Annual losses of weed seeds due to predation in organic cereal fields

NARCIS (Netherlands)

Westerman, P.R.; Wes, J.S.; Kropff, M.J.; Werf, van der W.

2003-01-01

1. Post-dispersal seed losses in annual arable weed species are poorly quantified, but may be of significance for natural population control, especially if they can be manipulated. We hypothesized that weed seed predation on the soil surface was significant, so we measured rates in the field to

THE STRUCTURE AND YIELD LEVEL OF SWEET CORN DEPENDING ON THE TYPE OF WINTER CATCH CROPS AND WEED CONTROL METHOD

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Robert Rosa

2014-10-01

Full Text Available Organic manuring is suggested to be necessary in sweet corn cultivation. It is not always possible to use farmyard manure due to economic, production or technical reasons. Catch crops used as green manures can be an alternative source of organic matter. The experiment was carried out in central-east Poland (52°06’N, 22°55’E, in years 2008–2011. The successive effect of winter catch crops (hairy vetch, white clover, winter rye, Italian ryegrass, winter turnip rape and the type of weed control on the growth and yielding of sweet corn was examined. The catch crops were sown in early September, incorporated in early May. The effect of the winter catch crops on yield was compared to the effect of FYM at a rate of 30 t·ha-1 and the control without organic manuring. The sweet corn was grown directly after organic fertilization. Three methods of weed control was used: Hw – hand weeding, twice during the growing period, GCM – herbicide Guardian CompleteMix 664 SE, immediately after sowing the seed corn, Z+T – a mixture of herbicides Zeagran 340 SE + Titus 25 WG, in the 3–4 leaf stage sweet corn. The highest yields of biomass were found for winter rye (35.5 t·ha-1 FM and 7.3 t·ha-1 DM, the most of macroelements accumulated winter turnip rape (480.2 kg N+P+K+Ca+Mg·ha-1. Generally, leguminous catch crops had similar to the FYM and better than non-leguminous catch crops yield-forming effect. The highest yield of marketable ears of sweet corn was obtained after FYM (14.4 t·ha-1 and after hairy vetch catch crop (14.0 t·ha-1. A similar yield-forming effect also had white clover and Italian ryegrass. The most of ears from 1 ha was achieved after white clover catch crop (59.3 tausend, similar after FYM and hairy vetch catch crop. The highest kernel yields were found after FYM (10.7 t·ha-1. The yields of kernel after hairy vetch and white clover catch crops were significantly higher than after non-leguminous catch crops. Z+T weed control

Study on the weediness of winter wheat in a long-term fertilization field experiment.

Science.gov (United States)

Lehoczky, E; Kismányoky, A; Kismányoky, T

2006-01-01

The study was carried out in Keszthely, in the long-term fertilization field experiment in April of 2005. In the experiment we had opportunity to compare the weediness in NPK and NPK + FYM* treatments, and we could study the effect of increasing N dosis on the weeds and winter wheat. The weed survey was made on the 20th of April at the end of tillering. For the weed survey used the Balázs-Ujvárosi method. After that we collected all the weeds from the plots per 1 m2. We counted, measured the fresh and dry matter weight of aerial parts. Winter wheat sampels were taken also from all plots (1 running meter per plot). In the experiment 10 weed species were found, 9 annual: Ambrosia artemisiifolia, Consolida regalis, Galium aparine, Lamiunt amplexicaule, Matricaria inodora, Papaver rhoeas, Stellaria media, Veronica hederifolia, Veronica triphyllos, and 1 perennial: Cirsium arvense. Veronica hederifolia was the dominant species in both fertilized plots, Stellaria media has the second highest weed coverage. The manuring treatments, and the N-dosis has important and significantly effect to the weedeness and the biomass production of winter wheat. On the control plots was the relation of biomass weight of weeds the highest. This relation reduced to the effect of N treatments, wich had an favorable effect on the winter wheat.

The Weeds Response to the Winter Vetch (Vicia villosa and Chicklingpea (Lathyrus sativus Cover Crops under Different Tillage Methods in Corn Fields

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Javad Hamzei

2017-01-01

Full Text Available Introduction: Using cover crops in conservation tillage systems offers many advantages, one of which is weed control through physical and chemical interferences. Most of the benefits of cover crops are well known. They prevent form wind and water erosions, conserve soil moisture by reducing evaporation and increasing infiltration, increase the content of organic matter, increase fertility by recycling nutrients, add nitrogen if they are legumes, and improve soil structure. Proper cover crops can also suppress weed growth by allelopathic activities and light interference. They impact on environmental quality through the protection of surface water and groundwater, as well as eliminating the need for using preemergence herbicides. Either increase or decreases have been reported for crop yields when the crop residues remain on soil surface. No-till system has been reported to increase the presence of certain difficult to control weeds. Therefore, the aim of this study was to investigate the effect of tillage systems and cover crops on weed control and corn yield. Materials and Methods: Experiment was carried out as split plot based on randomized complete block design with three replications at the Bu-Ali Sina University in growing season of 2011. Tillage with moldboard, tillage with chisel (minimum tillage, and no tillage were considered as main plots and two cover crops, winter vetch and chicklingpea, chemical weed control and weed-infest treatment (control were considered as sub-plots. Cover crops were cultivated in late March 2011. In early June 2011, cover crops were harvested and were spread over the soil surface. The Plot size was 22.50 m-2. Five rows were in each plot with 75 cm intervals among rows and 18 cm among seedlings. 2 square were picked in the three central rows of each plot in order to determine the yield and yield components. From each plot three quadrants (1×1 mrandomly were picked and weeds and cover crops was separated. All

Weed infestation of a winter wheat canopy under the conditions of application of different herbicide doses and foliar fertilization

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Piotr Kraska

2012-12-01

Full Text Available The present study was carried out in the years 2006-2008 in the Bezek Experimental Farm (University of Life Sciences in Lublin. A two-factor field experiment was set up according to a randomized block design, in three replications. The experimental field was situated on medium heavy mixed rendzina developed from chalk rock with medium dusty loam granulometric composition. The soil was characterised by neutral pH, a very high content of P (342.1 and K (278.9 along with a very low level of magnesium (16.0 mg × kg-1 of soil and organic carbon (over 3.5%. The aim of this research was to compare the effect of three herbicide doses and two foliar fertilizers applied in a winter wheat canopy on weed infestation. The herbicides Mustang 306 SE 0.4 l × ha-1 and Attribut 70 WG 60 g × ha-1 were applied at full recommended doses as well as at doses reduced to 75% and 50%. Foliar fertilizers Insol 3 (1 1 × ha-1 and FoliCare (20 kg × ha-1 were applied at full recommended doses twice in the growing season BBCH* development stage 23-25* and 33-35*. The control was not treated with the herbicides and foliar fertilizers. The weed infestation level was determined by means of the quantitative gravimetric method at two dates: the first one 6 weeks after herbicide application and the second one - before harvest. The number of weed individuals was counted; species composition and air-dry biomass of aboveground parts were estimated from randomly selected areas of 1 m × 0.25 m at four sites on each plot. Galium aparine and Apera spica-venti plants were sampled for molecular analysis 6 weeks after herbicide application (the treatments with the full herbicide dose, a 50% dose and the control without herbicides. The density of weeds and weed air-dry weight were statistically analysed by means of variance analysis, and the mean values were estimated with Tukey's confidence intervals (p=0.05. It was found that the number of weeds and air-dry weight of weeds in the

Evaluation of yield quality and weed infestation of common valerian (Valeriana officinalis L. in dependence on weed control method and forecrop.

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Cezary Kwiatkowski

2012-12-01

Full Text Available A field experiment involving the cultivation of common valerian was conducted on loess soil in Abramów (Lublin region in the period 2007-2009. Qualitative parameters of herbal raw material obtained from this plant as well as in-crop weed infestation were evaluated depending on the protection method and forecrop. Hand-weeded plots, in which a hand hoe was used, were the control. In the other treatments, weeds were controlled using various herbicides and a mechanical implement (brush weeder. Potato and winter wheat + field pea cover crop were the forecrops for common valerian crops. A hypothesis was made that the use of a brush weeder and herbicides not registered for application in valerian crops would have a positive effect on this plant's productivity and weed infestation in its crops. It was also assumed that the introduction of a cover crop would allow the elimination of differences in the forecrop value of the crop stands in question. The best quantitative and qualitative parameters of common valerian raw material as well as the largest reduction of incrop weed infestation were recorded after the application of the herbicides which were not type approved. The use of the brush weeder in the interrows also had a beneficial effect on productivity of the plant in question, but secondary weed infestation at the end of the growing season of common valerian turned out to be its disadvantage. Traditional crop protection methods used in common valerian crops were less effective in weed infestation reduction and they resulted in lower plant productivity and raw material quality. Potato proved to be a better forecrop for common valerian than winter wheat + field pea; however, this positive effect was not confirmed statistically. The following annual weeds: Chenopodium album, Galinsoga parviflora, Stellaria media, were predominant in the common valerian crop. Traditional weed control methods resulted in the dominance of some dicotyledonous weeds, such

Rolled-crimped winter rye cover effects on hand-weeding times and fruit yield and quality of cucurbits

Science.gov (United States)

Fruit and vegetables produced without pesticides are in demand by some segments of society. However, weeds often are deleterious in such crops, and managing them without herbicides is difficult. Stale seedbeds and rolled-crimped winter rye cover crops are non-chemical methods that may help manage we...

Understanding Lolium rigidum Seeds: The Key to Managing a Problem Weed?

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Kathryn J. Steadman

2012-09-01

Full Text Available The 40 million hectare southern Australian winter cropping region suffers from widespread infestation by Lolium rigidum (commonly known as annual or rigid ryegrass, a Mediterranean species initially introduced as a pasture plant. Along with its high competitiveness within crops, rapid adaptability and widespread resistance to herbicides, the dormancy of its seeds means that L. rigidum is the primary weed in southern Australian agriculture. With the individuals within a L. rigidum population exhibiting varying levels of seed dormancy, germination can be staggered across the crop-growing season, making complete weed removal virtually impossible, and ensuring that the weed seed bank is constantly replenished. By understanding the processes involved in induction and release of dormancy in L. rigidum seeds, it may be possible to develop strategies to more effectively manage this pest without further stretching herbicide resources. This review examines L. rigidum seed dormancy and germination from a weed-management perspective and explains how the seed bank can be depleted by control strategies encompassing all stages in the lifecycle of a seed, from development to germination.

Annual warm-season grasses vary for forage yield, quality, and competitiveness with weeds

Science.gov (United States)

Warm-season annual grasses may be suitable as herbicide-free forage crops. A two-year field study was conducted to determine whether tillage system and nitrogen (N) fertilizer application method influenced crop and weed biomass, water use, water use efficiency (WUE), and forage quality of three war...

Evaluation of special, functional and structural diversity of weeds community in pistachios (Pistacia vera L. orchards of Bardaskan County

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S. Elahi

2016-04-01

Full Text Available To study weed species diversity and community structure in pistachio (Pistacia vera L. orchards in 33 orchards of 12 villages an investigation was conducted in Bardaskan County, Khorasan Razavi Province, Iran during 2008-2009. Weed population sampling was conducted in a w shape method using 1m² quadrate. The results showed that the weeds of pistachio orchards were belonging to 15 families and 44 species. dicotyledons (31 species were more than monocotyledons (13 species. Such as in this community, weed species of C3, C4, annual and perennial were 26, 18, 28 and 13, respectively. The majority of weed species were belonging to the plant families of chenopodiceae (9 species and poaceae (12 species amongst dicotyledons and monocotyledons, respectively. the most important species of monocotyledon annual weeds were including Echinochloa crus-gali, Digitaria sanguinlis, Setaria viridis and perennial weeds were including Cyperus routundus, Cynodon dactylon and convolvulus arvensis. Weed species were grouped in seven clusters for density average, frequency and uniformity (similarity 75 percent whereas in eight clusters for relative density average, relative frequency and relative uniformity (similarity 75 percent. Amplitude changes of Shannon-winter diversity index were between 2.3 and 0.16 and of Simpson dominant index were between 0.97 and 0.17. The difference among indices of biodiversity and dominant clusters were relative to scale and type of management practices.

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…

Weeds occurrence in areas submitted to distinct winter crops Ocorrência de plantas daninhas em áreas submetidas a manejos de inverno

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G. Concenço

2012-12-01

Full Text Available In the Western Region of Brazil, it is usual to have two agricultural harvests in the same cropping season. Usually the first crop is soybean, followed by corn. In areas where corn is not planted due to a delayed harvest of soybean, farmers generally do not use winter crops. For these areas, the planting of winter oilseed crops aiming at the production of bio-fuels is one of the best alternatives; in addition, this would help in reducing the occurrence of weed species at the following summer crop. This study aimed to assessing the weed community in distinct winter crops post soybean crop, in terms of species composition, level of infestation and severity of occurrence. The following treatments were evaluated: agriculture under a no-till system with winter fallow, winter oilseed crops (crambe, radish, rapeseed with no-till agriculture in the summer, and agriculture under a conventional tillage system with winter fallow. Phytosociological evaluations of all treatments were carried out 75 DAE of the oilseed crops, and the diversity indexes of Margalef, Menhinick, Simpson, and Shannon-Weiner were determined. Areas were also grouped by cluster analysis based on UPGMA applied at Jaccard's similarity matrix. Among the treatments with winter coverage, radish was the most efficient crop in suppressing the occurrence of weed species. The area with conventional tillage agriculture and winter fallow allowed for a higher occurrence of troublesome weeds. On the other hand, the area under fallow showed the highest absolute level of infestation. Overall, oilseed crops in the winter contribute to lower levels of infestation by weed species in these areas.Na região Centro-Oeste do Brasil, é usual a obtenção de duas colheitas na mesma safra agrícola. Normalmente o primeiro cultivo é de soja, seguida por milho. Em áreas onde o milho não é cultivado devido à colheita tardia da soja, os produtores normalmente não utilizam culturas ou coberturas no per

Estimating Winter Annual Biomass in the Sonoran and Mojave Deserts with Satellite- and Ground-Based Observations

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Bradley C. Reed

2013-02-01

Full Text Available Winter annual plants in southwestern North America influence fire regimes, provide forage, and help prevent erosion. Exotic annuals may also threaten native species. Monitoring winter annuals is difficult because of their ephemeral nature, making the development of a satellite monitoring tool valuable. We mapped winter annual aboveground biomass in the Desert Southwest from satellite observations, evaluating 18 algorithms using time-series vegetation indices (VI. Field-based biomass estimates were used to calibrate and evaluate each algorithm. Winter annual biomass was best estimated by calculating a base VI across the period of record and subtracting it from the peak VI for each winter season (R2 = 0.92. The normalized difference vegetation index (NDVI derived from 8-day reflectance data provided the best estimate of winter annual biomass. It is important to account for the timing of peak vegetation when relating field-based estimates to satellite VI data, since post-peak field estimates may indicate senescent biomass which is inaccurately represented by VI-based estimates. Images generated from the best-performing algorithm show both spatial and temporal variation in winter annual biomass. Efforts to manage this variable resource would be enhanced by a tool that allows the monitoring of changes in winter annual resources over time.

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...

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

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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

Community structure affects annual grass weed invasion during restoration of a shrub-steppe ecosystem

Science.gov (United States)

Phil S. Allen; Susan E. Meyer

2014-01-01

Ecological restoration of shrub-steppe communities in the western United States is often hampered by invasion of exotic annual grasses during the process. An important question is how to create restored communities that can better resist reinvasion by these weeds. One hypothesis is that communities comprised of species that are functionally similar to the invader will...

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.

Impact of an invasive weed, Parthenium hysterophorus, on a pasture community in south east Queensland, Australia.

Science.gov (United States)

Nguyen, Thi; Bajwa, Ali Ahsan; Belgeri, Amalia; Navie, Sheldon; O'Donnell, Chris; Adkins, Steve

2017-12-01

Parthenium weed is a highly invasive alien species in more than 40 countries around the world. Along with severe negative effects on human and animal health and crop production, it also causes harm to ecosystem functioning by reducing the native plant species biodiversity. However, its impacts on native plant species, especially in pasture communities, are less known. Given parthenium weed causes substantial losses to Australian pastures' productivity, it is crucial to estimate its impact on pasture communities. This study evaluates the impact of parthenium weed upon species diversity in a pasture community at Kilcoy, south east Queensland, Australia. Sub-sites containing three levels of parthenium weed density (i.e. high, low and zero) were chosen to quantify the above- and below-ground plant community structure. Species richness, diversity and evenness were all found to be significantly reduced as the density of parthenium weed increased; an effect was evident even when parthenium weed was present at relatively low densities (i.e. two plants m -2 ). This trend was observed in the summer season as well as in winter season when this annual weed was absent from the above-ground plant community. This demonstrates the strong impact that parthenium weed has upon the community composition and functioning throughout the year. It also shows the long-term impact of parthenium weed on the soil seed bank where it had displaced several native species. So, management options used for parthenium weed should also consider the reduction of parthenium weed seed bank along with controlling its above-ground populations.

Uptake of more important mineral components by common field weeds on loess soils

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Leszek Malicki

2013-12-01

Full Text Available We have determined the contents of N, P, K, Ca, Mg, Na, Fe, Cu, Mn and Zn in winter wheat, spring barley, sugar beets and winter rape, as well as in the most common weed species infesting these crops. It was established that the percentage of mineral components in the dry matter of the majority of weeds is higher than in that of the cultivated plants. The most dangerous weed species competing with plants for the investigated nutrients were: Chenopodium album, Cirsium arvense, Convolvulus arvensis, Polygonum convolvulus, Sonchus arvensis and Stellaria media.

Competitive effects of introduced annual weeds on some native and reclamation species in the Powder River Basin, Wyoming

Energy Technology Data Exchange (ETDEWEB)

Allen, E.B.; Knight, D.H.

1980-01-01

Four experiments were conducted to examine the competitive effects of introduced annual weeds on certain native and reclamation species. The first experiment was initiated by discing three sites in the Powder River Basin, Wyoming, at three distances from introduced weed seed sources. Introduced weed colonization was greatest when a seed source was located nearby. Higher weed cover resulted in reductions of percent cover, density, and richness of the native species. The second experiment was conducted in the greenhouse and was designed to determine if there are changes in response of S. kali and the native grasses Agropyron smithii and Bouteloua gracilis to competition and water regime. Both grass species had lower biomass and higher stomatal resistance when growing in mixed culture with S. kali than in pure culture in the dry regime, but there were no significant differences in the wet regime. In general, the difference in plant response between mixed and pure cultures was more pronounced in the dry than in the wet regime. The third study was a greenhouse experiment on germination and competition of S. kali (a C/sub 4/ species) with native species Lepidium densiflorum (C/sub 3/), Chenopodium pratericola (C/sub 3/), A. smithii (C/sub 3/), and B. gracilis (C/sub 4/) under May, June, and July temperature regimes. Salsola kali germinated equally well in all three regimes, but the other C/sub 4/ species had highest germination in the July regime and the C/sub 3/ species in the May and June regimes. The fourth study was designed to examine the effect of weed colonization on the success of mine reclamation. Little effect was observed, but colonization by introduced annuals was very low. (ERB)

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.

Comparisons of weed community, soil health and economic performance between wheat-maize and garlic-soybean rotation systems under different weed managements

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Mahmud A. Muminov

2018-05-01

Full Text Available This study compared the impacts of different weed managements on weed community, soil health and economic performance between the wheat–maize (WM and garlic–soybean (GS rotations. A total of four treatments (H0T, tillage without herbicide; H0T0, without both herbicide and tillage; HT, both herbicide and tillage; HT0, herbicide without tillage were designed for both rotations. A total of 16 weed species were recorded in the WM rotation, with life forms of 62% for annuals, 12% for annual + perennial and 20% for perennials. While in the GS rotation, there were 17 weed species, with 71% being annuals. When crop rotation changed from WM to GS, the topsoil layer seed bank (0–5 cm decreased by 137%. GS rotation always had higher earthworm densities than that of WM under the same condition. Organic weed control (H0T, H0T0 from both WM and GS added more soil organic matters than the chemical methods (HT and HT0. Economically, up to 69% higher net profit had been achieved in the GS than WM for their organic products. This study provides an ecological basis to guide organic farming practices, especially for weed management in the future.

Effect of crop density on competition by wheat and barley with Agrostemma githago and other weeds

DEFF Research Database (Denmark)

Doll, H.; Holm, U.; Søgaard, B.

1995-01-01

The effect of Agrostemma githago L. and other naturally occurring weeds on biomass production and grain yield was studied in winter wheat and winter barley. Naturally occurring weeds had only a negligible effect on barley, but reduced wheat grain yield by 10% at a quarter of normal crop density....... The interaction between the cereals and A. githago was studied in additive series employing different crop densities. Growth of this weed species was strongly dependent on crop density, which was more important for controlling weed growth than it was for obtaining a normal grain yield. Wheat and especially barley...

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)

Analysis of the Heterogeneity of Weed Infestation in Cereal Stands

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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.

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 ...

Using Winter Annual Cover Crops in a Virginia No-till Cotton Production System

OpenAIRE

Daniel, James B. II

1997-01-01

Cotton (Gossypium hirsutum L.) is a low residue crop, that may not provide sufficient surface residue to reduce erosion and protect the soil. A winter annual cover crop could alleviate erosion between cotton crops. Field experiments were conducted to evaluate selected winter annual cover crops for biomass production, ground cover, and N assimilation. The cover crop treatments were monitored under no-till and conventional tillage systems for the effects on soil moisture, cotton yield and qu...

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

The weed seed bank assessment in two soil depths under various mineral fertilising

Directory of Open Access Journals (Sweden)

Elena Hunková

2011-01-01

Full Text Available The field trial at the experimental station of Slovak Agricultural University in Nitra - Kolíňany (Slovak Republic, maize growing region, Haplic Luvisol and Stagni-Haplic Luvisol in 1997 year was established. Experiments were based on 14 ha area (424 x 432.2 m by long strips method. The impact of different mineral fertilisers on six model crops was observed: winter wheat, spring barley, sunflower, winter oilseed rape, maize and sugar beet. Weed infestation of winter wheat, spring barley, maize and sugar beet as well as weed seed bank composition since 2000 year till 2002 year were detected. Three variants of mineral fertilisation were applied: variant 1 – without fertilisers, variant 2 – N-P-K fertilisation, steady state soil nutrients balance, variant 3 – high doses of N-P-K fertilisers (positive soil nutrients balance. Soil weed seed bank was analysed once per year before crop germination (on February from depths 0–0.05 m and 0.20–0.25 m in five replicates. From the depth 0–0.05 m 26 weed species were found, from the depth 0.20–0.25 m 23 weed species, from late spring group mainly. Chenopodium album, Stellaria media and Amaranthus spp. (77.57 % from intact seeds in total were the most occurred weeds in both depths. The year, depth of soil sampling and fertilisation did not have statistically significant impact on weed seeds number in the soil.

Weed species diversity in organic and integrated farming systems

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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

The Effect of Crop Seed Rate and Post Emergence Herbicide Application on Weed control and grain yield of Wheat

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M. Babaei

2017-08-01

Full Text Available Introduction Interference weed with crop is a major concern for production in croplands particularly where modern agricultural practices such as mechanical weeding and the application of herbicides are limited. At present, the aim of weed management is to keep weed population at an acceptable level rather than to keep crop totally free of weeds. Among the weed control methods, the chemical control is the easiest one of the recent origins, as well the most successful alternative method. Materials and methods Field experiments were conducted at Shoushtar Branch, Islamic Azad University, Iran (32 0 3´ N, 480 50´ E during winters of 2012-2013 in order to evaluate the effect of sulfosulfuron and sulfosulfuron plus metsulfuron-methyl at 30 and 45 g a.i. ha-1, respectively, and wheat seed rate at 180, 200 and 220 kg ha-1 on weed control. Experiments were carry out in a randomized complete block design with a factorial arrangement and four replicates. The plot size was 6 m × 2 m. The soil was a clay loam texture, pH 7.4 and 0.6 % organic matter content. In the experimental site, the 30-year average annual rainfall is 321.4 mm, daily average annual air temperature is minimum and maximum 9.5 °C and 46.3 °C, respectively. Wheat cv. Chamran was planted in the first fortnight of November. Seedbed preparation consisted of moldboard plowing, disking and leveling. A basal fertilizer rate of 125 kg ha-1 N (form of urea (46% N, 75 kg ha-1 P2O5 (diammonium phosphate (18% N; 46% P2O5, and 60 kg K2O ha-1 (sulfate of potash (50% K2O was applied. The whole P and K and half of N were applied at sowing. The remaining half of N was top dressed with the irrigation at the booting stage. Results and Discussion As the crop population brings competition for limited resources with the weeds, we tested different seeding rates to increase crop plant density as a measure to control weeds. The weed population was significantly affected by seed rate. In general, there was an

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

Impact of different soil cultivation on weed species in winter rape (oilseed

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Jan Winkler

2005-01-01

Full Text Available A community of weeds and crops is affected by a number of factors, including, among other things, also tillage. In the years 2000–2002, the composition of weed species in rape stands was evaluated on the fields with the total area of 551 hectares (1 hectar equals to some 2.47 acres. The evaluation was carried out with the application of methodology developed by Kühn (1982. On the fields located in the cadastral area of Olomouc – Holice, which had been cultivated in a traditional manner, 115 relevés were recorded. On the fields in the cadastral area of Bohuňovice, which had been cultivated with the application of reduced tillage, 97 relevés were recorded and evaluated. All of the above fields were subjected to the application of chemical agents reducing the occurrence of weeds. The data thus received were processed by means of multidimensional analysis of ecological data with the application of a RDA method (Redundancy Analysis. In the course of three years, 75 weed species were found on the fields under conventional tillage, on the average, 8.2 species per a relevé, while 66 weed species were found during the same period of time on the fields cultivated by means of reduced tillage, on the average, 8.6 species per a relevé. The application of RDA analysis enabled us to sort out the selected species of weeds (i.e. those the frequency of occurrence of which exceeded 15 % into three groups. The conditions provided by the conventional tillage appeared to be more satisfactory for the weed species included in the first group (Arctium tomentosum, Elytrigia repens, Helianthus tuberosus, Chenopodium album, Lolium perenne and Papaver rhoeas. The species included in the second group, i.e. Alsinula media, Apera spica-venti, Atriplex patula, Bromus sterilis, Capsella bursa-pastoris, Equisetum arvense, Fallopia convolvulus, Myosotis arvensis and Thlaspi arvense., responded to reduced tillage by the increase in cover or by increased frequency of

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%....

Weed control and persistence of two oxyfluorfen formulations in olive groves under non tillage conditions.

Science.gov (United States)

Martínez, M J; Farsaoui, K; de Prado, R

2004-01-01

To obtain profitable yields in olive groves, residual preemergence herbicides are applied in October or November before the winter rains, and before the winter annual weeds germinate. Simazine, one of the herbicides most used for weed control in olive groves, has recently been banned. Oxyfluorfen is presented as a good alternative to simazine in olive fields. Experiments were carried out in 2002 and 2003 to evaluate the behaviour of two oxyfluorfen formulations, 2XL and G4F, at 480 g a.i. ha(-1) for three different soil management systems with three replications (1. bare soil; 2. bare soil and grassed buffer strips, chemically controlled and 3. bare soil and grassed buffer strips with controlled mowing; under non tillage conditions in all three cases). The most important species that survived 2XL and G4F treatments was Sagina apetala ARD. Oxyfluorfen residues were evaluated throughout 158 days after the applications. Three soil samples from each plot were collected, mixed and air dried. The herbicide extractions were made with methanol and the residues were analyzed by HPLC. We found no differences between the two formulations, but results showed that recoveries of oxyfluorfen were higher in plots with chemically controlled buffer grassed strips than in the other soil management types.

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

value of NEE (26 and 23 g C m-2). Regarding the annual balance, significant differences were found in NEE between both treatments. The weed cover treatment showed 1.6 times higher annual net C assimilation (-132 g C m-2) than the weed removal treatment (-83 g C m-2). These results highlight the importance of sustainable management practices in agriculture to strengthen the behavior of cropping systems as C sinks.

Skylarks trade size and energy content in weed seeds to maximize total ingested lipid biomass.

Science.gov (United States)

Gaba, Sabrina; Collas, Claire; Powolny, Thibaut; Bretagnolle, François; Bretagnolle, Vincent

2014-10-01

The trade-off between forage quality and quantity has been particularly studied in herbivore organisms, but much less for seed eating animals, in particular seed-eating birds which constitute the bulk of wintering passerines in European farmlands. The skylark is one of the commonest farmland birds in winter, mainly feeding on seeds. We focus on weed seeds for conservation and management purposes. Weed seeds form the bulk of the diet of skylarks during winter period, and although this is still a matter for discussion, weed seed predation by granivorous has been suggested as an alternative to herbicides used to regulate weed populations in arable crops. Our objectives were to identify whether weed seed traits govern foraging decisions of skylarks, and to characterize key seed traits with respect to size, which is related to searching and handling time, and lipid content, which is essential for migratory birds. We combined a single-offer experiment and a multiple-offer one to test for feeding preferences of the birds by estimating seed intake on weed seed species differing in their seed size and seed lipid content. Our results showed (1) a selective preference for smaller seeds above a threshold of seed size or seed size difference in the pair and, (2) a significant effect of seed lipid biomass suggesting a trade-off between foraging for smaller seeds and selecting seeds rich in lipids. Skylarks foraging decision thus seems to be mainly based on seed size, that is presumably a 'proxy' for weed seed energy content. However, there are clearly many possible combinations of morphological and physiological traits that must play crucial role in the plant-bird interaction such as toxic compound or seed coat. Copyright © 2014 Elsevier B.V. All rights reserved.

Chemical weed control in Spinach (Spiniacia oleracea

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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

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

Effects of amount and timing of nitrogen application and weed density on wild mustard (Sinapis arvensis seed production in winter wheat

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mehdi rastgoo

2009-06-01

Full Text Available In order to study the effects of amount and timing of nitrogen application and weed density on wild mustard (Sinapis arvensis seed production in winter wheat, an experiment was conducted in 2001 at Research station of college of agriculture, Ferdowsi University of Mashhad. A Split plot design with three replications were used with factorial combination of weed density (0, 8, 16, and 32 plant/m2 and nitrogen (low=100, optimum= 150, and high= 225 Kg/ha as main plots.The sub plot factor included nitrogen splitting pattern (P1=1/3 at planting time+2/3 at tillering, P2= 1/3 at planting time + 1/3 at tillering + 1/3 at shooting. According to the results, wild mustard seed production increased with increasing wild mustard density and nitrogen rates, due to high wild mustard biomass production. Seed production of wild mustard was 161, 311, and 488 million/ha in low, optimum and high nitrogen rates, respectively. In the other hand, density and nitrogen rates had a significant effect on wild mustard fecundity. However, nitrogen splitting pattern showed no significant effect on wild mustard seed production.

Effect of Cover Crops and Nitrogen Fertilizer on Total Production of Forage Corn and Dry Weight of Weeds

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R Fakhari

2014-10-01

Full Text Available To evaluate the effect of cover crops, split application of nitrogen and control weeds on forage corn and weed biomass a factorial experiment based on randomized complete block design with three replications and three factors was conducted at the Agricultural Research Station of Ardabil (Iran during 2012 crop year. The first factor was cover crops (consisting of winter rye, hairy vetch, berseem clover, with and without weeding as controls. The second factor was two levels of split application of 225 kg.ha-1 urea at two growth stages forage corn: the first level (N1= 1/2 at planting and 1/2 at 8-10 leaf stage, second level (N2= 1/3 at planting, 1/3 at 8-10 leaf and 1/3 one week before tasselling stage. The third factor consisted of two levels of weed control: weeding at 8 leaves and weeding one week before tasselling. Results showed that winter rye, hairy vetch and berseem clover cover crops decreased total weed dry weights up to 87, 82 and 65 % respectively as compared to control (without weeding. Cover crops and nitrogen application time had a significant effect on yield of fresh forage corn and cover crops. Based on the advantages of effective weed control and higher forage production of hairy vetch it can be recommended as proper cover crop.

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...

Soil physical attributes in forms of sowing the annual winter pasture and intervals between grazing

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Milton da Veiga

Full Text Available The sowing of winter pastures in areas used for summer grain production and their management under direct cattle grazing can cause changes in soil physical attributes, whose intensity depends on the degree of soil mobilization, grazing interval, stocking rate and weather. To study these aspects it was conducted over four years an experiment in a randomized block with split plots design and four replications. In the main plots were applied two forms of sowing the annual winter pasture (direct seeding and seeding + harrowing and, in the subplots, four intervals between grazing (7, 14 and 28 days and ungrazed. Undisturbed soil cores were sampled at the end of each grazing cycle, in the 0-0.05 m layer to determine the saturated hydraulic conductivity and aggregate stability and in the layers of 0-0.05, 0.05-0.10, 0.10-0.15 and 0.15-0.20 m depth to determine bulk density and classes of soil pores. The direct seeding of annual winter pasture increases hydraulic conductivity and reduces soil bulk density in relation to seeding + harrowing while dairy cows trampling increases soil density and reduces macroporosity in the most superficial soil layer. The variation in climatic conditions among grazing cycles affects the soil physical attributes more markedly than forms of sowing and intervals between grazing of the annual winter pasture.

Leaf anatomical and photosynthetic acclimation to cool temperature and high light in two winter versus two summer annuals.

Science.gov (United States)

Cohu, Christopher M; Muller, Onno; Adams, William W; Demmig-Adams, Barbara

2014-09-01

Acclimation of foliar features to cool temperature and high light was characterized in winter (Spinacia oleracea L. cv. Giant Nobel; Arabidopsis thaliana (L.) Heynhold Col-0 and ecotypes from Sweden and Italy) versus summer (Helianthus annuus L. cv. Soraya; Cucurbita pepo L. cv. Italian Zucchini Romanesco) annuals. Significant relationships existed among leaf dry mass per area, photosynthesis, leaf thickness and palisade mesophyll thickness. While the acclimatory response of the summer annuals to cool temperature and/or high light levels was limited, the winter annuals increased the number of palisade cell layers, ranging from two layers under moderate light and warm temperature to between four and five layers under cool temperature and high light. A significant relationship was also found between palisade tissue thickness and either cross-sectional area or number of phloem cells (each normalized by vein density) in minor veins among all four species and growth regimes. The two winter annuals, but not the summer annuals, thus exhibited acclimatory adjustments of minor vein phloem to cool temperature and/or high light, with more numerous and larger phloem cells and a higher maximal photosynthesis rate. The upregulation of photosynthesis in winter annuals in response to low growth temperature may thus depend on not only (1) a greater volume of photosynthesizing palisade tissue but also (2) leaf veins containing additional phloem cells and presumably capable of exporting a greater volume of sugars from the leaves to the rest of the plant. © 2014 Scandinavian Plant Physiology Society.

Competition between crops and weeds in the Zanderij area of Suriname

NARCIS (Netherlands)

Everaarts, A.P.

1991-01-01

A weed flora rapidly built up with the cultivation of annual crops on two experimental farms in the Zanderij area of Suriname, despite the fact that the farms were newly established in forested areas. Studies indicated that without adequate weed control, significant yield losses occurred in

Applying Neural Networks to Hyperspectral and Multispectral Field Data for Discrimination of Cruciferous Weeds in Winter Crops

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Ana-Isabel de Castro

2012-01-01

Full Text Available In the context of detection of weeds in crops for site-specific weed control, on-ground spectral reflectance measurements are the first step to determine the potential of remote spectral data to classify weeds and crops. Field studies were conducted for four years at different locations in Spain. We aimed to distinguish cruciferous weeds in wheat and broad bean crops, using hyperspectral and multispectral readings in the visible and near-infrared spectrum. To identify differences in reflectance between cruciferous weeds, we applied three classification methods: stepwise discriminant (STEPDISC analysis and two neural networks, specifically, multilayer perceptron (MLP and radial basis function (RBF. Hyperspectral and multispectral signatures of cruciferous weeds, and wheat and broad bean crops can be classified using STEPDISC analysis, and MLP and RBF neural networks with different success, being the MLP model the most accurate with 100%, or higher than 98.1%, of classification performance for all the years. Classification accuracy from hyperspectral signatures was similar to that from multispectral and spectral indices, suggesting that little advantage would be obtained by using more expensive airborne hyperspectral imagery. Therefore, for next investigations, we recommend using multispectral remote imagery to explore whether they can potentially discriminate these weeds and crops.

Allelopatic potential of weeds under the minimalization of soil treatment

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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.

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....

Clearfield®-Clentiga® and Clearfield® Kombi-Pack: Two new herbicides for targeted weed control in winter- and spring oilseed rape

Directory of Open Access Journals (Sweden)

Schönhammer, Alfons

2014-02-01

Full Text Available Currently, the Clearfield® Production System in winter oilseed rape in Germany is based on the herbicide Clearfield®-Vantiga® , a combination product consisting of the active ingredients metazachlor, quinmerac and imazamox, sold as Clearfield-Vantiga D together with the adjuvant Dash® E.C.. Clearfield-Vantiga D was introduced in autumn 2012 and has since proved superior performance on more than 10 000 ha of heavily weedy fields due to the very broad spectrum of activity, reliable foliar and soil activity and excellent crop safety in Clearfield oilseed rape hybrids. Although the authorized application period is very long (BBCH 10-18, it is mostly used relatively early, as soon as the majority of the important weeds is emerged. Metazachlor which is active mainly by cotyledon, hypocotyl and root uptake, is favoured by early applications. Clearfield-Clentiga is a suspension concentrate (SC, consisting of 250 g/l quinmerac and 12.5 g/l imazamox . The application rate is 1.0 l/ha + 1.0 l/ha of the adjuvant Dash E.C.. Approval is sought for use in winter oilseed rape in autumn (BBCH 10-18 and spring (BBCH 30-50 and in spring oilseed rape (BBCH 10-18. Results are presented for the autumn application in winter oilseed rape. A prerequisite for the application of both Clearfield-Clentiga and Clearfield-Vantiga D is the use of imazamox tolerant oilseed rape (Clearfield varieties. The amounts of active ingredient per hectare of quinmerac and imazamox are identical in Clearfield-Clentiga and Clearfield-Vantiga D, as well as the amount of adjuvant Dash E.C.. Clearfield-Clentiga, as a consequence of the absence of metazachlor, compared to Clearfield-Vantiga D has a slightly more limited spectrum of activity and a less pronounced soil activity, but provides greater flexibility in the choice of the application dates and of combinations with soil and foliar herbicides. Very effective, even at high weed pressure and in difficult soil conditions, are sequential

Exploitation of allelopathy for weed control in annual and perennial cropping systems.

Science.gov (United States)

Putnam, A R; Defrank, J; Barnes, J P

1983-08-01

A variety of crops, cultivars, and accessions have been evaluated over the past six years for superior capability to suppress weed growth. The most successful of these approaches has been to grow cover crops of rye (Secale cereale), wheat (Triticum aestivum), sorghum (Sorghum bicolor), or barley (Hordeum vulgare) to a height of 40-50 cm, desiccate the crops by contact herbicides or freezing, and allow their residues to remain on the soil surface. Often, up to 95% control of important agroecosystem weed species was obtained for a 30- to 60-day period following desiccation of the cover crop. The plant residues on the soil surface exhibit numerous physical and chemical attributes that contribute to weed suppression. Physical aspects include shading and reduced soil temperatures which were similarly achieved using poplar (Populus) excelsior as a control mulch. Chemical aspects apparently include direct release of toxins, as well as production of phytotoxic microbial products. Numerous chemicals appear to work in concert or in an additive or synergistic manner to reduce weed germination and growth.

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...

Paired comparison of water, energy and carbon exchanges over two young maritime pine stands (Pinus pinaster Ait.): effects of thinning and weeding in the early stage of tree growth.

Science.gov (United States)

Moreaux, Virginie; Lamaud, Eric; Bosc, Alexandre; Bonnefond, Jean-Marc; Medlyn, Belinda E; Loustau, Denis

2011-09-01

The effects of management practices on energy, water and carbon exchanges were investigated in a young pine plantation in south-west France. In 2009-10, carbon dioxide (CO(2)), H(2)O and heat fluxes were monitored using the eddy covariance and sap flow techniques in a control plot (C) with a developed gorse layer, and an adjacent plot that was mechanically weeded and thinned (W). Despite large differences in the total leaf area index and canopy structure, the annual net radiation absorbed was only 4% lower in plot W. We showed that higher albedo in this plot was offset by lower emitted long-wave radiation. Annual evapotranspiration (ET) from plot W was 15% lower, due to lower rainfall interception and transpiration by the tree canopy, partly counterbalanced by the larger evaporation from both soil and regrowing weedy vegetation. The drainage belowground from plot W was larger by 113 mm annually. The seasonal variability of ET was driven by the dynamics of the soil and weed layers, which was more severely affected by drought in plot C. Conversely, the temporal changes in pine transpiration and stem diameter growth were synchronous between sites despite higher soil water content in the weeded plot. At the annual scale, both plots were carbon sinks, but thinning and weeding reduced the carbon uptake by 73%: annual carbon uptake was 243 and 65 g C m(-2) on plots C and W, respectively. Summer drought dramatically impacted the net ecosystem exchange: plot C became a carbon source as the gross primary production (GPP) severely decreased. However, plot W remained a carbon sink during drought, as a result of decreases in both GPP and ecosystem respiration (R(E)). In winter, both plots were carbon sources, plots C and W emitting 67.5 and 32.4 g C m(-2), respectively. Overall, this study highlighted the significant contribution of the gorse layer to mass and energy exchange in young pine plantations.

Increasing weed flora in Danish beet, pea and winter barley fields

DEFF Research Database (Denmark)

Andreasen, Christian; Stryhn, Henrik

2012-01-01

.g. Capsella bursa-pastoris (L.) Medik, Cirsium arvense (L. Scop.), Galium aparine L., Fallopia convolvulus (L.) Á. Löwe, Tripleurospermum inodorum (L.) Sch. Bip.) have been favoured. Some weeds have declined in some crops but increased in other crops (e.g. Chenopodium album L., Geranium pusillum L.), while...

[Diversity and classification system of weed community in Harbin City, China].

Science.gov (United States)

Chen, Xiao-Shuang; Liang, Hong; Song, Kun; Da, Liang-Jun

2014-08-01

To analyze the causes of weed community diversity and their strategies of adaption to the high heterogeneity of urban habitats, weed communities in the central urban area of Harbin, China were studied, and a classification system was established for the weed communities. There were 175 weed species, belonging to 128 genera and 38 families. The heterogeneous urban habitats and species' temporal niche differentiation resulted in the highly diversified weed communities. The high proportions of mono-species dominance and annual species dominance communities were their response to the unstable urban habitats under human disturbances with high intensities and frequencies. A four-level classification system was established in terms of plant species and habitat conditions. Within this system, the identified 1763 weed communities could be categorized into two types of life form, 5 types of dormancy form, 22 community groups, and 119 dominance communities.

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

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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%.

Effect of Cover Crops on Vertical Distribution of Leaf Area and Dry Matter of Soybean (Glycine max L. in Competition with Weeds

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seyyedeh samaneh hashemi

2017-08-01

Full Text Available Introduction Amount and vertical distribution of leaf area are essential for estimating interception and utilization of solar radiation of crop canopies and, consequently dry matter accumulation (Valentinuz & Tollenaar, 2006. Vertical distribution of leaf area is leaf areas per horizontal layers, based on height (Boedhram et al., 2001. Above-ground biomass is one of the central traits in functional plant ecology and growth analysis. It is a key parameter in many allometric relationships (Niklas & Enquist, 2002. The vertical biomass distribution is considered to be the main determinant of competitive strength in plant species. The presence of weeds intensifies competition for light, with the effect being determined by plant height, position of the branches, and location of the maximum leaf area. So, this experiment was conducted to study the vertical distribution of leaf area and dry matter of soybean canopy in competition with weeds and cover crops. Materials and methods This experiment was performed based on complete randomized block design with 3 replications in center of Agriculture of Joybar in 2013. Soybean was considered as main crop and soybean and Persian clover (Trifolium resupinatum L., fenugreek (Trigonella foenum–graecum L., chickling pea (Lathyrus sativus L. and winter vetch (Vicia sativa L. were the cover crops. Treatments were included cover crops (Persian clover, fenugreek, chickling pea and winter vetch and cover crop planting times (simultaneous planting of soybean with cover crops and planting cover crops three weeks after planting of soybeans and also monoculture of soybeans both in weedy and weed free conditions were considered as controls. Soybean planted in 50 cm row spacing with 5 cm between plants in the same row. Each plot was included 5 rows soybeans. Cover crop inter-seeded simultaneously in the main crop. Crops were planted on 19 May 2013 for simultaneous planting of soybean. The dominant weed species were green

Weed interference with peppermint (Mentha x piperita L.) and spearmint (Mentha spicata L.) crops under different herbicide treatments: effects on biomass and essential oil yield.

Science.gov (United States)

Karkanis, Anestis; Lykas, Christos; Liava, Vasiliki; Bezou, Anna; Petropoulos, Spyridon; Tsiropoulos, Nikolaos

2018-01-01

'Minor crops' such as spearmint and peppermint are high added value crops, despite the fact that their production area is comparably small worldwide. The main limiting factor in mint commercial cultivation is weed competition. Thus, field experiments were carried out to evaluate the effects of weed interference on growth, biomass and essential oil yield in peppermint and spearmint under different herbicide treatments. The application of pendimethalin and oxyfluorfen provided better control of annual weeds resulting in higher crop yield. Additionally, when treated with herbicides both crops were more competitive against annual weeds in the second year than in the first year. All pre-emergence herbicides increased biomass yield, since pendimethalin, linuron and oxyfluorfen reduced the density of annual weeds by 71-92%, 63-74% and 86-95%, respectively. Weed interference and herbicide application had no effect on essential oil content; however, a relatively strong impact on essential oil production per cultivated area unit was observed, mainly due to the adverse effect of weed interference on plant growth. Considering that pendimethalin and oxyfluorfen were effective against annual weeds in both spearmint and peppermint crops, these herbicides should be included in integrated weed management systems for better weed management in mint crops. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Interspecific variation in persistence of buried weed seeds follows trade-offs among physiological, chemical, and physical seed defenses.

Science.gov (United States)

Davis, Adam S; Fu, Xianhui; Schutte, Brian J; Berhow, Mark A; Dalling, James W

2016-10-01

Soil seedbanks drive infestations of annual weeds, yet weed management focuses largely on seedling mortality. As weed seedbanks increasingly become reservoirs of herbicide resistance, species-specific seedbank management approaches will be essential to weed control. However, the development of seedbank management strategies can only develop from an understanding of how seed traits affect persistence.We quantified interspecific trade-offs among physiological, chemical, and physical traits of weed seeds and their persistence in the soil seedbank in a common garden study. Seeds of 11 annual weed species were buried in Savoy, IL, from 2007 through 2012. Seedling recruitment was measured weekly and seed viability measured annually. Seed physiological (dormancy), chemical (phenolic compound diversity and concentration; invertebrate toxicity), and physical traits (seed coat mass, thickness, and rupture resistance) were measured.Seed half-life in the soil ( t 0.5 ) showed strong interspecific variation ( F 10,30  = 15, p  central role of seed dormancy in controlling seed persistence.A quantitative comparison between our results and other published work indicated that weed seed dormancy and seedbank persistence are linked across diverse environments and agroecosystems. Moreover, among seedbank-forming early successional plant species, relative investment in chemical and physical seed defense varies with seedbank persistence. Synthesis and applications . Strong covariance among weed seed traits and persistence in the soil seedbank indicates potential for seedbank management practices tailored to specific weed species. In particular, species with high t 0.5 values tend to invest less in chemical defenses. This makes them highly vulnerable to physical harvest weed seed control strategies, with small amounts of damage resulting in their full decay.

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

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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.

Efeito de coberturas de inverno e sua época de manejo sobre a infestação de plantas daninhas na cultura de milho Effect of winter cover crops and their management timing on weed infestation in maize crop

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A.A. Balbinot Jr.

2007-09-01

Full Text Available No sistema de plantio direto, a presença de palha sobre o solo proporciona significativa supressão de plantas daninhas. O objetivo deste trabalho foi avaliar o potencial de coberturas de inverno e sua época de manejo em reduzir a infestação de plantas daninhas na cultura de milho quando semeada em sucessão. Dois experimentos foram realizados em Canoinhas, SC, nas safras 2003/04 e 2004/05. No primeiro experimento, avaliaram-se seis coberturas de solo no inverno: nabo forrageiro, aveia-preta, centeio, azevém, consórcio entre aveia-preta e ervilhaca e o consórcio entre nabo forrageiro, aveia-preta, centeio, azevém e ervilhaca. Essas coberturas foram roçadas em três épocas antes da semeadura do milho: 1, 10 e 25 dias. Já no segundo experimento, foram avaliados os efeitos de supressão de plantas daninhas pela palha das seis coberturas citadas anteriormente, mais a ervilhaca. As palhas de azevém e do consórcio das cinco espécies utilizadas no experimento apresentaram alta capacidade em suprimir a emergência e o acúmulo de massa seca das plantas daninhas, enquanto a palha de nabo forrageiro apresentou baixo potencial de supressão. O manejo das coberturas próximo à semeadura da cultura de milho reduziu a infestação de plantas daninhas.Straw on the soil significantly reduces weed infestation under the no-tillage system. The aim of this research was to evaluate the potential of winter cover crops and their management timing in reducing weed infestation in maize crop. Two experiments were carried out in Canoinhas, SC, Brazil, in 2003/2004 and 2004/2005. In the first experiment, six winter cover crops were investigated: oilseed radish, black oat, rye, rye grass, intercropped among black oat and common vetch and among oilseed radish, black oat, rye, ryegrass and common vetch. These cover crops were slashed down at three different times before maize seeding (1, 10 and 25 days. In the second experiment, the potential to reduce weed

The diversity of weed species occurring in living mulch in an apple orchard

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Maria Licznar-Małańczuk

2014-04-01

Full Text Available In a study conducted at the Research Station of the Wrocław University of Environmental and Life Sciences, weed occurrence in living mulches maintained in apple tree rows of ‘Pinova’ cv. was assessed during the first seven years after sowing. The trees were planted in spring 2004 (3.5 × 1.2 m. In the same year, living mulches: colonial bent grass, white clover and French marigold, were sown into 1 m wide tree rows. Blue fescue, the only perennial cover crop with herbicide application against dicot weeds once in the second year after sowing, was introduced in the second year after planting the trees to replace dwarf nasturtium which was sown in the year of orchard establishment. In the inter-row spaces, perennial grass was maintained. During the first seven years, variation in weeds was observed depending on living mulch. Multi-species weed infestation persisted throughout the study period only in the case of annually resown French marigold. Perennial living mulches were significantly suppressed the annual weeds. Significant suppression of Taraxacum officinale Web. was found where the soil surface was covered by perennial grass sod in more than ¾. The maintenance of blue fescue resulted in significantly lower average soil coverage by Elymus repens (L. Gould; the growth of this weed significantly contributed to the reduction of white clover sod and French marigold plants.

Herbicide spring treatments for the control of brome grasses (Bromus spp. in winter cereals

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Gehring, Klaus

2014-02-01

Full Text Available The efficacy of different ALS-inhibiting herbicides for the control of brome species (Bromus spp. was tested in three field trials in the year 2010 – 2012 in the region of North-West-Bavaria Franken. As a result of the trials the standard herbicide Attribut (Propoxycarbazone was confirmed for the control of brome. In case of infestation with brome and black grass the herbicide Broadway (Pyroxsulam offers a certain control of both problematic grass weeds. This illustrates the high dependency of sufficient brome control in winter cereals on the effectiveness of specific ALS-Inhibitor herbicides. Because of the high risk of herbicide resistance to ACCaseand ALS-inhibiting herbicides in brome, integrated weed management is essential for the sustainable control of brome in winter cereals, respectively winter wheat.

Weeds and Wildlife: Perceptions and Practices of Weed Managers

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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.

Annual glyphosate treatments alter growth of unaffected bentgrass (Agrostis weeds and plant community composition.

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Collin W Ahrens

Full Text Available Herbicide resistance is becoming more common in weed ecotypes and crop species including turfgrasses, but current gaps in knowledge limit predictive ecological risk assessments and risk management plans. This project examined the effect of annual glyphosate applications on the vegetative growth and reproductive potential of two weedy bentgrasses, creeping bentgrass (CB and redtop (RT, where the glyphosate resistance (GR trait was mimicked by covering the bentgrass plants during glyphosate application. Five field plots were studied in habitats commonly inhabited by weedy bentgrasses including an agricultural hayfield, natural meadow, and wasteland. Results showed that annual glyphosate treatment improved bentgrass survivorship, vegetative growth, and reproductive potential compared with bentgrass in unsprayed subplots. In the second year of growth, RT plants had an 86-fold increase in flower number in glyphosate-treated subplots versus controls, while CB plants had a 20-fold increase. At the end of the three year study, plant community composition had changed in glyphosate-treated subplots in hayfield and meadow plots compared to controls. Soils in subplots receiving glyphosate had higher nitrate concentrations than controls. This is the first study to mimic the GR trait in bentgrass plants with the goal of quantifying bentgrass response to glyphosate selection pressure and understanding the impacts on surrounding plant communities.

Impact of fertilizing pattern on the biodiversity of a weed community and wheat growth.

Science.gov (United States)

Tang, Leilei; Cheng, Chuanpeng; Wan, Kaiyuan; Li, Ruhai; Wang, Daozhong; Tao, Yong; Pan, Junfeng; Xie, Juan; Chen, Fang

2014-01-01

Weeding and fertilization are important farming practices. Integrated weed management should protect or improve the biodiversity of farmland weed communities for a better ecological environment with not only increased crop yield, but also reduced use of herbicides. This study hypothesized that appropriate fertilization would benefit both crop growth and the biodiversity of farmland weed communities. To study the effects of different fertilizing patterns on the biodiversity of a farmland weed community and their adaptive mechanisms, indices of species diversity and responses of weed species and wheat were investigated in a 17-year field trial with a winter wheat-soybean rotation. This long term field trial includes six fertilizing treatments with different N, P and K application rates. The results indicated that wheat and the four prevalent weed species (Galium aparine, Vicia sativa, Veronica persica and Geranium carolinianum) showed different responses to fertilizer treatment in terms of density, plant height, shoot biomass, and nutrient accumulations. Each individual weed population exhibited its own adaptive mechanisms, such as increased internode length for growth advantages and increased light interception. The PK treatment had higher density, shoot biomass, Shannon-Wiener and Pielou Indices of weed community than N plus P fertilizer treatments. The N1/2PK treatment showed the same weed species number as the PK treatment. It also showed higher Shannon-Wiener and Pielou Indices of the weed community, although it had a lower wheat yield than the NPK treatment. The negative effects of the N1/2PK treatment on wheat yield could be balanced by the simultaneous positive effects on weed communities, which are intermediate in terms of the effects on wheat and weeds.

Effect of Time and Burial Depth on Breaking Seed dormancy and Germination of Weed Seeds

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marzie mazhari

2016-02-01

Full Text Available Introduction: Weeds limit crop growth, development and yield through competing. Seed bank of weeds in field is one of the sources which can affect weed management and their control methods. Environmental conditions during seed maturation and following dispersal interact to influence the germination phenology of many species. Disturbance plays a key role in the maintenance of habitat for many plant species, particularly referrals, for example, fire ephemerals, desert annuals, and arable weeds. Seed germination and emergence depend on endogenous and exogenous factors. Viable seeds are dormant when all environmental conditions are appropriate for germination but seeds fail to germinate. Thus, dormancy plays an important ecological role in preventing seed germination, being a major contributor to seed persistence of some species in soil. Buried seeds of annual weeds are certainly subjected to different soil moisture conditions during their dormancy release season (winter according to the annual rainfall pattern and burial depth. Shallow buried seeds are exposed to soil moisture fluctuations that could affect their dormancy status. Laboratory studies showed that desiccation and subsequent re-hydration of seeds could stimulate germination and modify seed light requirements. Seeds buried in deeper layers of the soil would not be exposed to such fluctuations in soil moisture, but would be exposed to different soil moisture environments depending on weather and soil characteristics. The effects of interactions between temperature, and soil or seed moisture, on seed dormancy changes have been reported for several species. Therefore, the objectives of this study were to determine the effect of time and burial depth treatments on seed germination and seedling emergence of Aegilops cylindrica, Agropyrom repens, Avena fatua, Bromus dantoniae, Cynodon dactylon, Cyprus rotundus, Setaria viridis, Anthriscus sylvestris, Centurea cyanus. Materials and Methods: In

Mechanical pre-planting weed control in short rotation coppice using deep forestry ploughing techniques

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

This report describes a trial by Border biofuels to investigate the deep forestry plough as a mechanical pre-planting weed control method to reduce weed infestations in willow coppice and thus contribute to improved establishment and eventual yield. The results suggest that there was a considerable increase in biomass productivity from the deep ploughed area compared to the conventionally cultivated area at all three SRC sites tested. This technique also suggests that the deep forestry ploughing provides the benefit of much reduced levels of seed germination of many annual weed species and a reduction in levels of perennial weed infestation. It is not possible at this stage to predict the longer term benefits in terms of harvestable biomass productivity but it may be considered that the improved establishment and lack of weed competition would consistently produce higher yields of biomass than plantations which suffer from persistent and invasive weed competition. (author)

Effects of Corn Canopy on Seedling Emergence of Seven Weed Species

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F Kordbacheh

2012-02-01

Full Text Available In this research corn were planted in 3 densities (8, 12, 16 plant/m2 in two planting patterns (single and double-row with seven summer weed species, including redroot pigweed, green foxtail, annual bluegrass, common lambsquarter, jimsonweed, black nightshade and johnsongrass were planted. Temperature, quality and quantity of light reaching to soil surface were measured and the number of emerged seedlings for each weed species was countered in three sampling dates. Temperature fluctuation wasn't affected by density and planting patterns and was reduced with canopy formation. In all weed species 3 seedling emergence patterns were observed. In small seed species, redroot pigweed had one germination flush, so it was not respond to crop canopy. The number of emerged weed seedlings of annual bluegrass, common lambsquarter and green foxtail were significantly higher in bareground than under corn canopy. In double-row planting pattern was higher compared to the single-row and had three germination flushes. The number of emerged seedlings in the species with relatively large seeds had no significant difference between bareground and under corn canopy in jimsonweed and black nightshade. But it increased in johnsongrass under corn canopy compare to the bare ground. In all three species it was higher in double-row compare to single-row pattern. Jimsonweed had three germination flushes but blacknightshade and johnsongrass had 1 germination flush.

The weed composition in an orchard as a result of long-term foliar herbicide application

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Maria Licznar-Małańczuk

2016-09-01

Full Text Available The weed composition and the dominance of individual species occurring in an orchard were assessed at the Research Station of the Wrocław University of Environmental and Life Sciences, Poland, during the first 10 years after orchard establishment. ‘Ligol’ apple trees were planted in the spring of 2004 (3.5 × 1.2 m. Foliar herbicides were applied in 1 m wide tree rows twice or three times per each vegetation period. In the inter-row spaces, perennial grass was maintained. Ten years of maintenance of herbicide fallow contributed to a change in the weed composition in the orchard. It changed as a result of different responses of the most important weed species to the foliar herbicides. Total suppression of Elymus repens was observed in the first year after planting the trees. Convolvulus arvensis, Cirsium arvense, and other perennial weeds, completely disappeared in the succeeding periods. The maintenance of herbicide fallow did not affect the abundance of Taraxacum officinale. The percentage of the soil surface covered by Trifolium repens and Epilobium adenocaulon, perennial weeds with considerable tolerance to post-emergence herbicides, increased during the fruit-bearing period of the trees. The abundance of these weeds was significantly reduced only in the rows with the stronger growing trees on the semi-dwarf P 2 rootstock. Stellaria media was the dominant annual weed. Senecio vulgaris, Poa annua, Capsella bursa-pastoris, and Lamium spp. were also frequently observed. A significant increase in the abundance of annual and perennial weeds was found in the tree rows as a result of improved water availability after a period of high precipitation.

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....

Hellsgate Big Game Winter Range Wildlife Mitigation Project : Annual Report 2008.

Energy Technology Data Exchange (ETDEWEB)

Whitney, Richard P.; Berger, Matthew T.; Rushing, Samuel; Peone, Cory

2009-01-01

The Hellsgate Big Game Winter Range Wildlife Mitigation Project (Hellsgate Project) was proposed by the Confederated Tribes of the Colville Reservation (CTCR) as partial mitigation for hydropower's share of the wildlife losses resulting from Chief Joseph and Grand Coulee Dams. At present, the Hellsgate Project protects and manages 57,418 acres (approximately 90 miles2) for the biological requirements of managed wildlife species; most are located on or near the Columbia River (Lake Rufus Woods and Lake Roosevelt) and surrounded by Tribal land. To date we have acquired about 34,597 habitat units (HUs) towards a total 35,819 HUs lost from original inundation due to hydropower development. In addition to the remaining 1,237 HUs left unmitigated, 600 HUs from the Washington Department of Fish and Wildlife that were traded to the Colville Tribes and 10 secure nesting islands are also yet to be mitigated. This annual report for 2008 describes the management activities of the Hellsgate Big Game Winter Range Wildlife Mitigation Project (Hellsgate Project) during the past year.

Atlantis FLEX (BAY 22010 H – a new herbicide in cereals with efficacy against grasses

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Kerlen, Dirk

2014-02-01

Full Text Available Atlantis FLEX (Mesosulfuron-methyl; Propoxycarbazone-sodium; Mefenpyr-diethyl is a new cereal herbicide to control blackgrass (Alopecurus myosuroides, ryegrass (Lolium spec., brome grass (Bromus spec., wild oat (Avena fatua, loose silky-bentgrass (Apera spica-venti L, annual meadow-grass (Poa annua L. and dicot weeds. Atlantis FLEX can be used in winter wheat, winter triticale, winter rye, winter durum wheat and spelt. The publication is based on efficacy trials from two years of spring application with Atlantis FLEX. It will be shown, that Atlantis FLEX generates a good to excellent efficacy against grass-weeds.

Estimating inter-annual variability in winter wheat sowing dates from satellite time series in Camargue, France

Science.gov (United States)

Manfron, Giacinto; Delmotte, Sylvestre; Busetto, Lorenzo; Hossard, Laure; Ranghetti, Luigi; Brivio, Pietro Alessandro; Boschetti, Mirco

2017-05-01

Crop simulation models are commonly used to forecast the performance of cropping systems under different hypotheses of change. Their use on a regional scale is generally constrained, however, by a lack of information on the spatial and temporal variability of environment-related input variables (e.g., soil) and agricultural practices (e.g., sowing dates) that influence crop yields. Satellite remote sensing data can shed light on such variability by providing timely information on crop dynamics and conditions over large areas. This paper proposes a method for analyzing time series of MODIS satellite data in order to estimate the inter-annual variability of winter wheat sowing dates. A rule-based method was developed to automatically identify a reliable sample of winter wheat field time series, and to infer the corresponding sowing dates. The method was designed for a case study in the Camargue region (France), where winter wheat is characterized by vernalization, as in other temperate regions. The detection criteria were chosen on the grounds of agronomic expertise and by analyzing high-confidence time-series vegetation index profiles for winter wheat. This automatic method identified the target crop on more than 56% (four-year average) of the cultivated areas, with low commission errors (11%). It also captured the seasonal variability in sowing dates with errors of ±8 and ±16 days in 46% and 66% of cases, respectively. Extending the analysis to the years 2002-2012 showed that sowing in the Camargue was usually done on or around November 1st (±4 days). Comparing inter-annual sowing date variability with the main local agro-climatic drivers showed that the type of preceding crop and the weather conditions during the summer season before the wheat sowing had a prominent role in influencing winter wheat sowing dates.

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....

Sonoran Desert winter annuals affected by density of red brome and soil nitrogen

Science.gov (United States)

Salo, L.F.; McPherson, G.R.; Williams, D.G.

2005-01-01

Red brome [Bromus madritensis subsp. rubens (L.) Husn.] is a Mediterranean winter annual grass that has invaded Southwestern USA deserts. This study evaluated interactions among 13 Sonoran Desert annual species at four densities of red brome from 0 to the equivalent of 1200 plants ma??2. We examined these interactions at low (3 I?g) and high (537 I?g NO3a?? g soila??1) nitrogen (N) to evaluate the relative effects of soil N level on survival and growth of native annuals and red brome. Red brome did not affect emergence or survival of native annuals, but significantly reduced growth of natives, raising concerns about effects of this exotic grass on the fecundity of these species. Differences in growth of red brome and of the three dominant non nitrogen-fixing native annuals at the two levels of soil N were similar. Total species biomass of red brome was reduced by 83% at low, compared to high, N levels, whereas that of the three native species was reduced by from 42 to 95%. Mean individual biomass of red brome was reduced by 87% at low, compared to high, N levels, whereas that of the three native species was reduced by from 72 to 89%.

Vegetative, productive and qualitative performance of grapevine "Cabernet Sauvignon" according to the use of winter cover crops

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Jean Carlos Bettoni

Full Text Available ABSTRACT To study the effect of winter cover crops on the vegetative, productive and qualitative behavior of "Cabernet Sauvignon" grapevines, an experiment was conducted in two wine harvests by sowing different species of winter cover crops and additional treatments with manual weeding and mechanical mowing in an experimental vineyard located at the Experimental Station of Epagri in Videira, state of Santa Catarina, Brazil. Plant attributes of the grapevine, such as number of rods and weight of pruned material and number of branches per plant. At the time of skin color change, petioles of recently matured leaves were collected for analysis of the levels of N, P, K, Ca, Mg, Fe, Mn, Zn and B. Moments before harvest, 100 grape berries were collected randomly to determine the total soluble solids, titratable acidity and pH. At harvest, the number of bunches per branch, the number and mass of clusters per plant and the average mass of clusters per plot were determined. Fresh and dry matter yields of the cover crop and weed plants were also determined when coverage reached full bloom. The winter cover crops did not alter the yield and quality of "Cabernet Sauvignon" grapes and showed no differences from each other for the management of spontaneous vegetation by hand weeding or mechanical mowing. Rye and ryegrass are effective alternatives for weed control alternatives. The species of white and red clover present difficulty in initial establishment, producing a small amount of biomass.

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

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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.

Weed suppression greatly increased by plant diversity in intensively managed grasslands: A continental-scale experiment.

Science.gov (United States)

Connolly, John; Sebastià, Maria-Teresa; Kirwan, Laura; Finn, John Anthony; Llurba, Rosa; Suter, Matthias; Collins, Rosemary P; Porqueddu, Claudio; Helgadóttir, Áslaug; Baadshaug, Ole H; Bélanger, Gilles; Black, Alistair; Brophy, Caroline; Čop, Jure; Dalmannsdóttir, Sigridur; Delgado, Ignacio; Elgersma, Anjo; Fothergill, Michael; Frankow-Lindberg, Bodil E; Ghesquiere, An; Golinski, Piotr; Grieu, Philippe; Gustavsson, Anne-Maj; Höglind, Mats; Huguenin-Elie, Olivier; Jørgensen, Marit; Kadziuliene, Zydre; Lunnan, Tor; Nykanen-Kurki, Paivi; Ribas, Angela; Taube, Friedhelm; Thumm, Ulrich; De Vliegher, Alex; Lüscher, Andreas

2018-03-01

Grassland diversity can support sustainable intensification of grassland production through increased yields, reduced inputs and limited weed invasion. We report the effects of diversity on weed suppression from 3 years of a 31-site continental-scale field experiment.At each site, 15 grassland communities comprising four monocultures and 11 four-species mixtures based on a wide range of species' proportions were sown at two densities and managed by cutting. Forage species were selected according to two crossed functional traits, "method of nitrogen acquisition" and "pattern of temporal development".Across sites, years and sown densities, annual weed biomass in mixtures and monocultures was 0.5 and 2.0 t  DM ha -1 (7% and 33% of total biomass respectively). Over 95% of mixtures had weed biomass lower than the average of monocultures, and in two-thirds of cases, lower than in the most suppressive monoculture (transgressive suppression). Suppression was significantly transgressive for 58% of site-years. Transgressive suppression by mixtures was maintained across years, independent of site productivity.Based on models, average weed biomass in mixture over the whole experiment was 52% less (95% confidence interval: 30%-75%) than in the most suppressive monoculture. Transgressive suppression of weed biomass was significant at each year across all mixtures and for each mixture.Weed biomass was consistently low across all mixtures and years and was in some cases significantly but not largely different from that in the equiproportional mixture. The average variability (standard deviation) of annual weed biomass within a site was much lower for mixtures (0.42) than for monocultures (1.77). Synthesis and applications . Weed invasion can be diminished through a combination of forage species selected for complementarity and persistence traits in systems designed to reduce reliance on fertiliser nitrogen. In this study, effects of diversity on weed suppression were

Spatial and temporal distribution of weeds in no-tillage system

Directory of Open Access Journals (Sweden)

Eduardo L. Bottega

Full Text Available ABSTRACT Brazil is one of the largest grain producers in the world, due to its extensive arable land and favorable climate for the cultivation of any species. The production could be higher, but problems such as competition between crops and weeds reduces crop yields. This study aimed to analyze the spatial distribution of weeds, especially milkweed (Sonchus oleraceus, horse weed (Conyza spp. and ‘maria-mole’ (Senecio brasiliensis in an area under no-tillage system for two harvests. The work was carried out during the 2013/14 and 2014/15 crop years in an area of 22.5 ha, where soybean is grown in the summer and oat in the winter. The weeds were mapped using a sampling grid of 85 points. The number of plants present in 0.25 m2 was recorded at each sampling point. The data collected in the field composed the information bank and were used for geostatistical analysis and production of maps. Using geostatistical analysis, it was possible to map the horseweed infestation in the studied area for the 2013/14 season. The species ‘maria-mole’ and milkweed did not show spatial dependence. During the 2014/2015 season, because of the management carried out in the off season, none of the studied species showed spatial dependence.

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

Weed seed spread and its prevention: The role of roadside wash down.

Science.gov (United States)

Bajwa, Ali Ahsan; Nguyen, Thi; Navie, Sheldon; O'Donnell, Chris; Adkins, Steve

2018-02-15

Vehicles are one of the major vectors of long-distance weed seed spread. Viable seed removed from vehicles at roadside wash down facilities was studied at five locations in central Queensland, Australia over a 3-year period. Seed from 145 plant species, belonging to 34 different families, were identified in the sludge samples obtained from the wet particulate matter collection pit of the wash down facilities. Most of the species were annual forbs (50%) with small or very small seed size (weed was observed in these samples. More parthenium weed seed were found in the Rolleston facility and in the spring, but its seed was present in all facilities and in all seasons. The average number of viable seed found within every ton of dry particulate matter removed from vehicles was ca. 68,000. Thus, a typical wash down facility was removing up to ca. 335,000 viable seed from vehicles per week, of which ca. 6700 were parthenium weed seed. Furthermore, 61% of these seed (ca. 200,000) were from introduced species, and about half of these (35% of total) were from species considered to be weeds. Therefore, the roadside wash down facilities found throughout Queensland can remove a substantial amount of viable weed seed from vehicles, including the invasive parthenium weed, and the use of such facilities should be strongly encouraged. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Plight of Migrant Birds Wintering in the Caribbean: Rainfall Effects in the Annual Cycle

Directory of Open Access Journals (Sweden)

Joseph M. Wunderle, Jr.

2017-04-01

Full Text Available Here, we summarize results of migrant bird research in the Caribbean as part of a 75th Anniversary Symposium on research of the United States Department of Agriculture Forest Service, International Institute of Tropical Forestry (IITF. The fate of migratory birds has been a concern stimulating research over the past 40 years in response to population declines documented in long-term studies including those of the IITF and collaborators in Puerto Rico’s Guánica dry forest. Various studies indicate that in addition to forest loss or fragmentation, some migrant declines may be due to rainfall variation, the consequences of which may carry over from one stage of a migrant’s annual cycle to another. For example, the Guánica studies indicate that rainfall extremes on either the temperate breeding or tropical wintering grounds affect migrant abundance and survival differently depending on the species. In contrast, IITF’s collaborative studies of the migrant Kirtland’s Warbler (Setophaga kirtlandii in the Bahamas found that late winter droughts affect its annual survival and breeding success in Michigan. We review these IITF migrant studies and relate them to other studies, which have improved our understanding of migrant ecology of relevance to conservation. Particularly important is the advent of the full annual cycle (FAC approach. The FAC will facilitate future identification and mitigation of limiting factors contributing to migrant population declines, which for some species, may be exacerbated by global climate change.

The effect of species, planting date, and management of cover crops on weed community in hybrid sunflower (Helianthus annuus

Directory of Open Access Journals (Sweden)

M. Bolandi Amoughein

2016-02-01

Full Text Available Introduction: Studies showed that if mixed populations of annual weeds grow with the sunflower, for every 10% increase in weed biomass, seed yield would decrease by 13% (Van Gessel & Renner, 2000. In addition to control weeds using herbicides multi-stage spraying is required. In organic farming systems mulch is used to control weeds, protection, fertility and improve soil quality (Glab & Kulig, 2008; Kuchaki et al., 2001. Surface mulches from cover crops suppress weed growth by reducing light levels at the soil surface, thereby slowing photosynthesis. In return, these conditions reduce seed germination and act as a physical barrier to seedling emergence and growth (Teasdale et al., 2007. Materials and Methods: The experiment was carried out in Ardabil Agricultural Research Station, as a factorial experiment based on randomized complete block design with three replications during 1390-1391. The first factor was considered four types of cover crops including winter rye (Secale cereal, spring barley (Hordeum vulgare, winter wheat (Triticum aestivum and control (no cover crop, no weeding.The second factor was mulch management at two levels (living mulch and dead mulch and the third factor was two planting dates for cover crops (synchronous with sunflower planting and 45 days after sunflower planting. Sunflower seeding performed manually on 23 May on the ridges with 50 cm row distance and spacing between plants was 25 cm in depth of 5 cm. Cover crops seeds, rye, barley and wheat, were planted between rows of sunflower. Due to the low density of weeds in study field, complete weeding and sampling of weeds in one session was performed (60 days after planting date sunflower. Statistical analysis of data performed using SAS software and mean comparison performed using Duncan's test with probability level of 5% and 1%. Diagrams drawn using Excel (Version 8.2. Results and Discussion\t: Density and dry weight of Field bindweed (Convolvulus arvensis L

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...

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...

Organic fields sustain weed metacommunity dynamics in farmland landscapes.

Science.gov (United States)

Henckel, Laura; Börger, Luca; Meiss, Helmut; Gaba, Sabrina; Bretagnolle, Vincent

2015-06-07

Agro-ecosystems constitute essential habitat for many organisms. Agricultural intensification, however, has caused a strong decline of farmland biodiversity. Organic farming (OF) is often presented as a more biodiversity-friendly practice, but the generality of the beneficial effects of OF is debated as the effects appear often species- and context-dependent, and current research has highlighted the need to quantify the relative effects of local- and landscape-scale management on farmland biodiversity. Yet very few studies have investigated the landscape-level effects of OF; that is to say, how the biodiversity of a field is affected by the presence or density of organically farmed fields in the surrounding landscape. We addressed this issue using the metacommunity framework, with weed species richness in winter wheat within an intensively farmed landscape in France as model system. Controlling for the effects of local and landscape structure, we showed that OF leads to higher local weed diversity and that the presence of OF in the landscape is associated with higher local weed biodiversity also for conventionally farmed fields, and may reach a similar biodiversity level to organic fields in field margins. Based on these results, we derive indications for improving the sustainable management of farming systems. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Vitality structure of the populations of some weed species in crop sowings

Directory of Open Access Journals (Sweden)

E. M. Tikhonova

2010-11-01

Full Text Available Features of development of populations of weed species (Cirsium arvense (L. Scop., Sonchus arvensis L., Melandium album (Mill. Garke, Setaria glauca (L. Beauv., Fallopia convolvulus (L. А. Lоve in most typical crops in the forest-steppe zone of the Sumy region. It was studied the crop sowings (winter wheat, rye, barley, buckwheat, pea which was not subjected to the herbicide treatment.

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 ...

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, ...

Characterisation of the weed suppressive potential of winter cereal cultivars: the role of above-ground competition versus allelopathy in wheat, triticale and rye

DEFF Research Database (Denmark)

Reiss, Antje; Fomsgaard, Inge S.; Mathiassen, Solvejg Kopp

2016-01-01

Current weed management practices in Northern Europe are based primarily on the use of effective herbicides but an increase in the number of herbicide resistant weed phenotypes and a complete lack of new modes of action have led to an urgent need for more integrated weed management tactics. A bet...

Do green manures as winter cover crops impact the weediness and crop yield in an organic crop rotation?

OpenAIRE

Madsen, Helena; Talgre, Liina; Eremeev, Viacheslav; Alaru, Maarika; Kauer, Karin; Luik, Anne

2016-01-01

The effects of different winter cover crops and their combination with composted cattle manure on weeds and crop yields were investigated within a five-field crop rotation (barley undersown with red clover, red clover, winter wheat, pea, potato) in three organic cropping systems. The control system (Org 0) followed the rotation. In organic systems Org I and Org II the winter cover crops were used as follows: ryegrass (Lolium perenne L. in 2011/2012) and a mixture of winter oilseed-rape (Brass...

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.

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.

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

Effects of long-term reduced tillage on weed infestation of pea (Pisum sativum L.

Directory of Open Access Journals (Sweden)

Andrzej Woźniak

2014-09-01

Full Text Available The study evaluated weed infestation of pea (Pisum sativum L. cultivated under conditions of conventional (CT, reduced (RT and herbicide tillage (HT. It demonstrated the highest weed density per m2 in plots with the herbicide (HT and reduced (RT systems and significantly lower weed infestation in plots cultivated in the conventional system (CT. In addition, more weeds occurred at the third leaf stage (13/14 in BBCH scale than at the pod development stage (73/74 BBCH of pea. The highest biomass was produced by weeds in the herbicide system (HT, a lower one – in the reduced system (RT, and the lowest one – in the conventional system (CT. The air-dry weight of weeds depended also on pea development stage. At the pod development stage (73/74 BBCH, the air-dry weight of weeds was significantly higher than at the third leaf stage (13/14 BBCH. The tillage system was also observed to influence the species composition of weeds. This trait was also affected by the period of weed infestation assessment. At the third leaf stage of pea (13/14 BBCH, there occurred 26 weed species, including 24 annual ones. The most abundant species included: Chenopodium album L., Stellaria media (L. Vill., Capsella bursa-pastoris (L. Med., Matricaria inodora L., Thlaspi arvense L., and Fallopia convolvulus (L. A. Löve. At the pod development stage (73/74 BBCH, the pea crop was colonized by 24 weed species, including 3 perennial ones. At this stage the predominant species included: Avena fatua L., Amaranthus retroflexus L., Papaver rhoeas L., Echinochloa crus-galli (L. P.B., Matricaria inodora L., and Galeopsis tetrahit L.

Allelochemicals Effect of Aqueous Leachate from Oudneya Africana R

African Journals Online (AJOL)

nesrine

2014-03-05

Mar 5, 2014 ... This present study was conducted to investigate the possible allelopathic effect of Oudneya africana. (donor species) on Bromus tectorum (weed species) and Triticum aestivum (cv. Sahel1; crop species) through germination bioassay experiment. B. tectorum is a winter annual grass that grows in winter.

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 ...

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...

Zimbabwean fourth social workers conference and winter school ...

African Journals Online (AJOL)

Such steps include running the Annual Social Workers Conference & Winter School. This annual observance creates a platform to showcase the goals and accomplishments of diverse social work professionals in the country, give a report on progress and convening a social work winter school for exchanging professional ...

Allelotoxicity of Oudneya africana R. Br. aqueous leachate on ...

African Journals Online (AJOL)

This present study was conducted to investigate the possible allelopathic effect of Oudneya africana (donor species) on Bromus tectorum (weed species) and Triticum aestivum (cv. Sahel1; crop species) through germination bioassay experiment. B. tectorum is a winter annual grass that grows in winter wheat and other ...

A bioenergy feedstock/vegetable double-cropping system

Science.gov (United States)

Certain warm-season vegetable crops may lend themselves to bioenergy double-cropping systems, which involve growing a winter annual bioenergy feedstock crop followed by a summer annual crop. The objective of the study was to compare crop productivity and weed communities in different pumpkin product...

Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

Science.gov (United States)

Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

2012-01-01

Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

Climate Effects and Feedback Structure Determining Weed Population Dynamics in a Long-Term Experiment

Science.gov (United States)

Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

2012-01-01

Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements. PMID:22272362

Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

Directory of Open Access Journals (Sweden)

Mauricio Lima

Full Text Available Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors. Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

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

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.

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

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.

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 ...

Vertical distribution and composition of weed seeds within the plough layer after eleven years of contrasting crop rotation and tillage schemes

DEFF Research Database (Denmark)

Scherner, Ananda; Melander, Bo; Kudsk, Per

2016-01-01

Tillage methods and crop rotation are probably the two most important cropping factors affecting weed communities, particularly when herbicide use is restricted. This study examined weed dynamics following eleven years of different tillage and crop rotation treatments. The aboveground grass weed...... flora was recorded each year and the content and vertical location of individual weed seeds within the plough layer (0–20 cm) were determined after 11 years of continuous mouldboard ploughing (P), pre-sowing tine cultivation to 8–10 cm soil depth (H8-10) and direct drilling (D). The content of weed...... seeds, especially grass weeds, was determined for three distinct soil layers (0–5, 5–10 and 10–20 cm), reflecting the cultivation depths of the tillage treatments. The annual grass weeds, Apera spica-venti and Vulpia myuros, were promoted by non-inversion tillage and in the case of V. myuros also...

Evaluation of the Impact of Weed Control Methods on Quantitative and Qualitative Characteristics of Moldavian Balm; A Medicinal Plant

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Janmohammadi Mohsen

2016-12-01

Full Text Available Moldavian balm is an annual herbaceous plant and its lemon-scented leaves contain essential oil. However, weeds adversely affect its growth by release of allelochemicals, and/or direct competition for nutrient, moisture, light and space. Current experiment was conducted to evaluate the different weed control methods including preventive approach (soil pasteurization, mechanical methods (one hand weeding, two hand weeding, and successive hand weeding for weed free condition, and chemical control by synthetic herbicides (haloxyfop-R-methyl and trifluralin. Results revealed that stem diameter, quantity of secondary branches, flower-bearing branches and leaves were significantly affected by weed control treatments; the highest lateral growth was obtained by successive mechanical weed control and two hand weeding method, respectively. This trend was also observed in canopy spread and chlorophyll content. Pre-emergence control by trifluralin considerably accelerated the initiation of flowering in Moldavian balm. However, observation of qualitative traits showed that the highest essential oil content and oil yield was obtained when the plants grew in weed free soil which was pasteurized. Considering the recognized essential oils, the most responsive composition was including Geranial, Geranyl acetate, Neral and Geraniol. The lowest amount of Neral was recorded in postemergence control performed by means of haloxyfop-R-methyl herbicide.

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.

Short- and full-season soybean in stale seedbeds versus rolled-crimped winter rye mulch

Science.gov (United States)

Late seedbed preparations (also known as stale or false seedbeds) are used by organic growers to reduce weed populations prior to crop planting. Rye mulches, derived from mechanically killed (rolled and crimped) winter rye cover crops, can serve the same purpose for spring-planted organic crops. Bot...

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...

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.

Diversity of weed communities in soybean [Glycine max (L.] crop growing under direct sowing depending on cover crops and different herbicide doses

Directory of Open Access Journals (Sweden)

Elżbieta Harasim

2016-12-01

Full Text Available Despite being harmful for agricultural production, weeds are an essential component of biodiversity in agricultural landscapes. A field study was conducted during the period 2007–2009 on grey-brown podzolic soil (sandy, designated as PWsp, with the granulometric composition of silt and classified Class 2 in agricultural land suitability. The study evaluated the structure of weed communities based on selected indicators of diversity of a soybean crop grown under no-tillage with mulch from winter rye, winter oilseed rape, and white mustard as well as using herbicide rates reduced by 25% and 50% in relation to the standard rate (2 L ha−1. The studied factors were as follows: (i mulch plant species and mulch management method; (ii rates of the foliar herbicide Basagran 600 SL (a.i. bentazon; 600 g L−1. The results of this study confirm that no-tillage with mulch significantly changes the diversity of weed flora in a soybean crop. Among the mulches used, the mowed rye and winter oilseed rape in particular increased the values of the general diversity (H', species richness (d, and evenness (J' indices relative to the control treatment. On the other hand, the study found a strong decrease in the value of the dominance index (c. Reduced herbicide rates modified only the species richness index, in the case of which the 75% rate resulted in its significantly higher values compared to the full rate.

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

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 ...

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.

Chemical Weed Control in Saffron (Crocus sativus Fields

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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

Can global weed assemblages be used to predict future weeds?

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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.

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.

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...

Determination of Cardinal Temperatures for Cool Season Turfgrass and Two Common Weed Species

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Marjan Diayanat

2018-02-01

Full Text Available Introduction The presence of broadleaf weeds not only reduces the aesthetic quality of the turfgrass, but more importantly they compete with desired turfgrass for water, nutrients, and light. Weed management after seeding is an important component to successfully establishing a healthy stand of cool season turfgrass. Weed seed germination is a key process because determines both the number of weeds that could potentially emerge and the timing of their appearance in the turfgrass. Temperature is of the most important factor regulating germination of non-dormant seeds in irrigated, annual agroecosystems at the beginning of the growth season where light, nutrients, and moisture are typically not growth limiting. Also prostrate knotweed (Polygonum aviculare L. and annual sowthistle (Sonchus oleraceus L. are two annual common broad leaf weeds in cool season turfgrass. Prostrate knotweed is very competitive in infertile and compacted soils and often invades turfgrasses along driveways, sidewalks, and beaten paths across lawns. Annual sowthistle is found in open habitats that include waste areas, turf, and roadsides. The aim of this study was to evaluate different nonlinear regression models to describe response of germination rate to different temperatures in perennial ryegrass (Lolium perenne L., fescue (Festuca rubra L., prostrate knotweed and annual sowthistle. Materials and Methods This experiment was based on completely randomized design with 4 replications at Islamic Azad University in the laboratory of Science Research Branch in 2015. The seeds were treated with different temperatures (2, 5, 10, 15, 20, 25, 30, 35, 40 and 45oC Twenty five seeds were placed in each petri dish for each species in per replication. Ten milliliters of distilled water were added to each petri dish and the filter papers were regularly moistened to ensure saturation throughout the germination tests. Petri dishes were placed in germinator with 16 hour day, 8 hour night

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...

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

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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.

Vegetative, productive and qualitative performance of grapevine "Cabernet Sauvignon" according to the use of winter cover crops

OpenAIRE

Bettoni, Jean Carlos; Feldberg, Nelson Pires; Nava, Gilberto; Veiga, Milton da; Wildner, Leandro do Prado

2016-01-01

ABSTRACT To study the effect of winter cover crops on the vegetative, productive and qualitative behavior of "Cabernet Sauvignon" grapevines, an experiment was conducted in two wine harvests by sowing different species of winter cover crops and additional treatments with manual weeding and mechanical mowing in an experimental vineyard located at the Experimental Station of Epagri in Videira, state of Santa Catarina, Brazil. Plant attributes of the grapevine, such as number of rods and weight ...

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

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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.

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

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

Investigation of weed species diversity and community structure in saffron fields of Khorasan

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Surur Khorramdel

2017-09-01

Full Text Available Weedy flora of agroecosystems is composed of many species that have evolved in response to cropping system practices by occupying the niches left available in agroecosystems. In order to study weed species diversity and community structure in the saffron fields of Khorasan province, a survey trial was carried out in seven counties (including Mashhad, Neyshabur, Birjandn, Ghaen, Gonabad, Torbat-e Jam and Torbat-e Heydari during 2014 and 2015 from vegetative growth, dormant to flowering stages of saffron randomly dropped 1×1 m2 quadrates in 50 fields based on a systematic method as W pattern. The counties were clustered by the hierarchical complete linkage method based on Euclidean. Biodiversity indices such as stability coefficient, Simpson, Shannon–Wiener, Margalef and Menhinick were computed. The results indicated that the dominant weeds in saffron fields belong to 19 families and 50 species. Poaceae, Brassicaceae, Asteraceae and Fabaceae were dominant families with 11, 9, 8 and 6 species, respectively. The majority of weed species were dicotyledonous, C3, noxious and annual plants. The highest stability coefficients in the stages of growth of saffron were calculated in Alhagi camelorum, Avena fatua and Achillea millefolium to be 30.81, 24.11 and 12.14, respectively. All weed species except for Alhagi camelorum (sustainable species and Avena fatua (temporary species were recognized as causal species. The maximum diversity indices for weed species were recorded at the vegetative phase of saffron. Correlation coefficient between weed density and yield loss of saffron was computed as R2=0.98. Based on diversity indices for weed species, different counties were clustered in three groups at 75% similarity level.

The influence of intercrop plants and the date of their ploughing-in on weed infestation of root chicory (Cichorium intybus L. var. sativum (Bisch. Janch.

Directory of Open Access Journals (Sweden)

Marzena Błażewicz-Woźniak

2012-12-01

Full Text Available The field experiment was carried out in 2006-2008 in the Felin Experimental Farm (University of Life Sciences in Lublin on podzolic soil developed from dusty medium loam. Root chicory (Cichorium intybus L. var. sativum (Bisch. Janch. cv. Polanowicka was involved in the experiment. The experimental factors were 3 species of intercrop plants: common vetch (Vicia sativa, phacelia (Phacelia tanacetifolia, oat (Avena sativa and 2 dates of ploughing-in: pre-winter and spring. In total, 26 taxons characteristic for vegetable plantations were identified in chicory weed infestation. Monocarpic species dominated, among which Senecio vulgaris, Chenopodium album, Lamium amplexicaule, Galinsoga ciliata, and Capsella bursa-pastoris were predominant. The date of ploughing-in did not significantly affect the status and size of weed infestation of chicory plots. Short-lived species occurred after pre-winter ploughing-in, while perennial - after spring ploughing-in. The application of intercrops significantly reduced chicory weed infestation as compared to the cultivation with no intercrop. The ploughing-in of Avena sativa biomass appeared to be the most efficient. The intercrop plants reduced the occurrence of Senecio vulgaris and Capsella bursa-pastoris which were the most numerous in the treatment without intercrops. Biomass of Vicia sativa favored the growth of Chenopodium album and Lamium amplexicaule. The secondary weed infestation did not depend on agrotechnical factors applied during the experiment.

Pseudomonas fluorescens strains selectively suppress annual bluegrass (Poa annua L.)

Science.gov (United States)

Annual bluegrass (Poa annua L.) is a cool-season annual grass that is a major weed species in turf, turfgrass-seed production, sod production, and golf courses of the western United States. There are few selective herbicides available for the management of annual bluegrass. While the life cycles o...

Optical parameters of leaves of seven weed species

Science.gov (United States)

Gausman, H. W.; Menges, R. M.; Richardson, A. J.; Walter, H.; Rodriguez, R. R.; Tamez, S. (Principal Investigator)

1982-01-01

The absorption coefficient (k), infinite reflectance (R), and scattering coefficient (s) were tabulated for five wavelengths and analyzed for statistical differences for seven weed species. The wavelengths were: 0.55-micrometer, 0.65-micrometers, 0.85-micrometer, 1.65-micrometers, and 2.20-micrometer. The R of common lambsquarters (Chenopodium album L.), Johnsongrass (Sorghum halepense (L.) Pers.), and annual sowthistle (Sonchus oleraceus L.) leaves at the 0.85-micrometer wavelength were significantly (p=0.05) higher than for sunflower (Heliantus annus L.), ragweed parthenium (Parthenium hysterophorus L.), or London rocket (Sisymbrium irio L.). Annual sowthistle had the largest k value, and Plamer amaranth (Amaranthus palmer S. Wats.) had the smallest k value at the 0.65 approximately chlorophyll absorption wavelength. In general, john-songress, ragweed parthenium, or London rocket had the largest s values among the five wavelengths, wereas annual sowthistle and plamar amaranth were usually lowest.

Screening of a new cadmium hyperaccumulator, Galinsoga parviflora, from winter farmland weeds using the artificially high soil cadmium concentration method.

Science.gov (United States)

Lin, Lijin; Jin, Qian; Liu, Yingjie; Ning, Bo; Liao, Ming'an; Luo, Li

2014-11-01

A new method, the artificially high soil cadmium (Cd) concentration method, was used to screen for Cd hyperaccumulators among winter farmland weeds. Galinsoga parviflora was the most promising remedial plant among 5 Cd accumulators or hyperaccumulators. In Cd concentration gradient experiments, as soil Cd concentration increased, root and shoot biomass decreased, and their Cd contents increased. In additional concentration gradient experiments, superoxide dismutase and peroxidase activities increased with soil Cd concentrations up to 75 mg kg(-1) , while expression of their isoenzymes strengthened. Catalase (CAT) activity declined and CAT isoenzyme expression weakened at soil Cd concentrations less than 50 mg kg(-1) . The maxima of Cd contents in shoots and roots were 137.63 mg kg(-1) and 105.70 mg kg(-1) , respectively, at 100 mg kg(-1) Cd in soil. The root and shoot bioconcentration factors exceeded 1.0, as did the translocation factor. In a field experiment, total extraction of Cd by shoots was 1.35 mg m(-2) to 1.43 mg m(-2) at soil Cd levels of 2.04 mg kg(-1) to 2.89 mg kg(-1) . Therefore, the artificially high soil Cd concentration method was effective for screening Cd hyperaccumulators. Galinsoga parviflora is a Cd hyperaccumulator that could be used to efficiently remediate Cd-contaminated farmland soil. © 2014 SETAC.

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

Biology and management of Avena fatua and Avena ludoviciana: two noxious weed species of agro-ecosystems.

Science.gov (United States)

Bajwa, Ali Ahsan; Akhter, Muhammad Javaid; Iqbal, Nadeem; Peerzada, Arslan Masood; Hanif, Zarka; Manalil, Sudheesh; Hashim, Saima; Ali, Hafiz Haider; Kebaso, Lynda; Frimpong, David; Namubiru, Halima; Chauhan, Bhagirath Singh

2017-08-01

Avena fatua and Avena ludoviciana are closely related grass weed species infesting a large number of crops around the world. These species are widely distributed in diverse agro-ecosystems from temperate to sub-tropical regions due to their unique seed traits, successful germination ecology, high competitive ability, and allelopathic potential. A. fatua is more widespread, adaptable, and problematic than A. ludoviciana. Both these species infest major winter and spring crops, including wheat, oat, barley, canola, maize, alfalfa, and sunflower, causing up to 70% yield losses depending on crop species and weed density. Chemical control has been challenged by large-scale herbicide resistance evolution in these weed species. A. fatua is the most widespread herbicide-resistant weed in the world, infesting about 5 million hectares in 13 countries. The use of alternative herbicides with different modes of action has proved effective. Several cultural practices, including diverse crop rotations, cover crops, improved crop competition (using competitive cultivars, high seed rates, narrow row spacing, altered crop geometry), and allelopathic suppression, have shown promise for controlling A. fatua and A. ludoviciana. The integrated use of these cultural methods can reduce the herbicide dose required, and lower dependency on herbicides to control these grasses. Moreover, integrated management may successfully control herbicide-resistant populations of these weed species. The use of integrated approaches based on the knowledge of biology and ecology of A. fatua and A. ludoviciana may help to manage them sustainably in the future.

Effect of Nitrogen Fertilizer on Weeds Growth and Emergence and Yield and Yield Components of Corn (Zea mays L.

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M. Gholamshahi

2017-01-01

Full Text Available Introduction: Corn is one of the important crops of poaceae family which has important role in supplying food for human societies. Corn is third food crop in world and it has high potential compare to other crops because of its C4 photosynthetic pathway. In addition, corn is a strong and fast growing plant but it is sensitive to competition with weeds. According studies, there are 25 to 30 problematic weeds in corn farms which they include annual and perennial species. Annual weeds life cycle is similar to corn life cycle, there for the most problem of weeds in corn is summer annual weeds. Damage of weeds is different and it depends on weeds density, species composition, time of emergence, crop variety and other factors. While non control of weeds depending on those density and Variety, corn yeild may be decrease of 15 to 90 percent. Weeds which germinate in a short time can compete with crop on light, water and nutrition sources. Most of the weeds show better reaction to fertilizers compare with crops. This subject is due to weeds ability to nutrition absorption and aggregation and their high performances. Most of the weeds species are more responsive than crops to application of nitrogen fertilizer. Furthermore, the growth of most of the weed species increases with increasing nitrogen. Therefore, the increase of nitrogen in farming systems can have impacts on weeds and crops competitiveness. However, weeds compete with crop about using light, nutrient, water and soil space and the result of this competition is yield losses. Moreover, nitrogen is necessary to increase yield and nitrogen fertilizer enhances corn competitiveness, especially early in the season due to the slow growth of the plant and is necessary to achieve optimal performance. Excessive of nitrogen fertilizer during the growing season is benefit for weeds. Therefore, in order to study the effects of nitrogen fertilizer in combination with weeds management on yield and yield

Competition for soil nitrate and invasive weed resistance of three shrub-steppe growth forms

Science.gov (United States)

Eamonn D. Leonard

2007-01-01

Determining mechanisms responsible for weed resistance and invasion success are two issues that have potential in aiding successful land management decisions. The first experiment evaluates the competitive effects of an invasive annual grass downy brome (Bromus tectorum L.), an invasive biennial forb dyer's woad (Isatis tinctoria...

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...

Effect of straw mulch residues of previous crop oats on the weed population in direct seeded faba bean in Organic Farming

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Massucati, Luiz Felipe Perrone

2014-02-01

Full Text Available Under conditions of Organic Farming, we investigated whether direct seeding of faba bean (Vicia faba L. into straw mulch from residues of precrop oats used for weed control enables at least occasional/opportunistic direct seeding in Organic Agriculture. Eight field trials were carried out at different study sites in North Rhine-Westphalia, Germany, in 2008-2009 and 2009-2010. Direct seeding (DS was performed into mulch layers of 0,4 and 6 t ha-1 of straw residues applied to the remaining stubble, simulating different yield levels of the precrop oats. LBS was used as a reference treatment, where straw was harvested, stubble tillage performed and seedbed prepared in fall and oil radish (Raphanus sativus grown as winter cover crop. Mouldboard ploughing combined with conventional seedbed preparation was performed in early spring to V. faba. Compared with LBS, straw mulch with subsequent direct seeding suppressed especially dicotyledonous annuals significantly. DS treatments with straw reduced the abundance of this group by 81 and 85% compared with LBS. Straw mulch resulted in effective suppression of photosensitive weeds such as Matricaria spp. and late germinating Chenopodium album. Grasses and perennial species occurred independent of the amount of straw. Compared with DS, the abundance of these weeds was reduced by 64 and 82% in LBS treatment. The shoot dry matter production of faba bean was retarded by DS compared with LBS, but significant yield losses could be avoided with straw residues of at least 4 t ha-1. Sufficient amount of straw of from the previous crop is a key criterion to facilitate organic no-till farming of faba bean in a suitable crop sequence when pressure of perennials and grasses is low.

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.

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…

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...

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.

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.

Are weeds hitchhiking a ride on your car? A systematic review of seed dispersal on cars.

Directory of Open Access Journals (Sweden)

Michael Ansong

Full Text Available When traveling in cars, we can unintentionally carry and disperse weed seed; but which species, and where are they a problem? To answer these questions, we systematically searched the scientific literature to identify all original research studies that assess seed transported by cars and listed the species with seed on/in cars. From the 13 studies that fit these criteria, we found 626 species from 75 families that have seed that can be dispersed by cars. Of these, 599 are listed as weeds in some part of the world, with 439 listed as invasive or naturalized alien species in one or more European countries, 248 are invasive/noxious weeds in North America, 370 are naturalized alien species in Australia, 167 are alien species in India, 77 are invasive species in China and 23 are declared weeds/invaders in South Africa. One hundred and one are classified as internationally important environmental weeds. Although most (487 were only recorded once, some species such as Chenopodium album, Poa pratensis and Trifolium repens were common among studies. Perennial graminoids seem to be favoured over annual graminoids while annual forbs are favoured over perennial forbs. Species characteristics including seed size and morphology and where the plants grew affected the probability that their seed was transported by cars. Seeds can be found in many different places on cars including under the chassis, front and rear bumpers, wheel wells and rims, front and back mudguards, wheel arches, tyres and on interior floor mats. With increasing numbers of cars and expanding road networks in many regions, these results highlight the importance of cars as a dispersal mechanism, and how it may favour invasions by some species over others. Strategies to reduce the risk of seed dispersal by cars include reducing seed on cars by mowing road verges and cleaning cars.

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.

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.

Perspectives in Winter Limnology: Closing the annual cycle of freezing lakes

NARCIS (Netherlands)

Salonen, K.; Leppäranta, M.; Viljanen, M.; Gulati, R.D.

2009-01-01

Winter has traditionally been considered as an ecologically insignificant season and, together with technical difficulties, this has led winter limnology to lag behind summer limnology. Recently, rapidly expanding interest in climate warming has increased water research in winter. It has also become

[Effect of tillage patterns on the structure of weed communities in oat fields in the cold and arid region of North China].

Science.gov (United States)

Zhang, Li; Zhang, Li; Wu, Dong-Xia; Zhang, Jun-Jun

2014-06-01

In order to clarify the effects of tillage patterns on farmland weed community structure and crop production characteristics, based on 10 years location experiment with no-tillage, subsoiling and conventional tillage in the cold and arid region of North China, and supplementary experiment of plowing after 10 years no-tillage and subsoiling, oat was planted in 2 soils under different tillage patterns, and field weed total density, dominant weed types, weed diversity index, field weed biomass and oats yield were measured. The results showed that the regional weed community was dominated by foxtail weed (Setaira viridis); the weed density under long-term no-tillage was 2.20-5.14 times of tillage at different growing stages of oat, but there were no significant differences between conditional tillage and plowing after long-term no-tillage and subsoiling. Field weed Shannon diversity indices were 0.429 and 0.531, respectively, for sandy chestnut soil and loamy meadow soil under no-tillage conditions, and field weed biomass values were 1.35 and 2.26 times of plowing treatment, while the oat biomass values were only 2807.4 kg x hm(-2) and 4053.9 kg x hm(-2), decreased by 22.3% and 46.2%, respectively. The results showed that the weed community characteristics were affected by both tillage patterns and soil types. Long-term no-tillage farmland in the cold and arid region of North China could promote the natural evolution of plant communities by keeping more perennial weeds, and the plowing pattern lowered the annual weed density, eliminated perennial weeds with shallow roots, and stimulated perennial weeds with deep roots.

Chemical Control of Curled Dock (Rumex crispus L. and Other Weeds in Noncropped Areas

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Tsvetanka Dimitrova

2008-01-01

Full Text Available Rumex crispus L. is an invasive species widespread in our country and in particular in the region of North Bulgaria. It is characterized by high biological and ecological plasticity. Owing to its great reproductive potential, the weed has been assigned to the list of economically most important weeds in the country. With the purpose of studying the possibility of chemical weed control in noncropped areas with heavy natural background infestation with R. crispus L. and other dicotyledonous weeds, two field trials were carried out. A ready-to-use herbicide mixture 2,4-D 140.2 g/l-1 + Triclopyr 144 g/l-1, trade product Genoxon 3X (X0050, was tested at two doses of active ingredient, 3552 and 2842 ml/ha-1. It was found that: (1 population density of Rumex crispus L. can be successfully reduced by treatment at the stage of early stem formation; herbicideefficacy with 3552 and 2882 ml/ha-1 doses on the 21st day after treatment was 100% and 90.5%, respectively, at the end of vegetation 94.4 and 85.7%, respectively; (2 herbicidal efficacy was lower when R. crispus L. was treated at the 5 - 6 leaf stage, being 100 – 94.1%and 80 – 76.5% respectively for the indicated doses and time of recording; (3 at the studied doses the herbicide controlled both annual dicotyledonous weeds (Amaranthus spp., Chenopodium album L., Portulaca oleracea L. and perennial dicotyledonous ones (Cirsiumarvense L., Sonchus arvensis L., Convolvulus arvensis L., Carduus acanthoides L., but it was not toxic to monocotyledonous weeds.

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.

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...

Survey of Associations among Soil Properties and Climatic Factors on Weed Distribution in Wheat (Triticum aestivum L. in Kermanshah Province

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Mozhgan veisi

2016-11-01

Full Text Available Introduction Kermanshah province, Iran, comprises an area, of 24640 km2 and is located between 33°37′-35°17′N and 45°20′-48°1′E. The average annual precipitation is 450 mm. Most of the fields surveyed in this study lie between 542 and 1554 m a.s.l. Among the factors decreasing the wheat yields, weeds have an important role. The results of some researches show that the weeds flora depends on climatic conditions, temperature and amount of rainfall in spring and in summer. Environmental factor splay a key role in the weed cover. These differences affected by climatic conditions, latitude and longitude. Multivariate statistical methods that have been addressed in this study area powerful tool to study the relationship between environmental factors and ecological weed community composition (Hassannejad & Pourhaydar Ghafarbi, 2013; Lososova et al., 2004. Correlation and regression of data floristic and environmental factors were used in the CCA (Canonical Correspondence Analysis technique (Legendre & Legendre, 1998. Materials and methods A survey was conducted to study the effects of soil and climatic factors on distribution of weeds in 85 irrigated wheat fields in 11 counties based on its area under irrigated wheat. An Experiment was conducted in Kermanshah province during 2011-2012. After choosing the field to be surveyed, the surveyor followed a “w”-designated set pattern to enumerate the weeds in each type of field. The pattern and number of 0.25 m2 quadrats varied according to the size of the fields. The field surveys were made during the wheat tillering to stem elongation stages. Frequency, density and mean density index of species in each county were calculated. After weed species were collected in the fields, we arranged the samples into the first matrix where weed species are represented by columns and fields of different districts by rows. Also, in the second matrix, environmental factors are represented by columns and fields

Predicting Emergence of the Most Important Weed Species in Soybean (Glycine max L. under Different Management Operation

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R. Khakzad

2017-12-01

Full Text Available Introduction: Summer annual weeds typically germinate in spring and early summer, grow throughout the summer, and set seeds by fall. Summer annual weeds are a persistent problem in summer annual row crops, competing directly for water, light, and nutrients, causing yield losses in quantity and quality. Although agriculture is increasingly relying on modern technology, knowledge of the biological systems in which these technologies are used is still critical for implementation of management strategies. Biological information about weeds is valuable and necessary for developing management strategies to minimize their impact. Scouting fields for pest problems are essential in any cropping system and knowledge of the timing and sequence of weed species emergence could increase the effectiveness of weed scouting trips and subsequent management practices. The success of any annual plant is directly correlated to its time of seedling emergence because it determines the ability of a plant to compete with its neighbors, survive biotic and abiotic stresses, and reproduce. The period and pattern of emergence of the weed community depend on the species present in the seed bank and their interaction with the environment. Therefore, knowledge of the weed species present in the soil seed bank and when these species are most likely to emerge is important in planning effective weed control programs. Temperature has been reported to be the main environmental factor regulating germination and emergence of weed species. Scientists have developed TT models to predict the emergence of weed species based on a daily accumulation of heat units or growing degree days (GDD above a minimum base threshold value (Tbase. The predictive models for weed emergence based on the accumulation of TT appear to be accurate enough for projections of weed emergence time (Grundy 2003. Moreover, soil temperature data are easily accessible, making this type of model practical and useful to

WEED CONTROL EFFECTS ON SOIL CHEMICAL CHARACTERISTICS

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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.

Sistemas de cultivo no cerrado e dinâmica de populações de plantas daninhas Tillage systems in the cerrado and dinamics of weed populations

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F.A.R. Pereira

2003-12-01

Full Text Available O trabalho teve como objetivo avaliar os efeitos de sistemas de plantio direto, utilizando diferentes programas de rotação de culturas, de preparo convencional e de cultivo mínimo sobre a dinâmica de populações de plantas daninhas nas condições edafoclimáticas do cerrado. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições e cinco tratamentos, sendo dois de plantio direto que constaram de programas de rotação constituídos por culturas de verão e de outono/inverno e dois em monocultivo, nos sistemas de preparo convencional e cultivo mínimo respectivamente. Avaliou-se a dinâmica das populações de plantas daninhas. A maior eficiência de controle cultural da comunidade infestante foi obtida com o sistema de plantio direto, por meio dos seguintes programas de rotação: (sorgo/soja - crotalária/milho - milheto/soja - milho safrinha/soja; (milho safrinha/soja - girassol/milho - sorgo/soja - girassol/milho e (guandu/soja - milheto/soja - milho safrinha/milho - girassol/soja.This research aimed to evaluate the effects of no-tillage systems using crop rotation variations, conventional tillage, and minimum tillage on the dynamics of weed populations in the cerrado region in Brazil. The experiment was arranged in a randomized block design, four replications and five treatments, (two no tillage treatments consisting of summer and fall/winter crop rotations and two single crop treatments under conventional tillage and minimum tillage. Weed population dynamics was evaluated. The results showed that the no-tillage system was the most efficient for weed control with the following programs: soybean/sorghum - Crotalaria/corn - millet/soybean, winter corn/soybean; (winter corn/soybean - sunflower/corn - sorghum/soybean - sunflower/corn and (Pigeon/pea/soybean - millet/soybean - winter corn/corn - sunflower/soybean .

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…

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,

Achievements and problems in the weed control in grain sorghum (Sorghum Bicolor Moench.

Directory of Open Access Journals (Sweden)

Gr. Delchev

2017-09-01

Full Text Available Abstract. Chemical control has emerged as the most efficient method of weed control. Herbicides combinations and tank mixtures of herbicides with adjuvants, fertilizers, growth regulators, fungicides, insecticides are more effective than when applied alone on sorghum crops. Their combined use often leads to high synergistic effect on yield. The use of herbicide antidotes for the treatment of seeds in sorghum is a safe way to overcome its high sensitivity to many herbicides. Data regarding herbicide for chemical control of annual graminaceous weeds in sorghum crops are quite scarce even worldwide. Problem is the persistence of some herbicides used in the predecessors on succeeding crops, which is directly related to the weather conditions during their degradation. Most of the information on sorghum relates to the conventional technology for weed control. There is no information about the new Concep technology in grain sorghum. A serious problem is also the volunteers of the Clearfield and Express sun sunflower. They have resistance to herbicides different from that of conventional sunflower hybrids. There is no information yet in scientific literature on control of these volunteers.

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.

Evaluation of a model for predicting Avena fatua and Descurainia sophia seed emergence in winter rapeseed

Energy Technology Data Exchange (ETDEWEB)

Aboutalebian, M.A.; Nazari, S.; Gonzalez-Andujar, J.L.

2017-07-01

Avena fatua and Descurainia sophia are two important annual weeds throughout winter rapeseed (Brassica napus L.) production systems in the semiarid region of Iran. Timely and more accurate control of both species may be developed if there is a better understanding of its emergence patterns. Non-linear regression techniques are usually unable to accurately predict field emergence under such environmental conditions. The objectives of this research were to evaluate the emergence patterns of A. fatua and D. sophia and determine if emergence could be predicted using cumulative soil thermal time in degree days (CTT). In the present work, cumulative seedling emergence from a winter rapeseed field during 3 years data set was fitted to cumulative soil CTT using Weibull and Gompertz functions. The Weibull model provided a better fit, based on coefficient of determination (R2sqr), root mean square of error (RMSE) and Akaike index (AICd), compared to the Gompertz model between 2013 and 2016 seasons for both species. Maximum emergence of A. fatua occured 70-119 days after sowing or after equals 329-426 °Cd, while in D. sophia it occurred 119-134 days after sowing rapeseed equals 373-470 °Cd. Both models can aid in the future study of A. fatua and D. sophia emergence and assist growers and agricultural professionals with planning timely and more accurate A. fatua and D. sophia control.

Compounds of natural origin inducing resistance in winter wheat to powdery mildew (Blumeria graminis f.sp. tritici)

Czech Academy of Sciences Publication Activity Database

Věchet, L.; Martínková, J.; Šindelářová, Milada; Burketová, Lenka

2005-01-01

Roč. 51, č. 10 (2005), s. 469-475 ISSN 1214-1178 R&D Projects: GA ČR GA522/03/0353 Institutional research plan: CEZ:AV0Z50380511 Keywords : winter wheat * inducer of resistence * powdery mildew Subject RIV: GF - Plant Pathology, Vermin, Weed, Plant Protection Impact factor: 0.170, year: 2004

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.

TAXONOMY OF FUSARIUM SPECIES ISOLATED FROM CULTIVATED PLANTS, WEEDS AND THEIR PATHOGENICITY FOR WHEAT

Directory of Open Access Journals (Sweden)

Jasenka Ćosić

2002-06-01

Full Text Available Fusarium species are wide-spread and known to be pathogenic agents to cultivated plants in various agroclimatic areas. During a four year investigation 10 Fusarium species and Microdochium nivale were isolated from wheat, barley, maize and soybean as well as from 10 weeds collected from 10 locations in Slavonia and Baranya. Fusarium graminearum was dominant on wheat and barley, F. moniliforme on maize and F. oxysporum on soybean. Regarding weeds, the presence of the following Fusarium species was established: F. graminearum on Amaranthus hybridus, Capsella bursa-pastoris, Lamium purpureum, Sorghum halepense and Urtica dioica, F. moniliforme on Abutilon theophrasti, F. subglutinans on Polygonum aviculare, F. avenaceum on Capsella bursa-pastoris, Rumex crispus and Matricaria sp., F. culmorum on Abutilon theophrasti, F. sporotrichioides on Polygonum aviculare, F. proliferatum and F. poae on Artemisia vulgaris. Pathogenicity test to wheat seedlings was done in our laboratory on winter wheat cultivars Slavonija and Demetra (totally 146 isolates. The most pathogenic species to wheat seedilings were F. graminearum, F. culmorum and F. sporotrichioides and the least pathogenic F. moniliforme, F. solani, F. oxysporum and F. poae. Pathogenicity test for wheat ears was done on genotypes Osk.8c9/3-94 and Osk.6.11/2 (totally 25 isolates. The results obtained by our investigation showed that there were no significant differences in pathogenicity of Fusarium species isolated from both cultivated plants and weeds. Weeds represent a constant source of inoculum of F. species for cultivated plants and they serve as epidemiologic bridges among vegetations.

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...

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.

Atlantis Star – a new herbicide in cereals with efficacy against grasses and dicots

Directory of Open Access Journals (Sweden)

Kerlen, Dirk

2016-02-01

Full Text Available Atlantis Star (mesosulfuron-methyl; iodosulfuron-methyl-sodium; thiencarbazone-methyl; mefenpyr-diethyl is a new cereal herbicide to control blackgrass (Alopecurus myosuroides; sensitive and high infestation, brome grass (Bromus spec., ryegrass (Lolium spec., wild oat (Avena fatua, loose silky-bentgrass (Apera spica-venti L., annual meadow-grass (Poa annua L. and dicot weeds. Atlantis Star can be used in winter wheat, winter triticale, winter rye, winter durum wheat and spelt. The publication is based on efficacy trials from two years of spring application with Atlantis Star.

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.

Selectivity and weed control efficacy of some herbicides applied to sprinkler irrigated rice (Oryza sativa L.)

Energy Technology Data Exchange (ETDEWEB)

Cavero, J; Zaragoza, C; Cirujeda, A; Anzalone, A; Faci, J M; Blanco, O

2011-07-01

Sprinkler irrigation can reduce the irrigation water needed to grow rice. However, most available information on weed control with herbicides is related to flood irrigated rice because this is the main growing method. Field experiments were conducted at Zaragoza (Spain) during two years to study weed control and tolerance of sprinkler irrigated rice to several herbicides. The main weeds were Atriplex prostrata Boucher ex DC., Cyperus rotundus L., Echinochloa crus-galli (L.) Beauv. and Sonchus oleraceus L. Rice cv Guadiamar was tolerant to preemergence (PRE) application of clomazone at 0.36 kg ha{sup -}1 and oxadiazon at 0.5 kg ha{sup -}1. PRE application of pendimethalin at 1.32 kg ha{sup -}1 combined with clomazone at 0.36 kg ha{sup -}1 decreased rice yield. Postemergence (POST) application of bentazon at 1.6 kg ha{sup -}1 + MCPA at 0.25 kg ha{sup -}1 did not injure rice but POST application of azimsulfuron at 0.025 kg ha{sup -}1 produced visual crop injury. Only treatments that controlled grassy weeds since rice was planted and by more than 80% at harvest time lead to acceptable rice yield (> 5,000 kg ha{sup -}1). Clomazone applied PRE at 0.36 kg ha{sup -}1 provided good control of grassy weeds (> 80%) and the highest rice yield, so it is recommended as a selective and efficacious PRE treatment for weed control of annual weeds in sprinkler irrigated rice. The perennial purple nutsedge was difficult to control at high plant densities (> 150 plants m{sup -}2) and the recommended herbicide is azimsulfuron applied at POST at 0.02 kg ha{sup -}1. (Author) 37 refs.

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.

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.

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 ...

Weed supression by smother crops and selective herbicides

Directory of Open Access Journals (Sweden)

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.

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.

Weed emergence in autumn under temperate conditions Emergência de plantas daninhas no outono em condições temperadas

Directory of Open Access Journals (Sweden)

J.M.G. Calado

2011-06-01

Full Text Available The emergence of weed plants depends on environmental conditions, especially temperature and soil moisture. The latter is extremely important in Mediterranean environments which are characterized by irregular amount and distribution of rain throughout the year, which influences the beginning of the growth cycle of the annual species (seed germination. This paper studies the influence of rainfall, in particular accumulated rainfall in autumn, on the emergence of weed plants. The experiment was carried out on Luvisols, and the appearance of flora under field conditions was observed. Through analysis of the results, it can be concluded that a high percentage of weed plants (> 85% related to the highest registered value was obtained with more than 90 mm of accumulated rainfall from the beginning of September. Thus, in those years in which this amount of rainfall (90 mm is registered until the end of October, the appearance of potential weed plants can be ensured, under Mediterranean conditions, in a period before sowing the autumn-winter crops.A emergência de plantas daninhas depende das condições ambientais, sobretudo da temperatura e da umidade. Esta é de extrema importância em ambientes mediterrânicos, caracterizados pela irregularidade da quantidade de precipitação e da sua distribuição durante o ano, que influencia o início do ciclo vegetativo das espécies anuais (germinação de sementes. Neste trabalho, estudouse a influência da precipitação, particularmente a quantidade acumulada no outono, na emergência de plantas daninhas. O experimento foi realizado em Luvisols, tendo sido registrado o aparecimento da flora em condições de campo. De acordo com a análise dos resultados, conclui-se que elevadas densidades populacionais de plantas daninhas (> 85% relativamente ao valor máximo verificado foram obtidas com uma precipitação acumulada desde o início de setembro superior a 90 mm. Assim, nos anos em que se registra essa

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...

Simulation model for longterm management of Avena fatua L. in winter wheat

Directory of Open Access Journals (Sweden)

Jäck, Ortrud

2014-02-01

Full Text Available Decision support systems (DSS are used for weed control decisions worldwide. Several DSS for weed management have been published. However they mostly rely on full herbicide dosages and do not take weed population dynamics into account. We developed a modular DSS for long-term Avena fatua L. control in winter wheat. The DSS was parameterized with three year field experiment datasets covering yield loss data, densitydependent population dynamics data as well as data on dose dependent herbicide efficacy and dosedependent population dynamics. The DSS aims to control the A. fatua in the long run. Our hypothesis is that the optimized DSS reduces herbicide input while keeping the population density at low level, maintaining high grain yields and net return. The DSS comprises four sub-models calculating crop yield loss, A. fatua population dynamics as well as dose dependent herbicide efficacy and economics of the weed control decision. The economic sub-model calculates net return in dependency of the herbicide dosage and thus the resulting crop yield. First results of a 10-year simulation showed that herbicide input could be reduced by 40% compared to the economic threshold strategy, while the population density of A. fatua is controlled. Up to now the DSS has been parameterized for the herbicides Ralon Super, Axial 50 and Broadway. The results show the great potential of reducing herbicide input and point out the importance of including population dynamics models into DSS.

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

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…

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.

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.

Short communication: Evaluation of a model for predicting Avena fatua and Descurainia sophia seed emergence in winter rapeseed

Directory of Open Access Journals (Sweden)

Mohammad A. Aboutalebian

2017-07-01

Full Text Available Avena fatua and Descurainia sophia are two important annual weeds throughout winter rapeseed (Brassica napus L. production systems in the semiarid region of Iran. Timely and more accurate control of both species may be developed if there is a better understanding of its emergence patterns. Non-linear regression techniques are usually unable to accurately predict field emergence under such environmental conditions. The objectives of this research were to evaluate the emergence patterns of A. fatua and D. sophia and determine if emergence could be predicted using cumulative soil thermal time in degree days (CTT. In the present work, cumulative seedling emergence from a winter rapeseed field during 3 years data set was fitted to cumulative soil CTT using Weibull and Gompertz functions. The Weibull model provided a better fit, based on coefficient of determination (R2sqr, root mean square of error (RMSE and Akaike index (AICd, compared to the Gompertz model between 2013 and 2016 seasons for both species. Maximum emergence of A. fatua occured 70-119 days after sowing or after equals 329-426 °Cd, while in D. sophia it occurred 119-134 days after sowing rapeseed equals 373-470 °Cd. Both models can aid in the future study of A. fatua and D. sophia emergence and assist growers and agricultural professionals with planning timely and more accurate A. fatua and D. sophia control.

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.

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

Directory of Open Access Journals (Sweden)

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.

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

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...

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

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

Payment mechanisms for winter road maintenance services

Directory of Open Access Journals (Sweden)

Adel Abdi

2013-12-01

Full Text Available In countries with severe winters a major part of the annual budget for road maintenance is allocated on performance of winter road maintenance tasks. Finding appropriate remuneration forms to compensate entrepreneurs for performed road measures during winter is not an easy task in order to minimise or eliminate disputes and satisfy both client organisations and contractors. On the other hand improper reimbursement models lead either to the client’s annual budget imbalance due to unnecessary cost overruns or affect contractor’s cash-flow. Such cases in turn affect just-in-time winter road maintenance and then traffic safety. To solve such problems, a number of countries in cold regions like Sweden have developed different remuneration models based more on weather data called Weather Index. Therefore the objective of this paper is to investigate and evaluate the payment models applied in Sweden. The study uses a number of approaches namely; domestic questionnaire survey, analysis of a number of contract documents, a series of meetings with the project managers and an international benchmarking. The study recognised four remuneration models for winter maintenance service of which one based on weather data statistics. The study reveals the payment model based on weather data statistics is only applied for the roads with higher traffic flow and the model generates most uncertainty.

Comunidades de malezas en cultivos hortícolas en la Provincia de Neuquén (Argentina Weed's communities in vegetable crops in Neuquen Province, (Argentina

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María Beatriz Cerazo

2008-07-01

them included in the class Artemisietea vulgaris. Eighty nine species were tacked stock for the autumn -winter and spring - summer periods. There was a clear predominance of Dicotyledonous ( 79 % over Monocotyledonous and a predominance of annual weeds (66% over perennial weeds.

Energy and tannin extract supplementation for dairy cows on annual winter pastures

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Tiago Pansard Alves

2017-05-01

Full Text Available Energy supplementation can increase the consumption of metabolizable energy and substrate for microbial growth, while condensed tannins aid in increasing the duodenal flow of foodborne metabolizable proteins. The objective of this study was to evaluate the effects of energy supplementation and the inclusion of tannin extract (TE from Acacia mearnsii (Weibull Black, Tanac S. A., Montenegro, Brazil on the production performance of dairy cows grazing on winter pastures. Nine multiparous Holstein cows in mid lactation were distributed in a 3 × 3 Latin square experimental design over three periods of 28 days (21 adaptation and 7 sampling. The treatments were: without supplementation (WS, supplementation with 4 kg of corn grain (CG, and corn grain + 80 g of tannin extract (TE. The dry matter (DM intake from pastures was similar among treatments, but the consumption of DM of the supplement was higher in the CG treatment than that in the TE treatment. The total DM intake was higher for the supplemented animals (17.3 kg?day-1 than that for the unsupplemented animals (14.9 kg?day-1 and in the TE treatment (17.7 kg?day-1 than in the CG treatment (16.7 kg day-1. Milk production increased from the unsupplemented to the supplemented animals (20.9 to 23.5 kg, respectively, while the content of urea N in the milk decreased (12.6 to 10.5 mg?100 mL-1, respectively. There were no differences in milk production or content of milk urea N between the CG and TE treatments. Energy supplementation is a tool for improving the nutritional profile and the performance of dairy cows in mid lactation grazing on annual winter pastures, while tannin extract aids in improving the energy balance.

Weed detection using unmanned aircraft vehicles

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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.

Puncturevine (Tribulus terrestris L.: noxious weed or powerful medical herb

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Zvonko Pacanoski

2014-03-01

Full Text Available Tribulus terrestris L., an annual dicot species of the family Zygophyllaceae, is a common herb that is often found in disturbed habitats and agricultural areas in many parts of the temperate, tropical and desert regions of the world. T. terrestris is an aggressive species that has the potential to injure livestock, reduce hay and wool values, detour recreationists and reduces plant biodivesity. The species may become troublesome because of its weedy potential. It has been declared a weed in at least 37 countries and in at least 21 crops (cotton, maize, vineyards, orchards, etc.. It is adapted to a wide range of climatic conditions and grows on a wide variety of soil types. The management of T. terrestris can be achieved by herbicide application, mechanical (hand pulling, hoeing, mulching and biological control methods. Beside its invasive potential as a noxious and troublesome weed, T. terrestris is considered highly useful herb which is used for various purposes in folk and modern medicine and sport, as well.

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.

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.

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

Large-scale climate variation modifies the winter grouping behavior of endangered Indiana bats

Science.gov (United States)

Thogmartin, Wayne E.; McKann, Patrick C.

2014-01-01

Power laws describe the functional relationship between 2 quantities, such as the frequency of a group as the multiplicative power of group size. We examined whether the annual size of well-surveyed wintering populations of endangered Indiana bats (Myotis sodalis) followed a power law, and then leveraged this relationship to predict whether the aggregation of Indiana bats in winter was influenced by global climate processes. We determined that Indiana bat wintering populations were distributed according to a power law (mean scaling coefficient α = −0.44 [95% confidence interval {95% CI} = −0.61, −0.28). The antilog of these annual scaling coefficients ranged between 0.67 and 0.81, coincident with the three-fourths power found in many other biological phenomena. We associated temporal patterns in the annual (1983–2011) scaling coefficient with the North Atlantic Oscillation (NAO) index in August (βNAOAugust = −0.017 [90% CI = −0.032, −0.002]), when Indiana bats are deciding when and where to hibernate. After accounting for the strong effect of philopatry to habitual wintering locations, Indiana bats aggregated in larger wintering populations during periods of severe winter and in smaller populations in milder winters. The association with August values of the NAO indicates that bats anticipate future winter weather conditions when deciding where to roost, a heretofore unrecognized role for prehibernation swarming behavior. Future research is needed to understand whether the three-fourths–scaling patterns we observed are related to scaling in metabolism.

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.

Soil solarization for weed control in carrot

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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.

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

Impact of sowing density and nitrogen fertilization on Rumex obtusifolius L. development in organic winter cereal crops

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Bodson, B.

2012-01-01

Full Text Available The control of Rumex obtusifolius L. (broad-leafed dock is very important in organic farming systems. Indeed, concerns about managing this weed without the use of herbicides is one of the major factors limiting the uptake of these systems by conventional farmers. Against this background, we analyzed the impact of two management practices on the development of R. obtusifolius populations in two winter cereal trials: spelt (Triticum spelta [L.] Thell. and triticale (×Triticosecale [A.Camus] Wittm.. The management factors were sowing density (SD and nitrogen fertilization (NF at the tillering stage. The results showed that an increase in SD and NF led to stronger crop growth and better soil coverage by the end of spring, demonstrated by a significant decrease in photosynthetic active radiation (PAR at soil level. However, although there was an SD effect, it was too weak in April to restrict an increase in R. obtusifolius populations through the recruitment of new R. obtusifolius plants. An increase in R. obtusifolius population density was also linked to an increase in the NF level, illustrating the nitrophilic character of this weed. Although an increase in SD and NF at the tillering stage led to a higher canopy density, these two practices failed to reduce R. obtusifolius density in the cereal crops. Nevertheless, cereal yields were shown to be maintained or improved. Our results indicate that, even when combining weed harrowing and some cultural weed control methods, this perennial weed is difficult to control.

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...

Winter precipitation and fire in the Sonoran Desert

Energy Technology Data Exchange (ETDEWEB)

Rogers, G.F.; Vint, M.K.

1987-01-01

Historical fire and climate records from the Arizona Upland portion of the Tonto National forest were used to test the hypothesis that fires burn larger areas in the Sonoran Desert after two wet winters than after one. We found that many more hectares burn in years following two winters that are wetter than normal, than during any other years. We agree with other ecologists, that desert fire occurrence is probably related to increased production of winter annual plants, and we suggest ways that the relationship may be clarified.

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...

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...

Contrasting effects of temperature and winter mixing on the seasonal and inter-annual variability of the carbonate system in the Northeast Atlantic Ocean

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C. Dumousseaud

2010-05-01

Full Text Available Future climate change as a result of increasing atmospheric CO₂ concentrations is expected to strongly affect the oceans, with shallower winter mixing and consequent reduction in primary production and oceanic carbon drawdown in low and mid-latitudinal oceanic regions. Here we test this hypothesis by examining the effects of cold and warm winters on the carbonate system in the surface waters of the Northeast Atlantic Ocean for the period between 2005 and 2007. Monthly observations were made between the English Channel and the Bay of Biscay using a ship of opportunity program. During the colder winter of 2005/2006, the maximum depth of the mixed layer reached up to 650 m in the Bay of Biscay, whilst during the warmer (by 2.6 ± 0.5 °C winter of 2006/2007 the mixed layer depth reached only 300 m. The inter-annual differences in late winter concentrations of nitrate (2.8 ± 1.1 μmol l⁻¹ and dissolved inorganic carbon (22 ± 6 μmol kg⁻¹, with higher concentrations at the end of the colder winter (2005/2006, led to differences in the dissolved oxygen anomaly and the chlorophyll α-fluorescence data for the subsequent growing season. In contrast to model predictions, the calculated air-sea CO₂ fluxes (ranging from +3.7 to −4.8 mmol m⁻² d⁻¹ showed an increased oceanic CO₂ uptake in the Bay of Biscay following the warmer winter of 2006/2007 associated with wind speed and sea surface temperature differences.

Weed control by direct injection of plant protection products according to specific situations

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Krebs, Mathias

2016-02-01

Full Text Available Precision Farming in agriculture allows a site-specific management of the crop. The aim of plant protection is to apply plant protection products (PPP according to the site specific requirements on the field. Within the context of a research program to promote innovation, a sprayer with direct injection of plant protection products was developed. The direct injection offers site specific spraying of different individual PPP in a single pass. The sprayer prototype is equipped with a special spray boom combining three nozzle lines. In order to prevent delay times, the nozzle lines are preloaded before spraying. First results for weed control from test stand measurements and field trials showed that the injection pumps work with high accuracy. The prototype can be used without delay times site specific with up to three different herbicides. Field trials for site-specific weed control in winter wheat demonstrate the applicability of the system under practical conditions. By treatment of subareas herbicides and therefore costs could be saved. A reduction in yield compared with the conventionally treated field areas could not be ascertained. Also an efficacy reduction through washout of active ingredient from target surfaces due to simultaneous use of all three nozzle lines with up to 1050 l/ha application rate could not be detected. At high water spray rates, the efficacy effect occurs delayed. Overall, the newly developed direct injection system proved fieldabillity during the first tests. So weed control can be carried out situation-responsive, which can save herbicides and environmental impacts are reduced.

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).

A STUDY ON WEED CONTROL IN SOYBEAN

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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.

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 ...

Pyrenophoric acid, a phytotoxic sesquiterpenoid penta-2,4-dienoic acid produced by a potential mycoherbicide, Pyrenophora semeniperda

Science.gov (United States)

Marco Masi; Susan Meyer; Alessio Cimmino; Anna Andolfi; Antonio Evidente

2014-01-01

A new phytotoxic sesquiterpenoid penta-2,4- dienoic acid, named pyrenophoric acid, was isolated from solid wheat seed culture of Pyrenophora semeniperda, a fungal pathogen proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum) and other annual bromes. These bromes are serious weeds in winter cereals and also on temperate semiarid rangelands....

WHITE BLISTER SPECIES (Albuginaceae ON WEEDS

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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.

Impact of fungicides on weed growth

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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.

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

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...

Structural and Functional Diversity of Weed Species in Organic and Conventional Rice Agro-Ecosystems

Directory of Open Access Journals (Sweden)

S. Y. Mousawi Toghani

2016-02-01

-Wilson included two clusters in 83% and 82%, respectively. Range of similarity index was between 1.89% and 83.96%. Weed grouping based on relative frequency during the sampling stages showed two clusters in 78% and four clusters in 85% similarity. Clustering weeds centered on relative frequency during sampling stages, according to the family, showed different results. It might be the reason that the relative abundance of weeds, sedge family (79% were in two clusters. However, sampling stages grouping based on weed density, induced two clusters in 39% similarity. Both conventional and organic systems, are included 10 species of 8 genera of four families. The 75 percent of families based on the vegetative form were monocots and 25% of them were dicots, so monocots had more diversity. Perhaps the presence of Alismaplantagoin the conventional system could be as a unique species and its absence in the organic system, attributable to duck existence in it. Based on life-cycle, 6 species were annual and 4 were perennial. While, according to the photosynthetic pathway, 50 percent species were C3 and others had C4 pathway. Based on the characteristics of the interference, 4 species were noxious and 6 species were non-noxious. Poaceae were the most diversity of weeds in monocotyledon and C4 pathway (three species. Two species of noxious weeds and herbicide resistant belong to Poaceae too. The Cyperaceae consist of two species from four perennial ones. The weeds of Poaceae and Cyperaceae families include 70% of total weed. Generally, weeds in ecosystems usually change thehabitat conditions or impact on the resources availability for other species. Conclusions Due to repeated or severe disturbances, agro-ecosystems are limited to the early stages of succession. Thus, the widespread destruction of agro-ecosystems during consecutive years, by changing the succession, weed population dynamics was affected as well. It should be noted that the differences of weed distribution in the various stages

Control of ALS resistant volunteer oil seed rape and other dicotyledonous weeds with GF-145, a new cereal herbicide product containing isoxaben and florasulam

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Becker, Jörg

2014-02-01

Full Text Available GF-145 contains the active ingredients isoxaben (610 g ai/kg and florasulam (40 g ai/kg and is formulated as a Wettable Granule (WG. The active ingredients are found in commercial products such as Primus™2 (florasulam, Starane XL™ (fluroxypyr + florasulam, Ariane C™ (fluroxypyr + florasulam + clopyralid or Flexidor™ (isoxaben. While florasulam has been widely used in cereal crops in recent years, isoxaben offers a new mode of action (MOA for use in German cereal herbicides even when considering that Flexidor™ has had regulatory approval in 1988 to 1991. The MOA of isoxaben is inhibition of cellulose synthesis (HRAC class L, while florasulam inhibits Acetolactate Synthase (ALS and is a representative of the HRAC class B. It is known that florasulam works through uptake by green leaves. Isoxaben is a herbicide with soil activity and with a very low activity when foliar applied, except on some species in the cruciferae family. GF-145 is intended to be applied in the autumn in cereals (wheat, barley, rye, triticale for the control of ALS resistant volunteer oil seed rape and annual dicotyledonous weeds including Matricaria spp., Stellaria media, Papaver rhoeas, Capsella bursa-pastoris, Myosotis arvensis, Lamium spp., Galium aparine, Veronica spp. and others when applied at early post-emergence from BBCH 10 to 13 of the crop. The use rate in winter cereals is 95 g product/ha (58 g ai/ha isoxaben plus 3.75 g ai/ha florasulam. Field trials conducted in previous years confirmed excellent selectivity in all cereal crops and efficacy trials initiated in autumn 2012 show that GF-145 provides excellent and superior control to ALS resistant oil seed rape that was better than straight florasulam and other ALS active ingredients. GF-145 adds a new MOA to the cereal herbicide portfolio and controls volunteer oil seed rape, cruciferous weeds and broad-leaved weeds and is more robust than florasulam based products that do not contain isoxaben.

Controls on winter ecosystem respiration in temperate and boreal ecosystems

Science.gov (United States)

T. Wang; P. Ciais; S.L. Piao; C. Ottle; P. Brender; F. Maignan; A. Arain; A. Cescatti; D. Gianelle; C. Gough; L Gu; P. Lafleur; T. Laurila; B. Marcolla; H. Margolis; L. Montagnani; E. Moors; N. Saigusa; T. Vesala; G. Wohlfahrt; C. Koven; A. Black; E. Dellwik; A. Don; D. Hollinger; A. Knohl; R. Monson; J. Munger; A. Suyker; A. Varlagin; S. Verma

2011-01-01

Winter CO2 fluxes represent an important component of the annual carbon budget in northern ecosystems. Understanding winter respiration processes and their responses to climate change is also central to our ability to assess terrestrial carbon cycle and climate feedbacks in the future. However, the factors influencing the spatial and temporal...

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

Competitive Ability of Lentil (Lens culinaris L. Cultivars to Weed Interference under Rain-fed Conditions

Directory of Open Access Journals (Sweden)

Javad Hamzei

2016-07-01

Full Text Available Introduction The lentil or masoor (Lens culinaris L. is a brushy annual plant of the legume family, grown for its lens-shaped seeds. Lentil has been one of the first crops domesticated in the Near East. With 26% protein, lentil is the vegetable with the highest level of protein other than soybeans, and it is an important part of people’s diet in many parts of the world. It is reported that the average yield of lentil is considerably low compared to its potential yield of 1500-2000 kg ha-1, obtained in the research field. Such lower yield may be attributed to the poor management of the crop among which poor weed management is an important one. Lentil crop is not very competitive against weeds due to small and weak canopy. Weed reduces yield through competition with crop plants for space, moisture, light and plant nutrients. Generally 20 to 30% losses of grain yield are quite usual and may increase even 50%, if the crop management practices are not properly followed (Deihimfard et al., 2007. The modern lentil varieties give good yield if the land remains weed free for the first one month. However, most of the farmers are reluctant to control weeds in lentil field timely and finally, loses yield. Inadequate weed control was found to reduce the yield 40-66% in lentil (Erman et al., 2008; McDonald et al., 2007. A major component of integrated weed management is the use of more competitive crops, although the selection of better crop competitiveness is a difficult task. The use of competitive plants for weed control could be considered cost-effective and less labour-intensive, and thus reduces the amount of herbicides required. Therefore, the aim of this research was to evaluate lentil competitive ability and to compare the effects of cultivar selection. Materials and methods An experiment was carried out as a factorial based on a randomized complete block design (RCBD with 10 treatments and three replications. Experimental treatments included hand

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.

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

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%.

Produtividade de feijão-guará e efeito supressivo de culturas de cobertura de inverno em espontâneas de verão = Common bean yield and the suppressive effect of winter cover crops on summer weeds

Directory of Open Access Journals (Sweden)

Henrique von Hertwig Bittencourt

2009-10-01

Full Text Available Investigou-se o efeito das coberturas de inverno centeio, aveia, azevém, ervilhaca e nabo forrageiro (e suas associações, em sistema de plantio direto, sobre a cobertura do solo e a produção de biomassa das coberturas de inverno, sobre a biomassa de plantas espontâneas deverão, no período crítico de competição, e sobre a produtividade do feijão, cv Guará. O experimento foi instalado em delineamento experimental constituído por blocos ao acaso com quatro repetições. Observaram-se as maiores percentagens de cobertura do solo no inverno, com os tratamentos centeio + ervilhaca, centeio + ervilhaca + nabo forrageiro e aveia + ervilhaca; a produção de biomassa de cobertura foi maior com centeio + ervilhaca + nabo forrageiro. Oefeito de supressão observado foi maior no monocultivo de azevém e no consórcio de centeio + ervilhaca + nabo forrageiro, porém não foi detectada correlação da biomassa de cobertura com a supressão de plantas espontâneas de verão. Os melhores rendimentos de feijão foram obtidos com o monocultivo de azevém, monocultivo de aveia e combinação centeio + ervilhaca, que atingiram 1.950, 1.730 e 1.790 kg ha-1, respectivamente. O azevém e a aveia em monocultivo apresentaram os menores custos com sementes e as maiores receitas, ou seja, os maiores retornos por unidade monetária investida.The effect of the winter cover crops rye, oat, ryegrass, vetch and fodder radish (and their mixtures in no-tillage systems was investigated on soil cover, cover crop biomass and summer weed biomass during the critical competition stage with common bean. Bean yield was also evaluated. The experimental design was randomized complete blocks and four repetitions. The highest soil cover during winter was observed in the treatments rye + vetch, rye + vetch +fodder radish and oat + vetch. The highest values of cover crops biomass production were observed in the treatments rye + vetch + fodder radish. Weed suppression was higher

Effects Of Spring Herbicide Treatments On Winter Wheat Growth And Grain Yield*

Directory of Open Access Journals (Sweden)

Hamouz P.

2015-03-01

Full Text Available Herbicides provide a low-cost solution for protecting crops from significant yield losses. If weed infestations are below damage thresholds, however, then herbicide application is unnecessary and can even lead to yield loss. A small-plot field trial was conducted to examine the effect of herbicides on winter wheat yields. Weeds were removed manually from the trial area before herbicide application. Twenty-four treatments were tested in four replications. Treatment 1 consisted of an untreated weed-free control, whereas the other treatments comprised applications of the following herbicides and their combinations: metsulfuron-methyl + tribenuron-methyl (4.95 + 9.99 g ha−1, pinoxaden (30 g ha−1, fluroxypyr (175 g ha−1, and clopyralid (120 g ha−1. Water (250 l ha−1 or a urea-ammonium nitrate fertilizer solution (UAN, 120.5 l ha−1 was used as the herbicide carrier. Crop injury 30 days after treatment and yield loss were recorded. Results showed minor crop injury by herbicides and their combinations when applied without UAN and moderate injury caused by UAN in combination with herbicides. Yield losses reached 5.3% and 4.3% in those treatments where all of the tested herbicides were applied with and without UAN, respectively. The effect of all treatments on crop yield was, however, statistically insignificant (P = 0.934.

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...

Factors affecting Bromus tectorum seed bank carryover in western Utah

Science.gov (United States)

Duane C. Smith; Susan E. Meyer; V. J. Anderson

2008-01-01

Cheatgrass (Bromus tectorum L.) is a winter annual weed that presents a serious obstacle to rangeland restoration in the Intermountain West. The objective of this study was to evaluate factors regulating the size and persistence of cheatgrass carryover seed banks on semiarid sites in western Utah. We prevented current-year seed production in each of...

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...

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

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.

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.

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.

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...

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 ...

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.

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...

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,

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 ...

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.

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.

Evaluation of weed control methods on sugar beet (Beta vulgaris L. yield at different levels of nitrogen

Directory of Open Access Journals (Sweden)

AliAsghar Chitband

2017-03-01

Full Text Available Introduction: Weed competition is one of the major factors which limit sugar beet production in the world. Weed – crop interactions are based on competition for water, nutrients and light and allelopathic effects may also play a small role. In sugar beet weed interference, all these factors are important too, but the light is of prime importance. Due to the fact that a lot of weeds can grow above the sugar beet canopy and reduce the amount of photosynthetic radiation reaching the crop, these weeds are stronger competitors compared to smaller weeds. In much sugar beet growing areas dicot weeds of the families Chenopodiaceae, Asteraceae, Brassicaceae and Polygonaceae are of major importance. The monocots are less important compared to dicot weeds. Competition from uncontrolled annual weeds that emerge within 8 weeks of sowing or within 4 weeks of the crop reaching the two-leaf stage can reduce root yields by 26–100% .Weeds that emerge 8 weeks after sowing, and particularly after the sugar beet plants have eight or more leaves, are less likely to affect yield. Although tractor hoeing and hand labour are still used in many production areas, herbicides have been the primary method of weed control in sugar beet. The effectiveness of pre-emergence residual herbicides decreases with reductions in rainfall or soil wet content. Therefore, less than 10 % of the total sugar beet crop is treated with pre-emergence herbicides. The remaining 90 % depends solely on a selection of post-emergence herbicides to maintain season-long weed control. The major herbicides are phenmedipham, chloridazon, metamitron. Mixtures of post-emergence, broad spectrum herbicides have to be applied to control the wide range of weed species in sugar beet crops. Materials and Methods: To study the effects of weeds control by hand weeding and herbicides combination with two selective herbicides at different levels of nitrogen application on sugar beet yield and quality

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

Evaluation of multi-species weed competition and weeds population dynamic in corn Zea mays L. field

Directory of Open Access Journals (Sweden)

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.

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 ...

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

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.

Water management as a key component of integrated weed management

Directory of Open Access Journals (Sweden)

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.

Nitrogen and carbohydrate fractions in exclusive Tifton 85 and in pasture oversown with annual winter forage species - 10.4025/actascianimsci.v34i1.11428

Directory of Open Access Journals (Sweden)

Ana Claudia Ruggieri

2011-11-01

Full Text Available The experiment was undertaken at the Faculty of Agrarian and Veterinary Sciences (FCAV Jaboticabal, São Paulo State, Brazil, during winter-spring-summer of 2001-2002, to determine the fractionation of nitrogen and carbohydrates in Tifton 85 (Cynodon dactylon Vanderyst x Cynodon nlemfuensis (L. Pers, exclusively or oversown with winter annual forage species. Treatments comprised bristle oat (Avena strigosa Schreb, yellow oat (Avena byzantina C. Koch, triticale (X Triticosecale Wittmack, bristle oat + yellow oat, bristle oat + triticale, yellow oat + triticale, bristle oat + yellow oat + triticale seeded in Tifton 85 and sole crop (control. Experimental design was composed of completely randomized blocks with three replications. Fodder was cut 20 cm high (presence of winter forage and 10 cm high (Tifton 85 pasture. Crude protein, total carbohydrate and the fractions of nitrogen compounds and carbohydrates were determined. Decrease was reported in the levels of chemical compounds in winter forage species and in Tifton 85 during the evaluation periods. The content of nitrogen compounds and carbohydrates varied widely during the evaluation period according to the morphological characteristics of grass species and botanical composition of pastures.

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.

Weeds and ground-dwelling predators' response to two different weed management systems in glyphosate-tolerant cotton: A farm-scale study.

Science.gov (United States)

García-Ruiz, Esteban; Loureiro, Íñigo; Farinós, Gema P; Gómez, Pablo; Gutiérrez, Elena; Sánchez, Francisco Javier; Escorial, María Concepción; Ortego, Félix; Chueca, María Cristina; Castañera, Pedro

2018-01-01

The use of glyphosate, as a post-emergence broad-spectrum herbicide in genetically modified glyphosate-tolerant (GT) cotton, supposes a big change in weed management programs with respect to a conventional regime. Thus, alterations in arable flora and arthropod fauna must be considered when evaluating their potential impacts. A 3-year farm-scale study was conducted in a 2-ha GT cotton crop, in southern Spain, to compare the effects of conventional and glyphosate herbicide regimes on weed abundance and diversity and their consequences for ground-dwelling predators. Surveys reveal that weed density was relatively low within all treatments with a few dominant species, with significantly higher weed densities and modifications of the floristic composition in glyphosate-treated plots that led to an increase in the abundance of Portulaca oleracea and to a reduction in plant diversity. The activity-density of the main predatory arthropod taxa (spiders, ground beetles, rove beetles and earwigs) varied among years, but no significant differences were obtained between conventional and glyphosate herbicide regimes. However, significant differences between treatments were obtained for ground beetles species richness and diversity, being higher under the glyphosate herbicide regime, and a positive correlation with weed density could be established for both parameters. The implications of these findings to weed control in GT cotton are discussed.

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

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)

Titan's Emergence from Winter

Science.gov (United States)

Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

2011-01-01

We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

Activity, Density, and Weed Seed Predation Potential of Ground Beetles in Annual Row Crops of the Pacific Northwest

Science.gov (United States)

Regulation of weed seed banks in agricultural systems involves management of seed input from seed rain, and seed removal from mortality and germination. While seed rain, germination, and emergence are managed using a number of methods such as tillage and herbicides, management of seed mortality is f...

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...

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...

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

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

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....

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.

Weeds and ground-dwelling predators′ response to two different weed management systems in glyphosate-tolerant cotton: A farm-scale study

Science.gov (United States)

Farinós, Gema P.; Gómez, Pablo; Gutiérrez, Elena; Sánchez, Francisco Javier; Escorial, María Concepción; Ortego, Félix; Chueca, María Cristina; Castañera, Pedro

2018-01-01

The use of glyphosate, as a post-emergence broad-spectrum herbicide in genetically modified glyphosate-tolerant (GT) cotton, supposes a big change in weed management programs with respect to a conventional regime. Thus, alterations in arable flora and arthropod fauna must be considered when evaluating their potential impacts. A 3-year farm-scale study was conducted in a 2-ha GT cotton crop, in southern Spain, to compare the effects of conventional and glyphosate herbicide regimes on weed abundance and diversity and their consequences for ground-dwelling predators. Surveys reveal that weed density was relatively low within all treatments with a few dominant species, with significantly higher weed densities and modifications of the floristic composition in glyphosate-treated plots that led to an increase in the abundance of Portulaca oleracea and to a reduction in plant diversity. The activity-density of the main predatory arthropod taxa (spiders, ground beetles, rove beetles and earwigs) varied among years, but no significant differences were obtained between conventional and glyphosate herbicide regimes. However, significant differences between treatments were obtained for ground beetles species richness and diversity, being higher under the glyphosate herbicide regime, and a positive correlation with weed density could be established for both parameters. The implications of these findings to weed control in GT cotton are discussed. PMID:29351549

Cool-season annual pastures with clovers to supplement wintering beef cows nursing calves

Directory of Open Access Journals (Sweden)

Gunter Stacey A

2012-07-01

Full Text Available Abstract In December of 3 years, 87 beef cows with nursing calves (594 ± 9.8 kg; calving season, September to November at side were stratified by body condition score, body weight, cow age, and calf gender and divided randomly into 6 groups assigned to 1 of 6 cool-season annual pastures (0.45 ha/cow that had been interseeded into a dormant common bermudagrass (Cynodon dactylon [L.] Pers./bahiagrass (Paspalum notatum Flugge sod. Pastures contained 1 of the following 3 seeding mixtures (2 pastures/mixture: 1 wheat (Triticum aestivum L. and ryegrass (Lolium multiflorum Lam., WRG, 2 wheat and ryegrass plus red clover (Trifolium pretense L., WRR, or 3 wheat and ryegrass plus white (Trifolium repens L. and crimson clovers (Trifolium incarnatum L., WRW. All groups had ad libitum access to grass hay (12% crude protein; 58% total digestible nutrients. The second week in December, cow estrous cycles were synchronized and artificially inseminated. In late December, a bull was placed with each group for 60-d. Data were analyzed with an analysis of variance using a mixed model containing treatment as the fixed effect and year as the random effect. Body weight and condition scores did not differ (P ≥ 0.27 among cows between February and June. Calf birth weights or average daily gain did not differ (P ≥ 0.17 among treatments; however, calves grazing pastures with clovers did tend (P = 0.06 to weigh more than calves grazing grass only. Weaning weight per cow exposed to a bull was greater (P = 0.02 for WRR and WRW than WRG. Cows grazing winter-annual pastures containing clovers tended to wean more calf body weight per cow exposed to a bull than cows grazing the grass only pastures.

Weed vegetation ecology of arable land in Salalah, Southern Oman.

Science.gov (United States)

El-Sheikh, Mohamed A

2013-07-01

This paper applies multivariate statistical methods to a data set of weed relevés from arable fields in two different habitat types of coastal and mountainous escarpments in Southern Oman. The objectives were to test the effect of environmental gradients, crop plants and time on weed species composition, to rank the importance of these particular factors, and to describe the patterns of species composition and diversity associated with these factors. Through the application of TWINSPAN, DCA and CCA programs on data relating to 102 species recorded in 28 plots and farms distributed in the study area, six plant communities were identified: I- Dichanthium micranthum, II- Cynodon dactylon-D. micranthum, III- Convolvulus arvensis, IV- C. dactylon-Sonchus oleraceus, V- Amaranthus viridis and VI- Suaeda aegyptiaca-Achyranthes aspera. The ordination process (CCA) provided a sequence of plant communities and species diversity that correlated with some anthropogenic factors, physiographic variables and crop types. Therefore, length of time since farm construction, disturbance levels and altitude are the most important factors related to the occurrence of the species. The perennial species correlated with the more degraded mountain areas of new farm stands, whereas most of the annuals correlated with old lowland and less disturbed farms.

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.

Winter Video Series Coming in January | Poster

Science.gov (United States)

The Scientific Library’s annual Summer Video Series was so successful that it will be offering a new Winter Video Series beginning in January. For this inaugural event, the staff is showing the eight-part series from National Geographic titled “American Genius.” 

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.

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.

Mapping the Distribution and Flora of the Weeds in Canola Fields of Gorgan Township by Geographic Information System (GIS

Directory of Open Access Journals (Sweden)

sahar jannati ataie

2018-02-01

species in canola fields of Gorgan Township and these belonged to 18 families. About 17.1 percent of these species belong to Poaceae and 11.4 percent belongs to Asteraceae and other families, respectively. In general, 77.2 and 22.8 percent of species were annual and perennial weeds, respectively. Also, 80 percent of weeds belong to dicotyledonous and 20 percent to monocotyledonous. The most important species of Poaceae family were Phalaris minor, Avena ludoviciana, Alopecuros sp., Poa annua, Lolium temulentum and Bromus sp. Also, the most important species of Asteraceae were Artemisia annua, Cirsium arvense, Sonchus sp. and Senecio vulgaris. 85.7 percent of weeds reported as broad-leaved weeds and 14.3 percent belong to the narrow leaves. Phalaris minor was the most important weed of narrow leaves and Melilotus officinalis was the most important broad leaf out groups. Among the weeds have been identified, 88.5 percent had photosynthetic cycle of C3 and 11.5 percent were C4. The study results also showed that Phalaris minor had the highest relative dominance among the 35 species and then Melilotus officinalis, Rapistrum rugosum and Avena ludoviciana had 29.4, 28.9 and 23.5 of relative dominance, respectively. To view maps of distribution, based on the abundance of weeds, the three categories 50-100 percent, 30-50 percent and lower than 30 percent were classified. Weeds that have had 50-100 percent frequency were considered as the most important weeds in canola fields of Gorgan. These weeds includes: Phalaris minor and Melilotus officinalis. Weeds that have a frequency between 30-50 percent were considered as medium importance weeds that included Sinapis arvensis, Veronica persica, Avena ludoviciana and Rapistrum rugosum. In final, the weeds with a frequency of less than 30 percent, were placed in the third group as small percentage of surveyed fields. The most important weeds in this group recorded as Artemisia annua, Ranunculus sp., Polygonum convolvulus and Alopecuros sp

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

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 ,