects of weed control on pavements

    NARCIS (Netherlands)

    Kempenaar, C.; Lotz, L.A.P.; Horst, van der C.L.M.; Beltman, W.H.J.; Leemans, K.J.M.; Bannink, A.D.

    2007-01-01

    An actor-participative project on sustainable weed control on pavements was started in 2000 in the Netherlands. The aim of the project was to develop a new concept of weed management that provides cost-effective and environmentally sound weed control. Early in 2002, practical guidelines were drawn

  18. 7 CFR 205.206 - Crop pest, weed, and disease management practice standard.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Crop pest, weed, and disease management practice... Requirements § 205.206 Crop pest, weed, and disease management practice standard. (a) The producer must use management practices to prevent crop pests, weeds, and diseases including but not limited to: (1) Crop...

  19. Using a fully convolutional neural network for detecting locations of weeds in images from cereal fields

    DEFF Research Database (Denmark)

    Dyrmann, Mads; Skovsen, Søren; Sørensen, René A.

    2018-01-01

    been evaluated on an Nvidia Titan X, on which it is able to process a 5MPx image in 0.02s, making the method suitable for real-time field operation. For mechanical weed control, this network is sufficient. However, for chemical weed control, we also need to know the weed species in order to choose...

  20. Influence of maize herbicides on weed seed bank diversity in a ...

    African Journals Online (AJOL)

    Influence of maize herbicides on weed seed bank diversity in a humid forest ... at 2.0 +2.0kg ai ha-1 was more effective in reducing weed seeds (seed bank) than the ... pre-emergence weed control program in diverse arable cropping systems ...

  1. Weed control using ammonium nonanoate and cultivation in organic Vidalia sweet onion production

    Science.gov (United States)

    Ammonium nonanoate is registered for weed control in certified organic crop production and may be useful to control cool-season weeds in organic Vidalia® sweet onion. Cultivation with a tine weeder has been identified as a cost-effective means of weed control, but delays in cultivation cause some w...

  2. The Art and the Science of Cultivation for Weed Control in Organic Peanut

    Science.gov (United States)

    Cultural weed control is the basis on which an integrated system of weed management in organic peanut is based. The cultural practices evaluated for weed control were row patterns and seeding rates, integrated with cultivation intensity. Results showed that peanut seeded in wide rows (two rows, 91...

  3. Determination of critical period for weed control in the second crop ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-09-15

    Sep 15, 2009 ... maximize crop yield by eliminating weed competition and/ or minimizing ... fertilizer. When corn plants reached 80 cm in height, 170 kg N ha-1 was applied ... describing the effect of increasing duration of weed interference on corn yield ... corresponding value of length of weed-free period (d°C) and b and.

  4. Predicting field weed emergence with empirical models and soft computing techniques

    Science.gov (United States)

    Seedling emergence is the most important phenological process that influences the success of weed species; therefore, predicting weed emergence timing plays a critical role in scheduling weed management measures. Important efforts have been made in the attempt to develop models to predict seedling e...

  5. The Power and Potential of Genomics in Weed Biology and Management.

    Science.gov (United States)

    Ravet, Karl; Patterson, Eric L; Krähmer, Hansjörg; Hamouzová, Kateřina; Fan, Longjiang; Jasieniuk, Marie; Lawton-Rauh, Amy; Malone, Jenna M; Scott McElroy, J; Merotto, Aldo; Westra, Philip; Preston, Christopher; Vila-Aiub, Martin M; Busi, Roberto; Tranel, Patrick J; Reinhardt, Carl; Saski, Christopher; Beffa, Roland; Neve, Paul; Gaines, Todd A

    2018-04-24

    There have been previous calls for, and efforts focused on, realizing the power and potential of weed genomics for better understanding of weeds. Sustained advances in genome sequencing and assembly technologies now make it possible for individual research groups to generate reference genomes for multiple weed species at reasonable costs. Here, we present the outcomes from several meetings, discussions, and workshops focused on establishing an International Weed Genomics Consortium (IWGC) for a coordinated international effort in weed genomics. We review the 'state of the art' in genomics and weed genomics, including technologies, applications, and on-going weed genome projects. We also report the outcomes from a workshop and a global survey of the weed science community to identify priority species, key biological questions, and weed management applications that can be addressed through greater availability of, and access to, genomic resources. Major focus areas include the evolution of herbicide resistance and weedy traits, the development of molecular diagnostics, and the identification of novel targets and approaches for weed management. There is increasing interest in, and need for, weed genomics, and the establishment of the IWGC will provide the necessary global platform for communication and coordination of weed genomics research. This article is protected by copyright. All rights reserved.

  6. Lawn Weed Control with Herbicides. Home and Garden Bulletin No. 123.

    Science.gov (United States)

    Agricultural Research Service (USDA), Washington, DC.

    Information and diagrams are given for identification and treatment of weed grasses and broadleaf weeds. Herbicides are suggested for use against each weed and instructions are given for proper application. Information is given for buying herbicides, and applying sprays and cleaning sprayers. (BB)

  7. Control of perennial weeds by mechanical methods and anaerobic soil disinfection

    NARCIS (Netherlands)

    Huiting, H.F.; Bleeker, P.O.; Riemens, M.M.

    2011-01-01

    Perennial weeds are difficult to control and ask for a specific approach. During the most recent years it has even become a great challenge to control these weeds in conventional farming systems, although in comparison effective perennial weed control in organic farming systems remains more

  8. Fuels planning: science synthesis and integration; environmental consequences fact sheet 07: fire and weeds

    Science.gov (United States)

    Steve Sutherland

    2004-01-01

    Weed infestations cause an economic loss of $13 billion per year even though $9.5 billion per year is spent on weed control measures. In addition to these economic costs, weeds are replacing native species, altering native plant and animal communities, affecting ecosystem health and function, threatening biodiversity and Threatened, Endangered, and Sensitive (TES)...

  9. Phenological observations on shrubs to predict weed emergence in turf

    Science.gov (United States)

    Masin, Roberta; Zuin, Maria Clara; Zanin, Giuseppe

    2005-09-01

    Phenology is the study of periodic biological events. If we can find easily recognizable events in common plants that precede or coincide with weed emergences, these plants could be used as indicators. Weed seedlings are usually difficult to detect in turf, so the use of phenological indicators may provide an alternative approach to predict the time when a weed appears and consequently guide management decisions. A study was undertaken to determine whether the phenological phases of some plants could serve as reliable indicators of time of weed emergence in turf. The phenology of six shrubs (Crataegus monogyna Jacq., Forsythia viridissima Lindl., Sambucus nigra L., Syringa vulgaris L., Rosa multiflora Thunb., Ziziphus jujuba Miller) and a perennial herbaceous plant [Cynodon dactylon (L.) Pers.] was observed and the emergence dynamics of four annual weed species [Digitaria sanguinalis (L.) Scop., Eleusine indica (L.) Gaertner, Setaria glauca (L.) Beauv., Setaria viridis (L.) Beauv.] were studied from 1999 to 2004 in northern Italy. A correlation between certain events and weed emergence was verified. S. vulgaris and F. viridissima appear to be the best indicators: there is a quite close correspondence between the appearance of D. sanguinalis and lilac flowering and between the beginning of emergence of E. indica and the end of lilac flowering; emergences of S. glauca and S. viridis were predicted well in relation to the end of forsythia flowering. Base temperatures and starting dates required to calculate the heat unit sums to reach and complete the flowering phase of the indicators were calculated using two different methods and the resultant cumulative growing degree days were compared.

  10. Weed diversity identification on growth phases of twelve maize varieties

    Science.gov (United States)

    Rahayu, M.; Yudono, P.; Indradewa, D.; Hanudin, E.

    2018-03-01

    Weed is one of the factors that disturb maize cultivation. Each maize variety has specific characteristics which will lead to weeds diversity in particular farm. This study aimed to identify the effect of maize variety on weed diversity on maize’s growth phases. The research was conducted from March to July 2016 in Banguntapan, Bantul, Yogyakarta, Indonesia. The field research was arranged by using Randomised Complete Block Design with three replications. The treatments were maize varieties, consist of 12 levels: ‘Bisi 18’, ‘Bisi 2’, ‘Pertiwi 3’, ‘NK 22’, ‘NK 33’, ‘DK 959’, ‘P23’, ‘DK 771’, ‘DK 95’, ‘Bima 19 Uri’, ‘Bisma’, and ‘Sukmaraga’. The results showed that at four weeks after planting (WAP) the most of weeds were growing on varieties ‘Bisi 18’, ‘NK 33’, ‘P 23’, and ‘DK 95’, there were 14 species. Bulbostylispuberula and Cyperusrotundus were growing on all maize varieties with the highest SDR on ‘Sukmaraga’ and ‘DK 959’. At six WAP, weeds that grew, most consists of four species of sedges, six species of grasses and 24 species of broadleaf. While at the age of eight WAP, the weeds that grow at least on ‘NK 33’ that were 13 species and the most on ‘P23’ that were 21 species. Dactyloctenium aeghypthium having highest SDR in all maize varieties except Bisi 18. The highest SDR value on Bisi 18 was Boerhaavia erecta about 16.23%.

  11. Weed Growth Stage Estimator Using Deep Convolutional Neural Networks

    DEFF Research Database (Denmark)

    Teimouri, Nima; Dyrmann, Mads; Nielsen, Per Rydahl

    2018-01-01

    conditions with regards to soil types, resolution and light settings. Then, 9649 of these images were used for training the computer, which automatically divided the weeds into nine growth classes. The performance of this proposed convolutional neural network approach was evaluated on a further set of 2516...... in estimating the number of leaves and 96% accuracy when accepting a deviation of two leaves. These results show that this new method of using deep convolutional neural networks has a relatively high ability to estimate early growth stages across a wide variety of weed species....

  12. Weed control, biomass and microbial metabolism of soil depending on the application of glyphosate and imazethapyr on crop soybeansControle de plantas daninhas, biomassa e metabolismo microbiano do solo em função da aplicação de glifosato ou imazetapir na cultura da soja

    Directory of Open Access Journals (Sweden)

    Dirceu Agostinetto

    2011-08-01

    Full Text Available Studied the weed control and the changes of biomass and microbial soil properties at crop cultivated both genetically modified and non altered soybeans because of glyphosate or imazethapyr herbicide applications. Soybean cultivations were tested (BRS 244RR, genetically modified and BRS 154, non modified and herbicides (glyphosate and imazethapyr, and control treatment with weed. Variables were evaluated for phytotoxicity to the crop, control of Raphanus raphanistrum (wild radish, Digitaria sp. (crabgrass and Brachiaria plantaginea (alexsandregrass, total organic carbon (TOC, microbial biomass carbon (MBC, basal respiration (BR and metabolic quocient (QCO2. The herbicide glyphosate, applied as a single dose or sequentially, effectively controls the weeds wild radish, crabgrass and alexsandregrass and increases microbial activity, basal respiration and metabolic quocient. The microbial metabolism was not affected by the fact that the genotype or not genetically modified, but the use of the herbicide glyphosate.Estudou-se o controle de plantas daninhas, as variações da biomassa e do metabolismo microbiano do solo em áreas cultivadas com soja geneticamente modificada e não modificada, em função da aplicação dos herbicidas glifosato ou imazetapir. Testaram-se cultivares de soja (BRS 244RR, geneticamente modificada e BRS 154, não modificada e herbicidas (glifosato e imazetapir, e tratamento controle com capina. Como variáveis foram avaliadas a fitotoxicidade à cultura, controle de Raphanus raphanistrum (nabo, Digitaria sp. (milhã e Brachiaria plantaginea (papuã, teores de carbono orgânico total (COT, carbono da biomassa microbiana (CBM, respiração basal (RB e quociente metabólico (QCO2. O herbicida glifosato, aplicado em dose única ou seqüencial, controla eficientemente as plantas daninhas nabo, milhã e papuã, e aumenta a atividade microbiana, a taxa de respiração basal e o quociente metabólico. O metabolismo microbiano do solo

  13. Avaliação da sensibilidade de diversas espécies de plantas daninhas aquáticas ao carfentrazone-ethyl, em ambiente controlado Assessment of sensitivity of several aquatic weeds to carfentrazone-ethyl under controlled environment

    Directory of Open Access Journals (Sweden)

    L.L. Foloni

    2005-06-01

    Full Text Available Plantas aquáticas, especialmente macrófitas, tornam-se sério problema em hidrelétricas, afetando a múltipla utilização dos corpos d'água, incluindo produção de peixes e atividades de pesca, perdas d'água por evapotranspiração, esportes aquáticos, canoagem, irrigação e produção de energia nas usinas hidrelétricas. Com o objetivo de analisar o potencial de uso do carfentrazone-ethyl no controle das principais plantas daninhas aquáticas no Brasil, foi instalado um experimento em vasos com água. Utilizaram-se os seguintes tratamentos herbicidas (g i.a. ha-1: carfentrazone-ethyl a 15, 30 e 60; glyphosate a 4.536; 2,4-D a 4.690; imazapyr a 1.250; e uma testemunha sem herbicida. Esses tratamentos foram testados nas seguintes espécies: Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes, Myriophyllum aquaticum, Brachiaria arrecta, Hydrocotyle umbellata, Typha sp. e Echinochloa polystachya. As avaliações foram efetuadas aos 7, 14, 21 e 28 dias após os tratamentos. Os resultados mostraram que o carfentrazone-ethyl foi eficiente no controle de E. crassipes (maior dose e P. stratiotes (duas maiores doses, com efeito supressivo sobre S. auriculata. Foi observado que nas outras plantas daninhas estudadas não houve eficiência de controle.Aquatic weeds, especially macrophytes, are a serious problem in hydroelectric plant systems, affecting the multiple use of water, such as fish production and fishing activities, water losses by evapotranspiration, aquatic sports, boating, irrigation and hydroelectric power production. An experiment using boxes filled with water was carried out to analyze the potential use of carfentrazone-ethyl in the control of the main aquatic weeds in Brazil. The following herbicide treatments (g i.a. ha-1 were used: carfentrazone-ethyl at 15, 30 and 60; glyphosate at 4,536; 2,4D at 4,690; imazapyr at 1,250, and no herbicide. These treatments were tested on the species: Eichhornia crassipes, Salvinia

  14. Efeito alelopático de capim-braquiária (Brachiaria decumbens sobre o crescimento inicial de sete espécies de plantas cultivadas Allelopathic effects of Brachiaria decumbens on the initial development of seven crops

    Directory of Open Access Journals (Sweden)

    L.S. Souza

    2006-12-01

    Full Text Available O presente trabalho constou de sete experimentos, que foram conduzidos na Faculdade de Ciências Agronômicas, campus de Botucatu, UNESP, São Paulo, Brasil, com o objetivo de avaliar os efeitos alelopáticos de Brachiaria decumbens, colhida em diferentes épocas, sobre o crescimento inicial de milho, arroz, trigo, soja, feijão, algodão e capim-braquiária (B. decumbens, bem como a dinâmica do nitrogênio no solo. A parte aérea de B. decumbens foi coletada durante as estações seca (outono-inverno e chuvosa (primavera-verão, em área de pastagem localizada no município de Botucatu-SP. A matéria seca triturada de B. decumbens foi incorporada ao solo dos vasos na proporção de 3% p/p. O delineamento experimental foi inteiramente casualizado, com cinco repetições. Contando-se a partir do transplante, o experimento foi conduzido por 21 dias para milho e feijão, 24 dias para soja e trigo, 28 dias para arroz e 30 dias para algodão e capim-braquiária. O crescimento dessas plantas foi reduzido com a adição de capim-braquiária para as duas épocas, sendo o próprio capim-braquiária o mais afetado. Os efeitos inibitórios foram mais intensos para capim-braquiária coletado na estação chuvosa. A incorporação da matéria seca da parte aérea de B. decumbens reduziu, significativamente, os teores de nitrato no solo, em todos os estudos realizados.This work consisted of seven experiments carried out at UNESP Botucatu-SP Brazil to evaluate the allelopathic effects of Brachiaria decumbens collected in different seasons on the initial growth of corn, rice, wheat, soybean, bean, cotton and B. decumbens and to evaluate nitrogen dynamics in the soil. The upper part of B. decumbens was collected during the dry and wet seasons in a pasture area located in the district of Botucatu-SP. The dry matter was ground and incorporated into the soil in 3% w/w. The experimental design was arranged in completely randomized plots with 5 replications

  15. Manejo químico de Eichhornia crassipes e Brachiaria subquadripara com Diquat em condições de reservatório Chemical control of Eichhornia crassipes and Brachiaria subquadripara with Diquat under reservoir conditions

    Directory of Open Access Journals (Sweden)

    D. Martins

    2011-03-01

    Full Text Available Este trabalho teve como objetivo avaliar a eficiência do herbicida diquat no controle de plantas de Eichhornia crassipes e Brachiaria subquadripara em condições de reservatório. As parcelas experimentais apresentavam 650 m² e foram delimitadas e posicionadas por redes de pesca nas margens do reservatório de Salto Grande, Americana-SP. Os tratamentos testados foram: herbicida diquat aplicado na formulação Reward, nas doses de 960 g i.a. ha-1 (duas aplicações de 480 g, com intervalo de 15 dias, 960 g i.a. ha-1 (aplicação única, 1.920 g i.a. ha-1 (duas aplicações de 960 g, com intervalo de 15 dias, além de uma testemunha sem aplicação do herbicida. Para monitoramento das concentrações de diquat, foram coletadas amostras de água antes da aplicação do herbicida e 1, 2, 4, 7, 14 e 28 dias após aplicação (DAA na área experimental e na montante e jusante da barragem. A análise da eficiência do diquat foi realizada através de avaliações visuais de controle no período (1, 2, 4, 7, 14, 21 e 28 DAA do herbicida e aos dois dias após a segunda aplicação. O herbicida diquat mostrou-se eficiente no controle das plantas de E. crassipes, independentemente da dose e do manejo de aplicação, e seu efeito sobre as plantas de B. subquadripara foi temporário.This study aimed to evaluate the efficacy of the herbicide diquat in controlling Eichhornia crassipes and Brachiaria subquadripara plants under reservoir conditions. The experimental plots were 650 m², delimited and positioned on the shores of the Salto Grande Reservoir in Americana-SP, Brazil, using fishing nets. The treatments consisted of herbicide diquat, applied as the REWARD commercial formulation at 960 g a.i. ha-1 (two applications at 480 g, at an interval of 15 days, 960 g a.i. ha-1 (single application, 1.920 g a.i. ha-1 (two applications at 960 g, at an interval of 15 days and a control without herbicide application. The concentrations of diquat in water were

  16. Efeito do fósforo suplementar sobre o desempenho reprodutivo de vacas de corte em pastagem de Brachiaria humidicola Effect of phosphorus supplementation on the reproductive performance of beef cows grazing Brachiaria humidicola

    Directory of Open Access Journals (Sweden)

    LUIZ ROBERTO LOPES S'THIAGO

    2000-02-01

    Full Text Available O objetivo deste experimento foi observar e quantificar o efeito de duas misturas minerais (ad libitum, uma sem (M e outra com fósforo suplementar (MP, sobre o desempenho produtivo e reprodutivo de vacas de cria neloradas em pastejo de Brachiaria humidicola. O trabalho foi realizado na Fazenda Modelo (Embrapa-Centro Nacional de Pesquisa de Gado de Corte, localizada em Terenos, MS, em duas fases, a primeira, em 1988/92, e a segunda, em 1992/94. Na segunda fase, reduziu-se a carga animal durante a seca e os dias de amamentação (de 1,0 para 0,5 vacas/ha e de 210 para 90 dias, respectivamente. Foram realizadas medidas de consumo da mistura mineral (M = 76 e MP = 112 g/cab./dia; teor médio de fósforo na forrageira (época das chuvas = 0,16%, época seca = 0,11%; peso vivo (primeira fase: M = 363±3,3 e MP = 371±3,8 kg; segunda fase: M = 407± 5,7 e MP = 417± 6,5 kg; taxa de natalidade (primeira fase: M = 67±3,3 e MP = 66± 3,5%; segunda fase: M = 74± 6,3 e MP = 80± 5,7% e bezerros desmamados (primeira fase: M = 86± 5,0 e MP = 91± 5,3; segunda fase: M = 55± 6,4 e MP = 67± 5,7. As vacas de cria não responderam ao fósforo suplementar.The objective of this experiment was to observe and quantify the effect of two mineral mixtures, as free-choice feeding, one without (M and other with phosphorus supplement (MP, on the productive and reproductive performance of Nellore beef cows grazing Brachiaria humidicola. This work was conducted at the Fazenda Modelo (Embrapa-Centro Nacional de Pesquisa de Gado de Corte, located in Terenos, MS, Brazil, in two phases, 1st from 1988/92 and 2nd from 1992/94. During the 2nd phase, stocking rate, for the dry period, and suckling days were reduced (from 1.0 to 0.5 cows/ha and 210 to 90 days, respectively. Mineral intake (M = 76 and MP = 112 g/had/day, forage phosphorus level (wet season = 0.16%; dry season = 0.11%, liveweight (1st phase: M = 363± 3.3 and MP = 371± 3.8 kg; 2nd phase: M = 407± 5.7 and MP

  17. Growth and biomass allocation of the C4 grasses Brachiaria brizantha and B. humidicola under shade Crescimento e alocação de biomassa nas gramíneas C4 Brachiaria brizantha e B. humidicola sob sombreamento

    Directory of Open Access Journals (Sweden)

    MOACYR BERNARDINO DIAS-FILHO

    2000-12-01

    Full Text Available The growth and biomass allocation responses of the tropical forage grasses Brachiaria brizantha cv. Marandu and B. humidicola were compared for plants grown outdoors, in pots, in full sunlight and those shaded to 30% of full sunlight over a 30day period. The objective was to evaluate the acclimation capacity of these species to low light. Both species were able to quickly develop phenotypic adjustments in response to low light. Specific leaf area and leaf area ratio were higher for low-light plants during the entire experimental period. Low-light plants allocated significantly less biomass to root and more to leaf tissue than high-light plants. However, the biomass allocation pattern to culms was different for the two species under low light: it increased in B. brizantha, but decreased in B. humidicola, probably as a reflection of the growth habits of these species. Relative growth rate and tillering were higher in high-light plants. Leaf elongation rate was significantly increased on both species under low light; however, the difference between treatments was higher in B. brizantha. These results are discussed in relation to the pasture management implications.O crescimento e a alocação de biomassa das gramíneas forrageiras tropicais Brachiaria brizantha cv. Marandu e B. humidicola foram comparados, em plantas cultivadas em vasos, a pleno sol e a 70% de interceptação da luz solar, durante um período de 30 dias. O objetivo foi avaliar a capacidade de aclimatação dessas espécies ao sombreamento. Ambas as espécies mostraram-se capazes de desenvolver rapidamente ajustes fenotípicos em resposta ao sombreamento. A área foliar específica e a razão de área foliar foram maiores durante todo o período experimental, nas plantas cultivadas à sombra. As plantas sombreadas alocaram significativamente menos biomassa nas raízes e mais nas folhas do que as plantas cultivadas à sombra. No entanto, a alocação de biomassa no colmo foi

  18. Evaluación del establecimiento de una colección de accesiones de Brachiaria brizantha asociadas con Stylosanthes guianensis CIAT-184 Evaluation of the establishment of a collection of Brachiaria brizantha accessions associated to Stylosanthes guianensis CIAT-184

    Directory of Open Access Journals (Sweden)

    Yuseika Olivera

    2012-06-01

    Full Text Available En un suelo ácido (pH ~ 4,9, de baja fertilidad, se estudió una colección de 20 accesiones de Brachiaria brizantha asociadas a Stylosanthes guianensis CIAT-184, con el objetivo de evaluar su comportamiento agronómico durante la etapa de establecimiento. Se utilizaron parcelas de 5 x 4 m, con tres réplicas. Los indicadores medidos y/o estimados fueron: el porcentaje de supervivencia (15, 30 y 45 días, la altura de la planta, la abundancia de hojas, el vigor, las afectaciones provocadas por las plagas y la infestación por enfermedades. Para la interpretación de los resultados se utilizó el análisis de componentes principales. En los primeros 45 días las accesiones CIAT-16317, CIAT-26032, CIAT-16485 y el cv. Mulato alcanzaron los mejores índices de supervivencia (por encima del 90%. Después de los 45 días se detectó una alta variabilidad (90,30% para las dos primeras componentes. Al agrupar las accesiones se identificó la formación de siete grupos, en algunos de los cuales predominaron individuos de porte alto, y en otros, plantas con buen vigor y hojosidad. De manera general, se puede concluir que hubo un comportamiento aceptable de la asociación entre las accesiones de B. brizantha y S. guianensis CIAT-184, ya que todas en mayor o menor medida cumplimentaron la etapa de establecimiento. Se destacaron las accesiones de los grupos IV, V y VII, ya que mostraron resultados positivos (por encima de la media en dos indicadores de los tres estimados. Se recomienda dar continuidad a la evaluación de la fase de explotación de este germoplasma con animales, de manera tal que sea posible, en el futuro mediato, seleccionar las accesiones más sobresalientes durante todo el periodo experimental.On a low-fertility, acid soil (pH ~ 4,9, a collection of 20 Brachiaria brizantha accessions associated to Stylosanthes guianensis CIAT-184 was studied, in order to evaluate its agronomic performance during the establishment stage. For such purpose

  19. Cyathostomin larvae: presence on Brachiaria humidicola grass during the rainy and dry seasons of Brazil Larvas de ciatostomíneos: disponibilidade em gramínea Brachiaria humidicola nas estações chuvosa e seca do Brasil

    Directory of Open Access Journals (Sweden)

    Claudia Navarro dos Santos

    2012-03-01

    Full Text Available The presence of cyathostomin larvae is directly associated to climatic conditions of each region. This study aimed to evaluate the ecology of infective larvae on Brachiaria humidicola during the dry and rainy seasons from October 2007 to September 2008 in a tropical region, Rio de Janeiro state, southeastern Brazil. Stools were collected from the rectum of horses naturally infected with cyathostomins at the beginning of the rainy season (October to March and dry season (April to September. They were divided into four samples of 500 g and deposited on a grass patch of B. humidicola. Seven days later and every 15 days thereafter samples of feces and grass were collected and processed by the Baermann technique. The mean number of larvae recovered from the grass varied according to the season, with greater recovery of larvae during the peak of the dry season (14,700 L3.kg-¹ DM. There was a statistically significant difference between L3 recovered from feces and grass, but not between L3 recovered from the grass base and apex. These results show that the region’s climate favors the development and survival of infective cyathostomin larvae throughout the year, with a greater number of larvae during the dry season.A disponibilidade de larvas de ciatostomíneos está diretamente relacionada com as condições climáticas de cada região. Para avaliar o comportamento das larvas infectantes nos períodos seco e chuvoso em gramínea Brachiaria humidicola, realizou-se um estudo, no período de outubro/2007 a setembro/2008, na região da Baixada Fluminense, RJ, de clima tropical. Amostras de fezes foram coletadas diretamente do reto de equinos naturalmente infectados por ciatostomíneos, no início do período chuvoso (outubro a março e seco (abril a setembro, divididas em quatro amostras de 500 g e depositadas em um canteiro formado por gramínea B. humidicola. Sete dias após o depósito e, posteriormente, a cada 15 dias, amostras de fezes e gram

  20. Efeito de Brachiaria decumbens na herbivoria e no desenvolvimento de duas leguminosas nativas de cerrado Effect of Brachiaria decumbens on herbivory and development of two cerrado native leguminosae species

    Directory of Open Access Journals (Sweden)

    A.C.V. Pires

    2012-12-01

    Full Text Available Este estudo avaliou o impacto da presença da gramínea exótica (Brachiaria decumbens na herbivoria e no desenvolvimento de plântulas de espécies nativas (Hymenaea stigonocarpa e Dipteryx alata de Cerrado. Para avaliar o impacto da presença da gramínea, 10 blocos em pastagem (antiga área de Cerrado na Embrapa Gado de Corte (Campo Grande-MS foram demarcados em janeiro de 2009. As gramíneas foram mantidas intactas em metade dos blocos e, na outra metade, foram removidas. Em cada tratamento, foram avaliados a herbivoria, a altura e o diâmetro na altura do solo (DAS de 25 plântulas de cada espécie ao longo do ano. O conteúdo de carbono, nitrogênio e água das folhas também foi quantificado. Plântulas de Hymenaea stigonocarpa nos tratamentos com gramínea tiveram maior taxa de crescimento em diâmetro que as plântulas no tratamento sem gramíneas. As plântulas de Dipteryx alata que estavam no tratamento sem gramíneas tiveram maiores taxas de crescimento em altura que as do tratamento com gramíneas. Houve diferença na taxa de herbivoria de D.alata entre os tratamentos. As plântulas das duas espécies que estavam no tratamento com gramínea mostraram maiores concentrações de carbono e menores de água. O conteúdo de nitrogênio foliar foi maior no tratamento com gramíneas que no sem gramíneas em D.alata; já o nitrogênio em H. stigonocarpa não variou entre os tratamentos. Esses resultados mostram que cada espécie nativa possui distintas respostas fisiológicas e suscetibilidade à herbivoria em ambientes sob competição de recursos com a gramínea exótica, B. decumbens.This study evaluated the impact of the presence of the exotic grass (Brachiaria decumbens on the herbivory and development of seedlings of native species (Hymenaea stigonocarpa and Dipteryx alata of the Cerrado. Thus, 10 pasture plots (former Cerrado at the Embrapa Gado de Corte (Campo Grande-MS were demarcated in January 2009. The grasses were kept intact

  1. Forage intake and botanical composition of feed for cattle fed Brachiaria/legume mixtures Consumo e composição da forragem ingerida por bovinos alimentados com Brachiaria e uma leguminosa

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    Robert Macedo

    2010-08-01

    Full Text Available A key contribution to study the cycling of nutrients in soil/plant/animal systems is the evaluation of the consumption of forage and their nutrients by cattle. The objective of this study was to test techniques to evaluate faecal production, in vitro digestibility, forage consumption and the proportion of legume in the acquired diet. Five Zebu steer calves were confined and fed five diets of different combinations of Brachiaria dictyoneura and Desmodium ovalifolium. All quantities of faeces were collected per animal and these values were found to compare favourably with those derived from using the chromium oxide technique. In vitro digestibility ranged from 7 to 10% higher than the actual in vivo digestibility. Faecal samples from steers fed with diets with 25% or more of grass in the mixture were found to be depleted in δ13C between 1.7 and 2.1‰, but no depletion was observed when the diet was 100% D. ovalifolium. There was a positive linear regression (r² = 0.97*** of the δ13C of the diet with the δ13C of faeces, but if the acquired diet contained a very high proportion of legume, the legume content could be underestimated by as much as 10%. None of the internal indicators, such as lignin or ash content of the diets, were useful to predict feed intake, but the chromium oxide external indicator performed satisfactorily. The 13C analysis of the faeces was an effective predictor of the proportion of the legume in the consumed diet.Uma contribuição fundamental para o estudo da ciclagem de nutrientes no sistema solo/planta/ animal é a avaliação do consumo pelo gado de forragem e dos nutrientes nela contidos. Testaram-se, sob condições controladas, técnicas para avaliar a produção fecal, digestibilidade in vitro, consumo de forragem e a proporção de leguminosa ingerida na dieta. Cinco novilhos de Zebu foram confinados e alimentados com quantidades conhecidas de cinco rações com diferentes proporções de Brachiaria dictyoneura e

  2. Efeito da suplementação sobre a digestibilidade dos nutrientes e desempenho de bezerros lactentes mantidos em pastagens de Brachiaria brizantha = Effect of supplementation on nutrient digestibility and performance of lactating calves fed with Brachiaria brizantha pastures

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    Alexandre Amstalden Moraes Sampaio

    2010-01-01

    Full Text Available Foi avaliado o efeito da suplementação e do tipo do suplemento sobre adigestibilidade dos nutrientes e o desempenho de bezerros Canchim lactentes mantidos em pastagem de Brachiaria brizantha cv. Marandu durante os meses de fevereiro a maio. Os tratamentos foram: sem e com suplementação em creep-feeding com concentrado proteico, comconcentrado energético e com concentrado energético-proteico. Em quadrado latino, foi avaliada a digestibilidade dos nutrientes, utilizando-se quatro bezerros mantidos em baias individuais, recebendo feno da mesma forrageira e com mamadas controladas duas vezes ao dia. O desempenho foi avaliado em delineamento inteiramente casualizado, sendo os 23 bezerros mantidos junto com as matrizes. A suplementação com concentrado energético-proteico determinou melhor ingestão e aproveitamento dos nutrientes (65% de digestibilidade da matéria seca, desempenho dos bezerros (ganhos de peso de 0,98 kg dia-1 e manutenção do peso e das reservas corporais das matrizes. A utilização de suplemento proteico não mostrou bons resultados, sendo estes inferiores inclusive ao desempenho dos bezerros que não receberam suplementação, 0,56 e 0,77 kg dia-1, respectivamente. O desempenho dos bezerros no tratamento sem suplementação foi semelhante àqueles que receberam suplemento energético, porém asmatrizes tiveram redução mais acentuada do peso corporal e das reservas energéticas. A suplementação com concentrado energético-proteico para bezerros lactentes mantidos em pastagens de Brachiaria brizantha cv. Marandu no início da seca mostrou ser uma técnica quebeneficia o desempenho desses animais e das matrizes.This study evaluated the effect of supplementation and the type of supplement on nutrient digestibility and performance of lactating calves fed with Brachiara brizantha cv. Marandu pasture from February to May. The treatments were: supplementation in creep-feeding with protein concentrate, with energy concentrate

  3. Soil bulk density and biomass partitioning of Brachiaria decumbens in a silvopastoral system Densidade do solo e partição de biomassa de Brachiaria decumbens em um sistema silvopastoril

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    Domingos Sávio Campos Paciullo

    2010-10-01

    Full Text Available Shade in silvopastoral systems improves the thermal comfort of animals, but it may also affect the pasture productivity and can contribute to soil compaction in the shaded areas due to the increase in the number of animals looking for comfort. The effect of grazing at various distances from tree rows (under the tree canopy, at 6 and at 12 m away from the trees on the soil bulk density and on the aerial and root biomass of Brachiaria decumbens was evaluated in both the dry and the rainy seasons. The study was carried out on an Orthic Ferralsol in a randomized block design with two replications. Tree rows were composed of Eucalyptus grandis and Acacia mangium species, and the paddocks were submitted to a rotational stocking management, using Holstein (Bos taurus × Zebu (Bos indicus heifers. The shade intensity in the pasture decreased with an increasing distance from the tree row. Soil bulk density did not vary with the distance from the tree row, but varied seasonally, being greater in the rainy season (1.47 g cm-3 than in the dry season (1.28 g cm-3. Green forage and root mass, expressed as dry matter, were lower under the tree canopy and were greater in the rainy season. There were decreases of 22.3 and 41.4% in the aerial and root biomasses, respectively, in the tree rows. The greatest shoot/root ratio for B. decumbens under moderate and intensive shading indicates a modification in the forage biomass allocation pattern that favours the aerial development in detriment of the root system.O sombreamento em sistemas silvipastoris concorre para o conforto térmico dos animais; no entanto pode afetar a produção do pasto e contribuir para a compactação do solo, pelo aumento da concentração de animais nas áreas sombreadas. Avaliou-se o efeito da distância do renque de árvores (sob a copa das árvores, 6 e 12 m de distancia das árvores na densidade do solo e na biomassa aérea e de raízes de Brachiaria decumbens, nas épocas seca e chuvosa

  4. Influência do Fósforo, Micorriza e Nitrogênio no Conteúdo de Minerais de Brachiaria brizantha e Arachis pintoi Consorciados Effect of Phosphorus, Mycorrhizal and Nitrogen on Mineral Content of Brachiaria brizantha - Arachis pintoi Mixture

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    Ívina Paula Almeida dos Santos

    2002-01-01

    Full Text Available O experimento foi conduzido em casa de vegetação com o objetivo de avaliar a influência do fósforo (P, fungos micorrízicos arbusculares (FMA's e nitrogênio (N no acúmulo de minerais na MS da parte aérea de braquiária MG-4 (Brachiaria brizantha cv. MG-4 e amendoim forrageiro (Arachis pintoi cv. Amarillo consorciados, em solo de baixa fertilidade. O delineamento utilizado foi o inteiramente casualizado, num esquema fatorial 5x2x2, sendo cinco doses de P (25, 50, 75, 100 e 200 mg de P/kg de solo, dois tratamentos de inoculação do solo (inoculado e não com o FMA Glomus etunicatum e dois tratamentos de N (com e sem N em cobertura, com quatro repetições. Foi realizado o corte da parte aérea das plantas aos 60 dias após a germinação para a determinação das quantidades acumuladas de N, P, K, Ca, Mg e S na MS da parte aérea. As adubações fosfatada e, principalmente, a nitrogenada provocaram aumento no conteúdo de N, P, K, Ca, Mg e S na braquiária MG-4, não se verificando tal aumento com a micorrização. No amendoim forrageiro, observou-se redução destes minerais com a aplicação de N, ao passo que a micorrização resultou em aumento dos mesmos. Por outro lado, a adubação fosfatada provocou pequeno aumento no acúmulo de minerais na MS da parte aérea do amendoim forrageiro.This experiment was carried out in a greenhouse condition to study the effect of phosphorus, arbuscular mycorrhizal fungi and nitrogen on mineral accumulation in braquiaria MG-4 (Brachiaria brizantha cv. MG-4 above ground forage DM and peanut (Arachis pintoi cv. Amarillo mixture, in soil of low fertility. The experimental design was a completely randomized in a 5x2x2 factorial arrangement, with five P rates (25, 50, 75, 100 and 200 mg/kg of soil, two inoculations (inoculated and no inoculated and two levels of N (with and without N, with four replicates. The harvest of the above ground parts of plants was at 60 days after seed germination to determine

  5. Dry Bean Morpho-Physiological Responses to Gradual Weed Biomass Accumulation

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    Hossein GHAMARI

    2013-02-01

    Full Text Available Field study was carried out in 2011 in west of Iran to assess responses of dry bean (Phaseolus vulgaris L. morpho-physiological traits to gradual weed biomass accumulation. The treatments consisted of two different periods of weed interference, which weeds either infested the plots or removed for an increasing duration of time (0, 10, 20, 30, 40, 50 days after crop emergence. Relative dominance and relative importance of weed species fluctuated over the crop cycle. As the duration of weed interference was increased, a declining trend of crop growth rate (CGR was observed. When weeds were allowed to compete with crop throughout the crop cycle, maximum value of CGR was decreased from 25.57 g m-2 days in full season weed free treatment to 16.78 g m-2 days in full season weed infested treatment. Effect of treatments on leaf area index (LAI was significant. Weed removal increased LAI but it could not significantly affect this trait, at the early of growing season. Weed interference caused a significant reduction on number of branches. The minimum number of branches was registered in full season weed infested treatment (2.58 branches per plant, while the maximum one was observed in the full season weed free treatment (4.25 branches per plant. Weed competition severely reduced crop yield. At 10 and 20 days after crop emergence, weed infestation could not significantly affect the yield. A negative relationship between weeds’ dry matter accumulation and LAI as well as number of branches was observed which signify the vulnerability of these morpho-physiological traits to weed competition.

  6. Identificação de isolados de Azospirillum amazonense associados a Brachiaria spp., em diferentes épocas e condições de cultivo e produção de fitormônio pela bactéria Identification of Azospirillum amazonense isolates associated to Brachiaria spp. at different stages and growth conditions, and bacterial plant hormone production

    Directory of Open Access Journals (Sweden)

    F. B. Reis Junior

    2004-02-01

    Full Text Available Existem evidências de que pastagens formadas por algumas espécies do gênero Brachiaria poderiam beneficiar-se com o processo de fixação biológica do nitrogênio atmosférico (FBN, garantindo a estas pastagens maior longevidade. Dentre as bactérias diazotróficas encontradas em associação com estas gramíneas forrageiras, destaca-se a espécie Azospirillum amazonense. Neste trabalho, objetivou-se verificar a influência da espécie de Brachiaria, manejo da pastagem e sazonalidade sobre as populações de A. amazonense associadas às raízes destas plantas. Diferentes pastagens (B. humidicola, B. decumbens e B. brizantha foram introduzidas em regiões do ecossistema Cerrado e de Mata Atlântica. Foram avaliados dois sistemas de manejo com diferentes taxas de lotação, e as coletas foram realizadas em diferentes épocas do ano. As populações de A. amazonense foram quantificadas e a identidade dos isolados confirmada, assim como sua capacidade de produção de fitormônios tipo AIA (ácido 3-indol acético em meio de cultivo. Isolados de A. amazonense foram obtidos a partir de amostras de raízes das três espécies de Brachiaria avaliadas. Estimativas das populações desta bactéria variaram de 10³-10(7 células g-1 de raízes. Em amostras do ecossistema Cerrado, a época de coleta apresentou efeito significativo sobre a população destas bactérias. Os dados da região de Mata Atlântica mostraram que plantas de Brachiaria de diferentes espécies e pastagens sob diferentes taxas de lotação podem apresentar números populacionais distintos associados às suas raízes. A técnica de análise de restrição do DNA ribossomal amplificado (ARDRA confirmou a identidade de todos os isolados avaliados. Estes isolados foram capazes de produzir fitormônios tipo AIA.There is evidence that pastures formed by some species of the genus Brachiaria could be benefited by the biological nitrogen fixation process (BNF, which would give these

  7. Evaluation of multi-species weed competition and weeds population dynamic in corn Zea mays L. field

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    S Mijani

    2016-05-01

    Full Text Available In order to examine the multi-species weed competition in corn field an experiment as an interval mapping was carried out at the Agricultural Research field of Ferdowsi University of Mashhad during growing season 2009-2010. At 3-4 leafy stages of corn, 20 non-destructive quadrates determine and the density of weeds was counted separately. At the same time, 20 destructive quadrates determine and in addition of counting number of plants, leaf area index and dry weight of each species were recorded separately. By using data from previous section, hyperbolic functions were fitted. In these functions number of species serve as the independent variable, weight or leaf area was considered as the dependent variable. With the help of these functions and leaf dry weight of each species was determined for non-destructive quadrates at this stage. Relative leaf area at early season as independent variables and natural logarithm of individual plant weight at later season as dependent variable in a multiple linear regression was fitted to obtain the interspecies competition coefficients. Based on ln of weight of single plant equation the weed interference effects on the corn yield can be divided into two groups: inhibition (negative sign and stimulation (positive sign. Among all weeds, night shade (Solanum nigrum L., redroot pigweed (Amaranthus retroflexus L. and lambsquarter (Chenopodium album L. had positive effects on corn yield, respectively. In fact, these weeds had competition and negative impacts on other weeds and reduced their competition power with corn and caused facilitation role on corn yield. At the end of growing season of corn, population of lambsquarter and Common purslane (Portulaca oleracea L. decreased while population of barnyard grass(Echinochloa crus-galli L., redroot pigweed and night shade increased.

  8. Crescimento de espécies de Brachiaria sob déficit hídrico e alagamento a campo Effect of water deficit and flooding on the growth of Brachiaria species in the field

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    Jorge Luiz Schirmer de Mattos

    2005-06-01

    Full Text Available Dois experimentos foram conduzidos, sendo um instalado em área de encosta e outro em área de baixada. Objetivou-se avaliar a tolerância à seca e ao alagamento de três espécies comerciais de Brachiaria (B. decumbens cv. Basilisk, B. brizantha cv. Marandu e B. mutica e três acessos (B. brizantha B-11, B. humidicola cv. Tupi e B. dictyoneura, a partir de suas características morfogênicas, produtivas e relações hídricas. O delineamento experimental foi o de blocos ao acaso, com seis repetições. As parcelas, com 4 m² de área total, foram constituídas de oito linhas de 2 m de comprimento, com espaçamento entre linhas de 0, 25 m. Dezenove dias após corte de uniformização, a área localizada na baixada foi submetida ao alagamento de uma lámina d'àgua de 56 mm de água, por 30 dias; simultaneamente, suspendeu-se a irrigação na área de encosta sob déficit hídrico. O alagamento foi mais prejudicial às características morfogênicas que déficit hídrico. Enquanto a taxa de alongamento foliar de todas as espécies foi mais baixa sob alagamento, as taxas de aparecimento e senescência foliares responderam ao estresse hídrico conforme a espécie. A taxa de aparecimento de folhas foi mais comprometida pelo alagamento apenas em B. dictyoneura, B. mutica e B. brizantha cv. Marandu. As maiores taxas de senecência de folhas ocorreram sob alagamento, particularmente em B. decumbens, B. brizantha cv. Marandu e B-11. Os estresses hídricos tiveram efeitos diferenciados sobre as características produtivas das espécies. A produção de biomassa verde aérea foi maior em B-11 sob regime de déficit hídrico, enquanto em B. dictyoneura e B. mutica, observou-se tendência de valores mais altos sob regime de alagamento. O índice de área foliar foi mais alto sob deficit hídrico, apenas em B. brizantha Marandu e B-11. A população de perfilhos basilares foi maior sob alagamento apenas em B. dictyoneura.Two experiments were carried out

  9. Armazenamento de sementes de braquiária peletizadas e tratadas com fungicida e inseticida Brachiaria coated seed storage treated with fungicide and insecticide

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    Carlos Eduardo Pereira

    2011-12-01

    Full Text Available A qualidade de sementes é fundamental para o sucesso da formação de pastagem, de forma que é importante viabilizar tecnologias para elas. Assim, objetivou-se com este trabalho avaliar o desempenho de sementes de Brachiaria decumbens peletizadas e tratadas com fungicida e inseticida, durante o armazenamento. As sementes foram tratadas com thiabendazol na dosagem de 200mL 100kg-1 de sementes, com fipronil na dosagem de 500mL 100kg-1 de sementes e com a mistura de ambos (nas mesmas dosagens e parte não foi submetida a esses tratamentos (testemunha. Posteriormente, as sementes foram peletizadas utilizando-se uma mistura de areia + microcelulose e cola Cascorex - PVA (20%, as quais em seguida foram armazenadas em condições ambientais em armazém convencional (temperatura e umidade relativa do ar média de 21,9°C e 68%, respectivamente, durante 12 meses. As sementes foram avaliadas inicialmente e a cada quatro meses com as seguintes avaliações: teor de água, teste de germinação, índice de velocidade de germinação, teste de emergência e índice de velocidade de emergência. A peletização das sementes de Brachiaria decumbens com areia e microcelulose prejudica a porcentagem e velocidade de germinação, bem como a emergência de plântulas durante o armazenamento. Sementes de Brachiaria decumbens cv. 'Basilisk' tratadas com fipronil, thiabendazol, ou com ambos, não devem ser armazenadas por mais de oito meses.The quality of seed is crucial to the success of pasture formation. Thus the aim of this research was to evaluate the performance of Brachiaria decumbens seeds pelleted and treated with fungicides and insecticides during storage. The seeds were treated with thiabendazole at a dosage of 200mL 100kg-1 of seeds, with fipronil at a dosage of 500mL 100kg-1 of seeds and a mixture of both (in the same dosages and some was not subjected to such treatment (control. Subsequently the seeds were coated using a mixture of sand

  10. Diferenciação de espécies daninhas aquáticas pela análise multivariada de caracteres estruturais foliares Differentiation of aquatic weeds by multivariate analysis of foliar structural characters

    Directory of Open Access Journals (Sweden)

    N.V. Costa

    2006-01-01

    Brachiaria mutica, Brachiaria subquadripara, Panicum repens, Eichhornia crassipes, Heteranthera reniformis, Typha subulata, and Enhydra anagallis. Leaf blade samples were collected, fixed in FAA 50, infiltrated in glycol metacrylate resin, cut transversally with 8 mm thickness, and stained with toluidine blue. Structural characters in vein and internerval regions were quantitatively evaluated (% for adaxial and abaxial epidermis, vascular bundle, vascular bundle sheath, esclerenchyma, parenchyma, and spongy aerenchyma. Leaf thickness, stomata and trichome number were determined at the internerval region. The quantitative structural characters of the leaf were submitted to Clusters Analysis and Principal Components Analysis. Three groups were formed according to similarity levels: group 1 - B. mutica, B. subquadripara, and P. repens (Poaceae; group 2 - E. crassipes and H. reniformis (Pontederiaceae, and E. anagallis (Asteraceae; group 3 - only for T. subulata (Typhaceae. The structural characters with high discriminatory degree were: adaxial epidermis (internerval region; abaxial epidermis, vascular bundle, vascular bundle sheath, esclerenchyma and spongy aerenchyma (middle vein and internerval region; leaf thickness; and stomata number. The quantitative structural characters allowed the differentiation of these aquatic weed species during the vegetative period.

  11. Weed control based on real time patchy application of herbicides using image analysis as a non-destructive estimation method for weed infestation and herbicide effects

    DEFF Research Database (Denmark)

    Asif, Ali

    There is an increasing concern about excessive use of herbicides for weed control in arable lands. Usually the whole field is sprayed uniformly, while the distribution of weeds often is non-uniform. Often there are spots in a field where weed pressure is very low and has no significant effect...... on crop yield. The excessive use of spraying can potentially be reduced by spraying only those parts of the field where it has economic importance. The competition relation between weeds and crop was ana-lyzed in context of real time patch spray. A non-destructive image analysis method was developed...

  12. Weed-Species Abundance and Diversity Indices in Relation to Tillage Systems and Fertilization

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    Ilias S. Travlos

    2018-04-01

    Full Text Available Weeds pose a major threat to world agriculture by reducing detrimentally crop yield and quality. However, at the same time, weeds are major interacting components of the agroecosystems. Abundance and diversity of weeds vary significantly among the several communities. In order to evaluate each community's structure and the interactions among them, several population indices are used as key tools. In parallel, various cultivation and land management strategies, such as tillage and fertilization, are commonly used in terms of integrated weed management. Estimating the response of weed species on those practices is crucial for both biodiversity maintenance and alternative weed control methods. Many experiments have confirmed the fundamental role of tillage intensity and nutrition supply in weed species' abundance and diversity. For instance, in some studies, the abundance of perennial weeds was doubled under reduced tillage intensity. In addition, higher values of Shannon-Weiner and Pielou indices were reported in the PK fertilization treatment compared to the control and NK fertilization treatments. The objective of this paper is to provide a brief overview of the key results of these experiments and summarize the part of the literature related to the effect of tillage systems and fertilization on weed species abundance and diversity. Such knowledge could contribute to the sound design and implementation of integrated weed management programs which in turn may lead to a decrease in the density of serious and noxious weeds and an increase in the overall balance of agroecosystems.

  13. Efficacy of Maister OD (Foramsulfuron + Idosulfuron a New Herbicide in Controlling Weeds of Corn Fields

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    J. Abdi

    2012-07-01

    Full Text Available To evaluate the efficacy of a new herbicide Foramsulfuron +Idosulfuron (Maister OD against other herbicides in corn fields, this experiment was fulfielld in 2010 at Mahidasht, Research Center of Agriculture and Natural Resources of Kermanshah, Iran. It was concucted in randomized complete block design with four replications and 11 treatments. In this experiment, three doses of herbicides (38.75, 46.5 and 54.25 g/ha including foramsulfuron + idosulfuron along with Nicusulfuron, ForamSulfuron, Rimsulfuron, Foramsulfuron + Rimsulfuron , Bromicid + hand weeding narrow leaf weeds, Bromicid + Nicusulfuron and U46 + hand weeding of narrow leaf weeds and a complete weeding as the control treatments were investigated. Weeds present in the field were Xanthium stromarium,Chenopedium album, Portulaca oleracea, Sorgum halepense and Setaria virdis. The results of this study showed that doses 38.75 and 46.5 g/ha of herbicide foramsulfuron + idosulfuron after treatments of Bromicid + Nicusulfuron and, Bromicid + narrow leaf weed, hand weeding respectively could control 90 and 86 % of weeds in corn field and increase its yields significantly. Because there are presently few registered herbicide available in Iran, necessity of finding proper herbicides to control weeds in corn field and based on the results oblained from this experiment it seems using 46.5 and 38-75 grams per hectare respectively of foramsulfuron + idosulfuron could be a better option than other herbicides to control weeds in corn fields and increase its seed yield.

  14. Herbicide-resistant crops: utilities and limitations for herbicide-resistant weed management.

    Science.gov (United States)

    Green, Jerry M; Owen, Micheal D K

    2011-06-08

    Since 1996, genetically modified herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, have transformed the tactics that corn, soybean, and cotton growers use to manage weeds. The use of GR crops continues to grow, but weeds are adapting to the common practice of using only glyphosate to control weeds. Growers using only a single mode of action to manage weeds need to change to a more diverse array of herbicidal, mechanical, and cultural practices to maintain the effectiveness of glyphosate. Unfortunately, the introduction of GR crops and the high initial efficacy of glyphosate often lead to a decline in the use of other herbicide options and less investment by industry to discover new herbicide active ingredients. With some exceptions, most growers can still manage their weed problems with currently available selective and HR crop-enabled herbicides. However, current crop management systems are in jeopardy given the pace at which weed populations are evolving glyphosate resistance. New HR crop technologies will expand the utility of currently available herbicides and enable new interim solutions for growers to manage HR weeds, but will not replace the long-term need to diversify weed management tactics and discover herbicides with new modes of action. This paper reviews the strengths and weaknesses of anticipated weed management options and the best management practices that growers need to implement in HR crops to maximize the long-term benefits of current technologies and reduce weed shifts to difficult-to-control and HR weeds.

  15. Effect of long-term fertilisation on the weed community of a winter wheat field.

    Science.gov (United States)

    Jiang, Min; Liu, Tao; Huang, Niansheng; Shen, Xinping; Shen, Mingxing; Dai, Qigen

    2018-03-05

    Effects of fertilisation and other management techniques on a weed community were evaluated during wheat growth in a rice-wheat cropping system. Fertiliser treatments were C0 (C means chemical, C0 means zero chemical fertiliser.), CN (N fertiliser), CNK (N plus K fertiliser), CNPK (N plus P and K fertiliser), CNP (N plus P fertiliser), and CPK (P plus K fertiliser). Weed density, biomass, and bio-diversity were determined. Redundancy analysis (RDA) was used to investigate the relationship between fertiliser management, weed species, and weed density. The overall weed densities in the C0 and CPK treatments were the greatest during wheat seeding and ripening periods and were significantly greater than densities in the other treatments. N, P and organic matter in soil were highly correlated with weed species and density, whereas K in soil was not significantly correlated with weed species and weed density. N fertiliser significantly reduced weed density. Balanced fertilisation maintained weed species richness and resulting in a high yield of wheat. CNPK application reduced weed damage and improved the productivity and stability of the farmland ecosystem.

  16. The main weed species and their control in oilseed crops in Finland

    Directory of Open Access Journals (Sweden)

    J. SALONEN

    2008-12-01

    Full Text Available A survey of weeds in spring-sown oilseed crops (Brassica rapa ssp. oleifera and Brassica napus ssp. oleifera was conducted in southern and central Finland during 2007–2009, representing the first such extensive investigation in the country. The occurrence of the most abundant weed species in oilseeds was surveyed in 429 fields. In the fields with moderate or high weed infestation, 1–6 harmful weed species were recorded by visual observation according to their biomass production. About 40 weed species were recorded, the most predominant being Chenopodium album, Galeopsis spp., Galium spurium, Sonchus arvensis and Tripleurospermum inodorum. Elymus repens was the only major grass weed. Chemical weed control of broad-leaved weeds had been practised in 53% of the fields, resulting in relatively good control. In addition, both selective graminicides and glyphosate were used to control E. repens. Mechanical weed control was not practised in any field. The crop yield level was about 300 kg ha-1 higher in the fields with low weed infestation compared with in the highly infested fields. New promising options to replace the banned herbicide trifluralin are available. Thus, the most harmful weeds, such as C. album, which interferes with the production of high-quality oil for human consumption, can still be effectively controlled.;

  17. Weed competitiveness and yielding ability of aerobic rice genotypes

    NARCIS (Netherlands)

    Zhao, D.L.

    2006-01-01

    Keywords:    Broad-sense heritability; Crop vigour; Genetic correlation; Indirect selection index; Plant erectness; Rice germplasm; Seeding rate; Vegetative growth; Weed-suppressive ability.

  18. Preemergence herbicides on weed control in elephant grass pasture

    Directory of Open Access Journals (Sweden)

    Alexandre Magno Brighenti

    Full Text Available ABSTRACT Elephant grass (Pennisetum purpureum Schum. is an important forage crop that has been proposed as a potential feedstock for bioenergy production. However, weed interference is a major factor limiting elephant grass production. Field experiments were conducted in 2014 and 2015 to evaluate preemergence herbicides for selective weed control in an elephant grass pasture. Herbicide treatments included atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, diuron + hexazinone, sulfentrazone, imazethapyr, and atrazine at label use rates. Weedy and weed-free treatments were included. Atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine did not cause phytotoxicity on elephantgrass 35 days after treatment (DAT. However, diuron + hexazinone and imazethapyr were the most phytotoxic on elephantgrass, resulting in 81 and 70% phytotoxicity in 2014, and 7 and 6% phytotoxicity in 2015 respectively 35 DAT. All treatments provided effective weed control (>81% with the exception of ethoxysulfuron (0 and 11% in 2014 and 2015, respectively, and atrazine (59% in 2014. These results show that atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine were selectives when applied in preemergence in elephant grass pasture.

  19. Glyphosate resistant weeds - a threat to conservation agriculture

    Science.gov (United States)

    Glyphosate-resistant weeds are now present throughout the Southeast. Hundreds of thousands of conservation tillage cotton acres, some currently under USDA Natural Resources Conservation Service (NRCS) conservation program contracts, are at risk of being converted to higher-intensity tillage systems....

  20. Weed Control in White Bean with Various Halosulfuron Tankmixes

    Directory of Open Access Journals (Sweden)

    Nader Soltani

    2014-01-01

    Full Text Available Four field trials were conducted over a three-year period (2011–2013 in southwestern Ontario to evaluate the level of weed control provided by various halosulfuron tankmixes applied preplant incorporated (PPI in white bean. Trifluralin, s-metolachlor, halosulfuron, and imazethapyr applied alone or in combination caused 4% or less visible injury 1 and 4 weeks after emergence (WAE in white bean. Trifluralin, s-metolachlor, halosulfuron, and imazethapyr applied PPI provided 80–96%, 84–95%, 83–100%, and 75–92% control of redroot pigweed; 19–28%, 30–40%, 97–99%, and 73–84% control of common ragweed; 94–96%, 63–82%, 96–100%, and 96–100% control of common lambsquarters; 14-15%, 12–35%, 100%, and 96–97% control of wild mustard; and 96–97%, 95–97%, 53–56%, and 80–82% control of green foxtail, respectively. The two- and three-way tankmixes of halosulfuron with trifluralin, s-metolachlor, or imazethapyr provided 85–100% control of redroot pigweed, 90–98% control of common ragweed, 97–100% control of common lambsquarters, 100% control of wild mustard, and 93–98% control of green foxtail. Weed density, weed biomass and white bean seed yields reflected the level of visible weed control.

  1. 611 A QUANTITATIVE ESTIMATE OF WEEDS OF SUGARCANE ...

    African Journals Online (AJOL)

    Osondu

    Abstract. A survey was conducted in the sugarcane fields of Unilorin Sugar Research Institute, Ilorin in the southern. Guinea savanna agro-ecological zone of Nigeria during 2011 and 2012 cropping seasons with an objective to identify the current status of prevalent weeds in rainfed and irrigated sugarcane fields. A.

  2. Critical Period of Weed Interference in Rainfed and Irrigated ...

    African Journals Online (AJOL)

    Field trials were conducted to assess the critical period of weed interference in tomato on the farm of the Institute of Agricultural Research, Samaru (11011\\'N, 07038\\'E) in the Northern Guinea Savannah ecological zone of Nigeria in 1989 and 1990 wet seasons and at the Irrigation Research Station of the Institute of ...

  3. Efficacy of primextra gold in controlling weeds of melon ( Citrillus ...

    African Journals Online (AJOL)

    A field experiment was conducted in the Center of Ecological Studies, University of Port Harcourt, Rivers State to evaluate the efficacy of Primextra Gold (290g /l S – Metalochlor and 370g/l Atrazine) herbicide in controlling weeds in melon and to determine its safety for use in melon. The experiment was carried out between ...

  4. Effects of Weed Control and Cow Dung Manure on Growth ...

    African Journals Online (AJOL)

    Field trials were conducted during the 2006, 2007 and 2008 rainy seasons at the Institute for Agricultural Research Samaru, in the Northern guinea savanna zone of Nigeria to evaluate the effects of weed control and cow dung manure treatments on growth of Quality Protein Maize. The trial consisted of factorial ...

  5. Economic potentials of oil palm products and weed control on ...

    African Journals Online (AJOL)

    A study was carried out at the Research Farm of National Root Crops Research Institute Umudike, southeastern Nigeria (05o, 29'N, 07o 33'E and 122 m above sea level), in 2015 and 2016 cropping seasons to study the economic potentials of oil palm products and weed control on sustainable turmeric production and some ...

  6. Larvicidal Properties of Datura Stramonium (Jimson Weed) and ...

    African Journals Online (AJOL)

    Extracts of the leaf of Nicotiana tabaccum (Tobacco) (L) in the family. Solanaceace and the root of Datura Stramonium (Jimson weed) in the family. Solanaceace, were prepared from plant materials collected within Ekiti State, Nigeria. With Datura stramonium extract treatment, there was less than 50% mortality of larvae on ...

  7. Soil weed seedbank dynamic and allelopathic potential of Tithonia ...

    African Journals Online (AJOL)

    The phenomenon of allelopathy is receiving increased attention as a possible alternative weed control method that is environment-friendly when compared with the use of herbicides with a wide range of toxic side effects which pose potential hazards to the environment. This study was designed to estimate the distribution of ...

  8. Exploring cost-effective maize integrated weed management ...

    African Journals Online (AJOL)

    Several production constraints have led to low yields (< 2.5 t ha-1) in maize (Zea mays L.) inUganda, among which are weeds. This study investigated the most cost-effective integrated weedmanagement (IWM) approach in maize in eastern Uganda. An experiment was conducted atIkulwe station, Mayuge in 2011 and 2012 ...

  9. Management of parthenium weed by extracts and residue of wheat ...

    African Journals Online (AJOL)

    This study was carried out to investigate the prospects of using methanolic extracts and residue of wheat (Triticum aestivum L.) for the management of parthenium (Parthenium hysterophorus L.), one of the world's worst weeds. In a laboratory bioassay, the effect of methanol extracts of 1, 2, 3, 4 and 5% (w/v) concentrations of ...

  10. The effects of exotic weed Flaveria bidentis with different invasion ...

    African Journals Online (AJOL)

    A new exotic weed, Flaveria bidentis, is spreading in central China where it forms dense monospecific patches modifying the structure of different native ecosystems and threatening native aboveground biodiversity. However, little is known about the consequences of such an invasion for soil bacterial community, especially ...

  11. Weeding, Wine, and Cheese: Enticing Faculty to Cull a Collection

    Directory of Open Access Journals (Sweden)

    Judith Anne Koveleskie

    2014-11-01

    Full Text Available Remodeling of a building and decreased shelf space motivated faculty and staff to complete a long overdue weeding project in a small university library. Librarians used social media, internal communication, and personal contact to motivate faculty. Every effort was made to reuse and recycle discarded materials. The result was a streamlined collection and a much improved learning space.

  12. The Lean Reference Collection: Improving Functionality through Selection and Weeding.

    Science.gov (United States)

    Nolan, Christopher W.

    1991-01-01

    Discusses references collections in academic libraries and offers guidelines for placing materials in a reference collection that focus on their suitability for true reference functions and the expected frequency of use. Problems with poorly managed collections are discussed, and the importance of selection policies and weeding are emphasized. (37…

  13. Impact of preceding crop on alfalfa competitiveness with weeds

    Science.gov (United States)

    Organic producers would like to include no-till practices in their farming systems. We are seeking to develop a continuous no-till system for organic farming, based on a complex rotation that includes a 3-year sequence of alfalfa. In this study, we evaluated impact of preceding crop on weed infest...

  14. 7 CFR 201.52 - Noxious-weed seeds.

    Science.gov (United States)

    2010-01-01

    ... 64499, Dec. 14, 1994] germination tests in the administration of the act ... 7 Agriculture 3 2010-01-01 2010-01-01 false Noxious-weed seeds. 201.52 Section 201.52 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT...

  15. Tillage as a driver of change in weed communities

    NARCIS (Netherlands)

    Armengot, L.; Blanco-Moreno, J.M.; Bàrberi, P.; Bocci, G.; Carlesi, S.; Aendekerk, R.; Berner, A.; Celette, F.; Grosse, M.; Huiting, H.; Kranzler, A.; Luik, A.; Mäder, P.; Peigné, J.; Stoll, E.; Delfosse, P.; Sukkel, W.; Surböck, A.; Westaway, S.; Sans, F.X.

    2016-01-01

    The adoption of non-inversion tillage practices has been widely promoted due to their potential benefits in reducing energy consumption and greenhouse emissions as well as improving soil fertility. However, the lack of soil inversion usually increases weed infestations and changes the composition

  16. PRODUCTION OF BIOG S FROM COW DUNG, WEEDS ND ...

    African Journals Online (AJOL)

    USER

    2017-05-26

    May 26, 2017 ... Ethiopian Journal of Environmental Studies & Management 10(4): 482 – 491, 2017. ISSN:1998- ... Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, ... Biogas production was carried out using cow dung, weeds, orange peelings and corn cob. ... This work is therefore aimed to.

  17. Influence of weed control methods, poultry manure and planting ...

    African Journals Online (AJOL)

    Influence of weed control methods, poultry manure and planting pattern on growth and yield attributes of maize (Zea mays l.) in the northern Guinea Savannah zone of Nigeria. M.S. Bature, D.B. Ishaya, M.A Mahadi, A.I Sharifai, A.A Muhammed, A.H Hassan, H.J Jibril, L Goma, G.M Munir ...

  18. Weed Control with Cover Crops in Irrigated Potatoes

    Directory of Open Access Journals (Sweden)

    G.H. Mehring

    2016-01-01

    Full Text Available Field experiments at Oakes, ND, USA in 2010 and Carrington, ND, USA in 2011 were conducted to evaluate the potential for cover crops grown in the Northern Great Plains, USA in order to reduce weed emergence and density in irrigated potatoes. Treatments included five cover crop treatments and three cover crop termination treatments. Termination of cover crops was done with glyphosate, disk-till, and roto-till. Cover crop biomass accumulation was greatest for rye/canola and triticale at Oakes, and hairy vetch and hairy vetch/rye at Carrington. Cover crop and termination affected weed control 14, 29, and 51 days after planting (DAP at Oakes. Weed control at Carrington was at least 90% for all cover crop and termination treatments at all three evaluation timings. Marketable yield at Oakes was greater when roto-till was used to terminate the cover crops compared with disk-till or herbicide, which is beneficial for organic systems where herbicides are not used. Marketable yield at Carrington was not affected by cover crop or termination treatments. Results suggest that cover crops can successfully be integrated into irrigated potato production for weed control with yields equal to no cover crop, and with attention to potential mechanical difficulties.

  19. WEED CONTROL AND BORON NUTRITION ON Eucalyptus IN SILVOPASTORAL SYSTEM

    Directory of Open Access Journals (Sweden)

    Alexandre Magno Brighenti

    2015-04-01

    Full Text Available The objective of this study was to evaluate the control of weeds in the rows of eucalyptus (Eucalyptus urograndis with herbicides applied singly or combined with boron (B, as well as, the response of Eucalyptus plants to this micronutrient. The experiments were carried out in a split-plot with randomized complete block design, with three replicates. Six treatments were applied to the plots: (i weeded control, (ii control without weeding, (iii glyphosate (1080 g ae ha-1 + chlorimuron-ethyl (10 g ai ha-1 + 0.05% v / v mineral oil, (iv glyphosate (1080 g ae  ha-1 + isoxaflutole (112.5 g ai ha-1,  (v glyphosate (1080 g ae ha-1 and  (vi oxyfluorfen (480 g ai ha-1. The sub-plots consisted of the absence or presence of 4 kg of boric acid (H3BO3 - 17% B in 100 L of water. The addition of boric acid in the solution containing the herbicides did not affect the weed control. There was an increase in boron content in the soil and consequently an increase in the boron levels in the eucalyptus leaves. The combined application of herbicides plus boric acid is perfectly suitable for preventing dry of the pointer on eucalyptus plants. Keywords: Eucalyptus urograndis; chemical control; herbicides; micronutrients; Urochloa decumbens.

  20. Herbaceous weed control in loblolly pine plantations using flazasulfuron

    Science.gov (United States)

    Andrew W. Ezell; Jimmie L. Yeiser

    2015-01-01

    A total of 13 treatments were applied at four sites (two in Mississippi and two in Texas) to evaluate the efficacy of flazasulfuron applied alone or in mixtures for providing control of herbaceous weeds. All sites were newly established loblolly pine (Pinus taeda L.) plantations. Plots were evaluated monthly until 180 days after treatment. No phytotoxicity on pine...

  1. Funding needed for assessments of weed biological control

    Science.gov (United States)

    John L. Maron; Dean E. Pearson; Stephen M. Hovick; Walter P. Carson

    2010-01-01

    Invasive non-native plants are a serious economic and ecological problem worldwide, and major efforts are therefore devoted to reducing weed abundance in agricultural and natural settings. Effective options for reducing invasive abundance and spread are few, although one common approach is biological control - the introduction of specialist herbivores or pathogens from...

  2. Vermicomposting and anaerobic digestion – viable alternative options for terrestrial weed management – A review

    Directory of Open Access Journals (Sweden)

    Biswanath Saha

    2018-03-01

    Full Text Available The management of terrestrial weed is of great concern for the scientific community as these weeds cause adverse effect in different ecosystems like forest, agriculture and urban. The widespread of these weeds by their adaptive capability and morphological advancement is difficult to control. Parthenium hysterophorous, Lantana camara, Saccharum spontaneum, Ageratum conyzoides are the weeds that spread all over the world. There are various management practices employed for the control of this weeds. But all of these practices have some drawbacks those are neither environment friendly nor economical. In this paper a review has been done to evaluate various alternative management practices for these terrestrial weeds and to analyze their feasibility. Vermicomposting and anaerobic digestion can be viable alternative option which is cost effective as well. There are few studies regarding vermicomposting and anaerobic digestions of terrestrial weeds are done.

  3. Biology, ecology and management of the invasive parthenium weed (Parthenium hysterophorus L.).

    Science.gov (United States)

    Adkins, Steve; Shabbir, Asad

    2014-07-01

    Parthenium weed (Parthenium hysterophorus L.) is one of the most aggressive invasive weeds, threatening natural ecosystems and agroecosystems in over 30 countries worldwide. Parthenium weed causes losses of crops and pastures, degrading the biodiversity of natural plant communities, causing human and animal health hazards and resulting in serious economic losses to people and their interests in many countries around the globe. Several of its biological and ecological attributes contribute towards its invasiveness. Various management approaches (namely cultural, mechanical, chemical and biological control) have been used to minimise losses caused by this weed, but most of these approaches are ineffective and uneconomical and/or have limitations. Although chemical control using herbicides and biological control utilising exotic insects and pathogens have been found to contribute to the management of the weed, the weed nevertheless remains a significant problem. An integrated management approach is proposed here for the effective management of parthenium weed on a sustainable basis. © 2014 Society of Chemical Industry.

  4. Host Status of Seven Weed Species and Their Effects on Ditylenchus destructor Infestation of Peanut.

    Science.gov (United States)

    De Waele, D; Jordaan, E M; Basson, S

    1990-07-01

    The host suitability to Ditylenchus destructor of seven common weed species in peanut (Arachis hypogaea) fields in South Africa was determined. Based on the number of nematodes per root unit, white goosefoot (Chenopodium album), feathertop chloris (Chloris virgata), purple nutsedge (Cyperus rotundus), jimson weed (Datura stramonium), goose grass (Eleusine indica), khaki weed (Tagetes minuta), and cocklebur (Xanthium strumarium) were poor hosts. Ditylenchus destructor survived on all weed species; population densities increased in peanut hulls and caused severe damage to seeds of peanut grown after weeds. Roots of purple nutsedge left in the soil suppressed populations of D. destructor and root and pod development in peanut grown after the weed. However, nematode populations in peanut hulls and seeds were not suppressed. Some weed species, especially purple nutsedge which is common in peanut fields, can be used to indicate the presence of D. destructor in the absence of peanut.

  5. Caracterización morfológica de 19 accesiones de Brachiaria brizantha en un suelo ácido

    Directory of Open Access Journals (Sweden)

    Yuseika Olivera

    Full Text Available El objetivo de esta investigación fue caracterizar una colección de 19 accesiones de Brachiaria brizantha, procedentes del Centro Internacional de Agricultura Tropical (CIAT, Colombia, que se conserva en el banco de germoplasma de la Estación Experimental de Pastos y Forrajes de Cascajal, Cuba. Se utilizaron descriptores internacionales para gramíneas forrajeras y otros de interés (17 en total, 13 cuantitativos y 4 cualitativos. Las mediciones y observaciones se realizaron en la fase vegetativa y en la reproductiva. El análisis de componentes principales permitió comprobar la existencia de una variabilidad relativamente alta, ya que el acumulado alcanzó 81,22 % en las cinco primeras componentes. En la componente uno, los indicadores con mayor influencia fueron: el número de espículas y de raquis, y el ancho de la inflorescencia. Con la utilización del análisis de conglomerados se diferenciaron seis grupos; en el grupo V, formado por dos accesiones (CIAT-16317 y CIAT-26290, se detectó que estas maximizaron los valores en varios indicadores. Esa variabilidad fenotípica es importante, ya que permite aseverar que se cuenta con un germoplasma de B. brizantha diferenciado, con una riqueza morfológica aceptable, la que se debe conocer para evitar duplicaciones. La caracterización de esta colección permitió comprobar que el mayor grado de diferenciación se encontró en los caracteres cuantitativos. Se sugiere realizar esta actividad como etapa inicial del proceso de evaluación, así como ensayos en los que se evalúen sus potencialidades para indicadores agroproductivos de interés, con fines selectivos.

  6. Effect of root extracts of Brachiaria humidicola on fertilizer nitrogen use efficiency in rice and wheat crops

    International Nuclear Information System (INIS)

    Meena, H.M.; Sachdev, M.S.; Sachdev, Pamila

    2010-01-01

    A pot experiment was conducted in 2009-2010 to study the effect of root extracts of Brachiaria humidicola on fertilizer nitrogen use efficiency in rice and wheat crops. The experiment was conducted with rice (var. Pusa Sugandh-5) as the test crop in kharif season and in rabi season wheat (var. HD-2894) was grown as the test crop with seven treatments. Three level of nitrogen were applied as 30, 60 and 90 mg N kg -1 soil through '1 5 N labelled (NH 4 ) 2 SO 4 as source of N. Recommended dose of P (30 mg P 2 O 5 kg -1 soil) and K (30 mg K 2 O kg -1 soil) through KH 2 PO 4 and KCI were applied. Nitrogen levels and inhibitors had significant effect on rice grain yield. It was maximum 20.37 g pot -1 in case of T 4 (buffer solution extract) and low 13.10 g pot -1 in T 7 (control). Nitrogen uptake in rice straw was found more in BNI treatments as compared to plant based (neem oil coating) and standard nitrification inhibitors. Nitrogen use efficiency in rice plant was highest in case of T 1 (70 % alcohol extract) 41.90 followed by T 4 (buffer solution extract) 41.30. Among the treatments T 5 (neem oil coating) performed better in wheat yield as compared to other treatments. Nitrogen uptake and NUE were maximum in T 3 (salt solution extract) followed by T 5 (neem oil coating) in wheat crop. The maximum nitrogen use efficiency was observed at 60 mg N kg -1 soil as compared to other levels. (author)

  7. Effects of inclusion levels of Indigofera sp. on feed intake, digestibility and body weight gain in kids fed Brachiaria ruziziensis.

    Directory of Open Access Journals (Sweden)

    Andi Tarigan

    2011-03-01

    Full Text Available Twenty weaned male goats (F1 of Boer x Kacang with initial weight of 9 to 12 kg and ages ranging between 3.0 and 4.0 months were used in a study to evaluate the increasing inclusion of Indigofera sp foliage as a source of protein in diets based on chopped Brachiaria ruziziensis for growing goats. Five goats were allocated to one of four treatments in a randomised block design. The diet treatments were: T0 (control diets: B. ruziziensis (100%, T1 (85% B. ruziziensis + 15% Indigofera sp., T2 (70% B. ruziziensis + 30% Indigofera sp. T3 (55% B. ruziziensis + 45% Indigofera sp. all on DM basis. Feed (DM was offered daily at 3.5% BW. The content of CP in Indigofera sp is relatively high (258 g/kg DM, while the NDF (350.7 g/kg DM and ADF (232.2 g/ kg DM concentrations were low. The content of secondary compounds such as total phenol (8.9 g/kg DM, total tannin (0.8 g/kg DM and condensed tannin (0,5 g/kg DM were considerably low. The inclusion of Indigofera sp foliage in diets increased (P 0.05 among the T0,T1 and T2 diets and ranged from 0.08 to 0.09. It is concluded that the foliage of Indigofera sp could be used as feed supplement to supply proteins with low tannin contents. In a grass-based diets Indigofera sp colud be used at the level of 30 to 45% (DM for growing kids.

  8. EVALUACIÓN DE MÉTODOS PARA ERRADICAR HONGOS ENDÓFITOS DE SEMILLAS DE Brachiaria decumbens Stapf

    Directory of Open Access Journals (Sweden)

    Diana Tamayo

    2017-07-01

    Full Text Available La adaptación de plantas a ambientes extremos puede depender de la asociación con hongos endófitos de raíces. Sin embargo, las demostraciones del papel de esos endófitos en las simbiosis son limitadas si no se experimenta con plantas libres de ellos. Este estudio adaptó y evaluó un sistema de germinación masivo de semillas (SGMS para probar métodos de desinfección de semillas de Brachiaria. decumbens en estudios con hongos endófitos de raíces. Con este sistema se evaluaron en semillas métodos de desinfección externa (Soluciones de NaOCl al 5% ó Ca(ClO2 al 7,14%, o calor [60°C] en baño de agua u horno en varios tiempos, e interna (Captan™ y Benomil 50WP (0,1 mg/ml. El SGMS fue adecuado para el desarrollo de plántulas de B. decumbens ya que en cinco días se obtiene abundante material de trabajo (7 a 10 plántulas. Adicionalmente, los métodos de desinfección externa disminuyeron la actividad microbiológica superficial en semillas, comparardo con el control (agua. Aplicar NaOCl (5% resultó en mayor germinación y desarrollo de plántulas, pero no fue posible eliminar estructuras internas de hongos de las raíces, lo que sugiere una relación innata planta–endófito en pasto B. decumbens, que impide obtener plantas libres de endófitos. Algunas implicaciones experimentales son presentadas y discutidas a la luz de estos resultados.

  9. Análise do crescimento de uma cultivar de braquiária em cultivo solteiro e consorciado com cereais Growth analysis of a brachiaria cultivar sole and intercropped with cereals

    Directory of Open Access Journals (Sweden)

    TOMÁS DE AQUINO PORTES

    2000-07-01

    Full Text Available O objetivo deste trabalho foi avaliar o crescimento de braquiária (Brachiaria brizantha cv. Marandu, em consorciação com milho, sorgo, milheto e arroz, bem como da sua rebrota após a colheita dos cereais. A presença dos cereais provocou redução no número de perfilhos, índice de área foliar, massa seca total da parte aérea, massa seca das folhas verdes e dos colmos e taxa de crescimento na braquiária, até a colheita dos cereais. O número de perfilhos alcançou valores maiores do que os da braquiária solteira, após a colheita dos cereais. Os índices de área foliar da braquiária consorciada foram baixos, em comparação com os dos cereais, e a baixa competição, em cobertura foliar, favoreceu a boa produtividade de grãos das culturas. Aos 60-70 dias após a colheita dos cereais, a braquiária rebrotada possuía fitomassa semelhante à da solteira 70 dias após a emergência.The aim of this work was to evaluate the growth of brachiaria (Brachiaria brizantha cv. Marandu intercropped with maize, sorghum, pearl millet and rice and its regrowth after cereals harvest. The presence of cereals caused reduction of tillers number, foliar area index, total dry matter of leaves, dry matter of green leaves and stems, and growth rate of brachiaria up to harvest of cereals. Number of tillers m-2 reached higher values than those of sole cropped brachiaria after the cereals harvest. The leaf area indices of intercropped brachiaria were low, when compared to those of the cereals; and the low competition in the leaf area favoured the good grain yield of the crops. Sixty to seventy days after cereals harvest, brachiaria regrowth showed phytomass similar to that of sole cropped brachiaria 70 days after emergence.

  10. Efeito do metribuzin no controle das plantas daninhas e na produção de grãos em Glycine max (L merrill Effect of metribuzin in weed control and yield of Glycine max (L. merrill

    Directory of Open Access Journals (Sweden)

    J. P. Silva Neto

    1991-01-01

    Full Text Available No ano agrícola 1985/ 86, em Viçosa-MG, foi instalado um ensaio de campo em solo Pdzólico Vermelho-Amarelo argiloso e com 2,9% de matéria orgânica, objetivando estudar o efeito das doses de metribuzin (0,0; 0,35; 0,70 e 1,05 kg i.a.ha-1 no controle de plantas daninhas e na produtividade da soja (Geycine max (L. Merri ll, cv. 'Uber aba'. A maioria das monocotiledôneas que ocorreram na area experimental foi represent ada por Cyperus rotundus L., Brachiaria plantaginea (Link Hitch. e Cynodon dactylon (L. Pers., tendo-se verificado somente redução em Brachiaria planta taginea em virtude do aumento das doses de metribuzin, ocorrendo o mesmo com relação às dicotiledôneas que se fizerem presentes no experimento, com exceção de Oxalis Oxyptera Prop., que não foi controlada nas doses utilizadas. A densidade total médias das invasoras, menos Cyperus rotundus , Oxalis oxyptera e Cynodon dactylon, foi de 141; 124; 62 e 59 plantas . m-2, respectivamente, para as doses de 0,0; 0,35 ; 0,70 e 1,05 kg i.a.ha-1 de metribuzin. A dose de 0,35 kg i.a. de metribuzin.ha-1 foi suficiente para promover a redução da matéria seca da parte aérea das plantas daninhas com a mesma eficiência de controle da dose de 1,05 kg i.a .ha-1 Entretanto, a densidade total médil das invasoras foi reduzida sig nificativamente nas doses de 0,70 e 1,05 kg i.a. de metribuzin.ha-l. O efeito do metribuzin na soja foi evidenciado somente na dose de 1,05 kg i.a.ha-1, com injúria foliar (clorose leve ocorrida até 25 dias, aproximadamente, apôs a emergência das plântulas. Após esse período, houve total recuperação de todas as plantas de soja submetidas a essa dose. A produção de grão se o índice de colheita não foram influencia dos significativamente pelas doses de metribuzin.In order to test doses of metribu zin (0,0; 0,35; 0,70 and 1,05 kg a.i.ha ¹ in weed control and yield of soybe an (Glycine max (L. Merri ll, Uberaba, an experiment was conducted under

  11. Floristic and phytosociology of weeds in pastures in Maranhão State, Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Jaílson Penha Costa

    2016-06-01

    Full Text Available ABSTRACT Knowledge of weed floristic composition and phytosociology are key factors for improving weed management in pastures. Information on weed species that occur in pastures in Northeast Brazil, particularly in Maranhão State is very limited. It is, therefore, important, to search for information to help farmers to control weeds in livestock farming. This paper describes the weed flora diversity and community structure parameters, including density, frequency, abundance and importance value for each weed species found in five pastures of same age and management in Maranhão State, Northeast Brazil. The weed survey was carried out using a wooden frame (80 cm x 30 cm placed randomly on the soil surface 30 times in each pasture (n = 150. Weeds were pulled out, separated by species and counted. The weed flora was represented by 996 individuals, from nine families, 15 genera and 19 species. Weed density within pastures was of 44.3 plants m-2. The weed flora was dominated by species of the Cyperaceae and Poaceae families. The most important weed species based on Importance Value were Eragrostis ciliaris (IV = 32.97, Cyperus rotundus (IV = 31,95, Cyperus luzulae (IV = 27,50, Cyperus sphacelatus (IV = 27,42, Pycreus lanceolatus (IV = 27,33 Cyperus haspan (IV = 25,72 and Eleusine indica (IV = 23,49. Weed diversity, based on Shannon Diversity Index was very high (H' = 4.37 nats ind-1. Our results could lead to improved weed management in pastures in Maranhão State, Northeast Brazil.

  12. Quantifying the effect of crop spatial arrangement on weed suppression using functional-structural plant modelling.

    Science.gov (United States)

    Evers, Jochem B; Bastiaans, Lammert

    2016-05-01

    Suppression of weed growth in a crop canopy can be enhanced by improving crop competitiveness. One way to achieve this is by modifying the crop planting pattern. In this study, we addressed the question to what extent a uniform planting pattern increases the ability of a crop to compete with weed plants for light compared to a random and a row planting pattern, and how this ability relates to crop and weed plant density as well as the relative time of emergence of the weed. To this end, we adopted the functional-structural plant modelling approach which allowed us to explicitly include the 3D spatial configuration of the crop-weed canopy and to simulate intra- and interspecific competition between individual plants for light. Based on results of simulated leaf area development, canopy photosynthesis and biomass growth of the crop, we conclude that differences between planting pattern were small, particularly if compared to the effects of relative time of emergence of the weed, weed density and crop density. Nevertheless, analysis of simulated weed biomass demonstrated that a uniform planting of the crop improved the weed-suppression ability of the crop canopy. Differences in weed suppressiveness between planting patterns were largest with weed emergence before crop emergence, when the suppressive effect of the crop was only marginal. With simultaneous emergence a uniform planting pattern was 8 and 15 % more competitive than a row and a random planting pattern, respectively. When weed emergence occurred after crop emergence, differences between crop planting patterns further decreased as crop canopy closure was reached early on regardless of planting pattern. We furthermore conclude that our modelling approach provides promising avenues to further explore crop-weed interactions and aid in the design of crop management strategies that aim at improving crop competitiveness with weeds.

  13. Circadian response of annual weeds to glyphosate and glufosinate.

    Science.gov (United States)

    Martinson, Krishona B; Sothern, Robert B; Koukkari, Willard L; Durgan, Beverly R; Gunsolus, Jeffrey L

    2002-03-01

    Five field experiments were conducted in 1998 and 1999 in Minnesota to examine the influence of time of day efficacy of glyphosate [N-(phosphonomethyl)glycine] and glufosinate [2-amino-4-(hydroxymethyl-phosphinyl)butanoic acid] applications on the control of annual weeds. Each experiment was designed to be a randomized complete block with four replications using plot sizes of 3 x 9 m. Glyphosate and glufosinate were applied at rates of 0.421 kg ae/ha and 0.292 kg ai/ha, respectively, with and without an additional adjuvant that consisted of 20% nonionic surfactant and 80% ammonium sulfate. All treatments were applied with water at 94 L/ha. Times of day for the application of herbicide were 06:00h, 09:00h, 12:00h, 15:00h, 18:00h, 21:00h, and 24:00h. Efficacy was evaluated 14 d after application by visual ratings. At 14 d, a circadian response to each herbicide was found, with greatest annual weed control observed with an application occurring between 09:00h and 18:00h and significantly less weed control observed with an application at 06:00h, 21:00h, or 24:00h. The addition of an adjuvant to both herbicides increased overall efficacy, but did not overcome the rhythmic time of day effect. Results of the multiple regression analysis showed that after environmental temperature, time of day was the second most important predictor of percent weed kill. Thus, circadian timing of herbicide application significantly influenced weed control with both glyphosate and glufosinate.

  14. Predicting weed problems in maize cropping by species distribution modelling

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    Bürger, Jana

    2014-02-01

    Full Text Available Increasing maize cultivation and changed cropping practices promote the selection of typical maize weeds that may also profit strongly from climate change. Predicting potential weed problems is of high interest for plant production. Within the project KLIFF, experiments were combined with species distribution modelling for this task in the region of Lower Saxony, Germany. For our study, we modelled ecological and damage niches of nine weed species that are significant and wide spread in maize cropping in a number of European countries. Species distribution models describe the ecological niche of a species, these are the environmental conditions under which a species can maintain a vital population. It is also possible to estimate a damage niche, i.e. the conditions under which a species causes damage in agricultural crops. For this, we combined occurrence data of European national data bases with high resolution climate, soil and land use data. Models were also projected to simulated climate conditions for the time horizon 2070 - 2100 in order to estimate climate change effects. Modelling results indicate favourable conditions for typical maize weed occurrence virtually all over the study region, but only a few species are important in maize cropping. This is in good accordance with the findings of an earlier maize weed monitoring. Reaction to changing climate conditions is species-specific, for some species neutral (E. crus-galli, other species may gain (Polygonum persicaria or loose (Viola arvensis large areas of suitable habitats. All species with damage potential under present conditions will remain important in maize cropping, some more species will gain regional importance (Calystegia sepium, Setara viridis.

  15. Host status of six major weeds to Meloidogyne chitwoodi and Pratylenchus penetrans, including a preliminary field survey concerning other weeds

    NARCIS (Netherlands)

    Kutywayo, V.; Been, T.H.

    2006-01-01

    A glasshouse experiment was carried out to investigate the host status of six important weeds in intensive agricultural cropping systems to Meloidogyne chitwoodi and Pratylenchus penetrans. Senecio vulgaris L., Capsella bursa-pastoris (L.) Medic. and Solanum nigrum L. were hosts of M. chitwoodi with

  16. SIMBIOSIS MICORRIZICA ARBUSCULAR Y ACUMULACIÓN DE ALUMINIO EN Brachiaria decumbens Y Manihot esculenta SIMBIOSE MICORRIZICA ARBUSCULAR E ACUMULAÇÃO DE ALUMÍNIO EM Brachiaria decumbens E Manihot esculenta ARBUSCULAR MYCORRHIZAL SYMBIOSIS AND ACUMULATION OF ALUMINUM Brachiaria decumbens AND Manihot esculenta

    Directory of Open Access Journals (Sweden)

    BEATRIZ ELENA GUERRA S.

    2012-12-01

    Full Text Available Suelos dedicados al monocultivo de Elaeis guineensis Jacq en Puerto Wilches-Santander-Colombia, presentan baja fertilidad, altas saturaciones de aluminio y baja densidad de esporas de hongos micorrizicos. Se evaluó el comportamiento de la simbiosis micorrizica utilizando suelos nativos con micorrizas (MA+ y sin micorrizas (MA-, en Brachiaria decumbens y Manihot esculenta, quienes poseen alta micotrofia y capacidad de retención del ión aluminio. Se consideraron las variables densidad de esporas, porcentaje de colonización micorrizica, biomasa seca y longitud radicular, concentración de aluminio foliar y radicular. Se realizó una (ANOVA de dos vías con un modelo lineal general. Se observaron porcentajes de colonización micorrizica superiores al 70% en B. decumbens en suelos con concentraciones de 0,6 y 1,4 meq/100 g de Aluminio. M. esculenta presento 50 % de simbiosis micorrizica, en todos los tipos de suelo. Se incrementaron las esporas nativas de palma aceitera hasta un 200% en las dos plantas huespéd. Las concentraciones de aluminio a nivel radicular fueron mayores en plantas micorrizadas, mientras que a nivel foliar los valores fueron más bajos.Solos dedicados à monocultura de Elaeis guineensis Jacq em Puerto Wilches-Santander apresentam baixa fertilidade, alta saturação de alumínio e baixa densidade de esporos de fungos micorrízicos. Avaliaram-se o comportamento da simbiose micorrízica usando solos nativos com fungos micorrízicos (MA+ e sem fungos micorrízicos (MA-, na Brachiaria decumbens e Manihot esculenta, plantas com alto grau de micotrofia e capacidade de retenção de íons de alumínio. Considerou-se as variáveis: densidade de esporos, porcentagem de colonização micorrízica, biomassa seca, longo da raiz e concentração de alumínio nas folhas e raízes. Realizou-se uma (ANOVA de duas vias com o modelo linear geral. Observou-se porcentagens de colonização micorrízica acima de 70% na B. decumbens em solos com

  17. Weed control in distress – can all weeds still be controlled with herbicides in future?

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    Drobny, Hans G.

    2016-02-01

    Full Text Available The introduction and availability of highly active and selective herbicides in all important field crops, in the last decades, enabled the simplification and money saving in crop rotations and agronomic measures. This resulted in respective specialized and adapted weed populations, and consequently an increasing selection of resistant populations. Since the introduction of the ALS-inhibitors (starting 1985 and the 4-HPPD-inhibitors (2001, no new MoA-Classes were registered, and there are none in the registration process. Several established herbicides were not registered or re-registered in the EU, or were severely restricted in their application. The cost and the risk to develop and register a new selective herbicide in the EU are hardly justified, in relation to their market potential. The only solution on problem fields, with resistant populations, is to change the agronomic practices, like crop rotation, soil tillage, seeding time, etc., as a precautionary principle also on still „normal“ fields. The different advising institutions have to integrate these aspects into their recommendations, besides the proper herbicide management.

  18. The role of plant-microbiome interactions in weed establishment and control.

    Science.gov (United States)

    Trognitz, Friederike; Hackl, Evelyn; Widhalm, Siegrid; Sessitsch, Angela

    2016-10-01

    The soil microbiome plays an important role in the establishment of weeds and invasive plants. They associate with microorganisms supporting their growth and health. Weed management strategies, like tillage and herbicide treatments, to control weeds generally alter soil structure going alongside with changes in the microbial community. Once a weed population establishes in the field, the plants build up a close relationship with the available microorganisms. Seeds or vegetative organs overwinter in soil and select early in the season their own microbiome before crop plants start to vegetate. Weed and crop plants compete for light, nutrition and water, but may differently interact with soil microorganisms. The development of new sequencing technologies for analyzing soil microbiomes has opened up the possibility for in depth analysis of the interaction between 'undesired' plants and crop plants under different management systems. These findings will help us to understand the functions of microorganisms involved in crop productivity and plant health, weed establishment and weed prevention. Exploitation of the knowledge offers the possibility to search for new biocontrol methods against weeds based on soil and plant-associated microorganisms. This review discusses the recent advances in understanding the functions of microbial communities for weed/invasive plant establishment and shows new ways to use plant-associated microorganisms to control weeds and invasive plants in different land management systems. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. EFFECT OF SOWING DATE AND WEED CONTROL METHOD ON THE GROWTH AND YIELD OF SOYBEAN

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    Nasrin Akter

    2016-06-01

    Full Text Available Sowing date and weed management play a significant role in determining soybean growth, development and seed yield. Results showed that different sowing date and weed control methods had significant effect on relative weed density, weed biomass, weed control efficiency, plant height, dry weight plant-1 and seed yield of soybean. Among the infested weed species in the experimental field the dominant weeds were Lindernia procumbens (44.78%, Echinochloa colonum (26.39% and Cynodon dactylon (16.30%. The results also revealed that early sowing (2 January brought about the highest seed yield (2.17 t ha-1 and sowing delay (1 February resulted in the lowest yield (1.64 t ha-1. Two times hand weeding (20 and 40 DAS controlled the weeds most effectively and led to highest seed yield (2.23 t ha-1 which was statistically similar (2.19 t ha-1 with herbicide application. Combination effect showed that the highest seed yield (2.50 t ha-1 was obtained from 2 January sowing when the crop was weeded by hand at 20 and 40 DAS.

  20. Determining the potential of inedible weed biomass for bio-energy and ethanol production

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    Siripong Premjet

    2013-02-01

    Full Text Available Surveys of indigenous weeds in six provinces located in the low northern part of Thailand were undertaken to determine the potential of weed biomass for bio-energy and bio-ethanol. The results reveal that most of the weed samples had low moisture contents and high lower heating values (LHVs. The LHVs at the highest level, ranging from 17.7 to 18.9 Mg/kg, and at the second highest level, ranging from 16.4 to 17.6 Mg/kg, were obtained from 11 and 31 weed species, respectively. It was found that most of the collected weed samples contained high cellulose and low lignin contents. Additionally, an estimate of the theoretical ethanol yields based on the amount of cellulose and hemicellulose in each weed species indicated that a high ethanol yield resulted from weed biomasses with high cellulose and hemicellulose contents. Among the collected weed species, the highest level of ethanol yield, ranging from 478.9 to 548.5 L/ton (substrate, was achieved from 11 weed species. It was demonstrated that most of the collected weed species tested have the potential for thermal conversion and can be used as substrates for ethanol production.