Showing papers on "Weed control published in 2007"
TL;DR: The relatively rapid emergence of “weedy” rice, rice phenotypically similar to cultivars but exhibiting undesirable agronomic traits, has been observed in several Asian countries practicing DSR, and this poses a severe threat to the sustainability of the production system.
Abstract: Rice ( Oryza sativa L.) is a principal source of food for more than half of the world population, especially in South and Southeast Asia and Latin America. Elsewhere, it represents a high‐value commodity crop. Change in the method of crop establishment from traditional manual transplanting of seedlings to direct‐seeding has occurred in many Asian countries in the last two decades in response to rising production costs, especially for labor and water. Direct‐seeding of rice (DSR) may involve sowing pregerminated seed onto a puddled soil surface (wet‐seeding) or into shallow standing water (water‐seeding), or dry seed into a prepared seedbed (dry‐seeding). In Europe, Australia, and the United States, direct‐seeding is highly mechanized. The risk of crop yield loss due to competition from weeds by all seeding methods is higher than for transplanted rice because of the absence of the size differential between the crop and weeds and the suppressive effect of standing water on weed growth at crop establishment. Of 1800 species reported as weeds of rice, those of the Cyperaceae and Poaceae are predominant. The adoption of direct‐seeding has resulted in a change in the relative abundance of weed species in rice crops. In particular, Echinochloa spp., Ischaemum rugosum, Cyperus difformis , and Fimbristylis miliacea are widely adapted to conditions of DSR. Species exhibit variability in germination and establishment response to the water regime postsowing, which is a major factor in interspecifically selecting constituents of the weed flora. The relatively rapid emergence of “weedy” (red) rice, rice phenotypically similar to cultivars but exhibiting undesirable agronomic traits, has been observed in several Asian countries practicing DSR, and this poses a severe threat to the sustainability of the production system. Stale seedbeds, tillage practices for land leveling, choice of competitive rice cultivars, mechanical weeders, herbicides, and associated water management are component technologies essential to the control of weeds in DSR. Herbicides in particular are an important tool of weed management, but hand weeding is either partially or extensively practiced in countries of Asia, Africa, and Latin America. Though yet to be globally commercialized, transgenic rice varieties engineered for herbicide resistance are a potential means of weed control. The release of herbicide‐resistant rice for red rice control in the United States has indicated the need to critically examine mitigation methods for the control of gene flow. Integrating preventive and interventional methods of weed control remains essential in managing weed communities in DSR, both to prohibit the evolution of herbicide resistance and to maximize the relative contributions of individual components where herbicides are not widely used. There remains a need to further develop understanding of the mechanisms and dynamics of rice weed competition and of the community dynamics of weed populations in DSR to underpin sustainable weed management practices.
954 citations
TL;DR: The vast majority of crop hectares in the United States are treated with chemical herbicides annually as discussed by the authors, and the use of herbicides has been widely accepted as a cost effective method for weed control.
Abstract: The vast majority of crop hectares in the United States are treated with chemical herbicides annually. The adoption of herbicides for weed control was rapid in the 1950s and 1960s. Herbicides replaced the use of millions of workers to pull and hoe weeds by hand and greatly reduced the use of tillage for weed control. Costs of production were reduced and crop yields increased because herbicides were cheaper and more effective than hand weeding and cultivation. Organic crop growers cite weed control as their greatest difficulty in crop production because they are not permitted the use of chemical herbicides. They substitute hand weeding and cultivation for herbicides at a greatly increased cost and with reduced effectiveness. Aggregate studies that estimate the value of herbicides assume that growers would substitute a certain amount of hand weeding and tillage if chemicals were not used, which would not be sufficient to prevent yield losses totaling about 20% of U.S. crop production.
251 citations
TL;DR: It is concluded that application of wheat residue mulch at 4 t ha –1 and Sesbania intercropping for 30 days were equally effective in controlling weeds associated with dry-seeded rice and resulting in higher net returns than the weed-free treatment.
218 citations
1 Jan 2007
205 citations
TL;DR: In this paper, a review of the current knowledge of weeds and weed control methods on hard surface areas and reveal potential ways of advancement is presented. But, the focus of this review is on arable land and not on hard surfaces.
Abstract: Summary Weed control research to date has mainly focused on arable land, especially regarding herbicides, but also regarding non-chemical methods. Some of these experiences can be applied to hard surface areas. However, weeds on hard surface areas cause problems that are different from those on arable land. Additionally, crop tolerance does not need to be considered when choosing an appropriate weed control method on these areas. The aim of this review is to describe current knowledge of weeds and weed control methods on hard surface areas and reveal potential ways of advancement. One of the shortcomings of non-chemical weed control on hard surfaces thus far, is a lack of proper definition of efficiency of the weed control methods. To obtain effective control, more frequently repeated treatments are required than chemical weed management, thereby increasing the costs of labour and fuel. One way to reduce costs can be by adjusting the level of control to the required visual street quality. Weeds are adapted to the hard surface environment and may be less susceptible to certain control methods. This review indicates that for efficient weed control on hard surfaces there is a need for combining weed control techniques, applying sensors for detecting weeds, adapting the energy dose to type of weed flora and prevention of weeds by improved construction of new surfaces.
105 citations
TL;DR: The present study suggests that combining a weed-suppressive genotype with an optimum seeding rate can serve as a tool to manage weeds.
86 citations
TL;DR: Field studies showed that enhancing crop competitiveness through planting competitive varieties at relatively high seeding rates and through strategic fertilizer placement including sub-surface banded or point-injected nitrogen can reduce the impact of weeds on crop yield and the amount of weed seed entering the soil seed bank.
86 citations
TL;DR: Mulch of A. indica, a medicinal plant, holds good promise for use as a natural herbicide for managing weeds in wheat fields and enhancement in the grain yield of wheat and suppression of weeds under natural field conditions is concluded.
77 citations
TL;DR: Repeated meal applications of Brassica napus, Brassica juncea and Sinapis alba did provide early season weed control in both years and inhibition of crop emergence appears to be highly dependent on the amount and distribution of water.
Abstract: Brassicaceae seed meals produced through the oil extraction process release biologically active glucosinolate secondary products and may be useful as a part of biological weed control systems. Before meal can be used most efficiently, recommendations for suitable planting dates that maximize weed control but reduce crop injury must be determined. Our objectives were to determine the impact of 1 and 3% (w/w) meal applications of Brassica napus L. (canola), Brassica juncea L. (oriental mustard) and Sinapis alba L. (yellow mustard) on crop emergence and weed biomass in a growth chamber and field study. Results from the growth chamber experiment indicated that lettuce emergence was reduced by at least 75% when planted into 3% S. alba-amended soil earlier than 5 weeks after meal application. After 5 weeks, emergence was not different among treatments. Crop emergence was not reduced by any meal treatment as compared to the no-meal treatment in year 1 of the field study. In year 2, crop emergence in each 1.2-m row was inhibited by all meal treatments and ranged from 16 plants in the 3% B. juncea treatment to 81 plants in the no-meal treatment. The difference between emergence results in year 1 and year 2 is likely due to differing climatic conditions early in the season prior to irrigation, and the method of irrigation used. Redroot pigweed (Amaranthus retroflexus L.) biomass was 72–93% lower in 1% B. juncea and 3% treatments relative to the no-meal control in the first weed harvest of year 1. These same treatments had 87–99% less common lambsquarters (Chenopodium album L.) biomass. By the second weed harvest, redroot pigweed biomass in meal treatments (0.02–1.6 g m−2) was not different from that in the no-meal treatment (0.97 g m−2). Redroot pigweed biomass in 3% B. juncea plots was reduced by 74% relative to the no-meal treatment in the first harvest of year 2. This treatment also reduced common chickweed [Stellaria media (L.) Vill.] biomass by 99% relative to the 1% meal treatments. While pigweed biomass was reduced by 3% B. juncea in the early part of the season, by the second harvest this same treatment had the greatest pigweed biomass. Despite significant variability between years, 3% B. juncea did provide early season weed control in both years. Repeated meal applications, however, may be necessary to control late season weeds. Inhibition of crop emergence appears to be highly dependent on the amount and distribution of water and needs to be further studied in field settings.
75 citations
TL;DR: In this paper, the authors test the hypothesis that weed seed mortality due to microbial predation is limited by soil inorganic N availability and soil C:N ratio and find that weed seeds are rich in carbon and nitrogen, and therefore may represent an important nutritional resource to soil microbes.
Abstract: Weed seed persistence in the soil seedbank is central to weed population dynamics; however, limited knowledge of mechanisms regulating seed survival in soil remains an obstacle to developing seed-bank management practices. Weed seeds are rich in carbon and nitrogen, and therefore may represent an important nutritional resource to soil microbes. The objective of this study was to test the hypothesis that weed seed mortality due to microbial predation is limited by soil inorganic N availability and soil C:N ratio. A factorial of N fertilizer rate (0, 14, and 28 mg N kg soil−1) and corn stover addition rate (0 and 3,000 mg stover kg soil−1) was applied to bioassay units containing Illinois field soil (silt loam, 3.8% organic carbon) and seeds of one of eight annual weed species common to Illinois field crops: giant foxtail, green foxtail, yellow foxtail, wooly cupgrass, giant ragweed, redroot pigweed, velvetleaf, and Venice mallow. Seeds were incubated for 2 mo, after which they were recovered from ...
70 citations
Journal Article•
TL;DR: Effective and economical weed control methods include preand post-em herbicides along with one hand weeding was found effective in controlling weeds and producing higher paddy yield.
Abstract: Dry seeding of rice (Oryza sativa L.) involves a major change in the production practices for attaining optimal plant density and high water productivity in the waterdeficit areas of Pakistan. Weeds pose serious threat to sustainability and viability of direct seeded rice system. Information on weed management in dry seeding rice in Pakistan is lacking. A field experiment was conducted to identify appropriate, effective, and economical methods of managing weeds in dry-seeded rice. The major weeds associated with dry-seeded rice were Echinochloa crusgalli, Cyperus iria, C. difformis, Paspalum distichum, Eclipta prostrata, and Trianthema portulacastrum. Pendimethalin 750 g a.i. ha, ethoxysulfuron at 18 g a.i. ha, and 2,4-D (ester) at 500 g a.i. ha, were equally effective in realizing higher rice grain yields by controlling broad leaf weeds and sedges. Among these, 2,4-D (ester) at 18 g a.i. ha was found to be least expensive but effective for controlling broad leaf weeds. Effective and economical weed control methods include preand post-em herbicides along with one hand weeding was found effective in controlling weeds and producing higher paddy yield.
TL;DR: Application of nicosulfuron at 80 g ai/ha resulted in the highest maize yield after the weed-free check, however, 2,4-D plus MCPA plots had the lowest grain yield among all treatments.
Patent•
6 Jun 2007TL;DR: In this paper, it was found that pre-emergent applications of dicamba at or near planting could be made without significant crop damage or yield loss, and the techniques can be combined with the herbicide glyphosate to improve the degree of weed control and permit control of herbicide tolerant weeds.
Abstract: The invention provides methods for weed control with dicamba and related herbicides. It was found that pre-emergent applications of dicamba at or near planting could be made without significant crop damage or yield loss. The techniques can be combined with the herbicide glyphosate to improve the degree of weed control and permit control of herbicide tolerant weeds.
TL;DR: Flaming compared favorably with control attainable with herbicides, but control was more variable and sensitive to environmental conditions than generally expected of herbicides.
TL;DR: In this paper, the effects of three different weed management strategies on the required input of hand weeding in an arable organic farming system, the weed seedbank in the soil and the emerging weed seedling emergence were studied from 1996 to 2003.
Abstract: Summary The effects of three different weed management strategies on the required input of hand weeding in an arable organic farming system, the weed seedbank in the soil and the emerging weed seedling emergence were studied from 1996 to 2003. Strategies were based on population dynamic models and aimed for (1) control of weeds as carried out in standard organic farming practice, (2) control of all residual weeds that grow above the crop and (3) prevention of all weed seed return to the soil. Under all strategies, the size of the seedbank increased during the conversion from conventional to organic farming systems. The increase under strategy 3 was significantly smaller than the increase under the other strategies. From 1999 onwards, the weed densities in plots treated with strategy 3 became significantly lower than the weed densities in plots treated with the other strategies. The time needed for hand-weeding required to prevent weed seed return, in addition to the time needed in standard organic farming practices, reduced during the course of the study. A management strategy aimed at the prevention of seed return (strategy 3) can reduce the size of the increase of the seedbank, which is usually observed after transition from conventional to organic farming. This study provides unique real-world data that are essential for evaluating population dynamic models. The results may contribute to the development of weed management systems based on no seed threshold strategies and to a further decrease in the dependence on herbicides.
TL;DR: In this article, the authors used Landsat data from the Yaqui Valley, a prominent spring wheat growing region in Northwest Mexico, to investigate the effect of planting date and fallow period weeds on wheat yields.
TL;DR: In this article, the authors broadly review various preventive and curative non-chemical weed management tactics and demonstrate how innovations can be derived from functional requirements of weed management operations, and from biological processes and weaknesses in weed's lifecycles.
Abstract: 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, particularly in no-till systems. Herbicides are an exhaustible resource, so new approaches to merge soil conservation and non-chemical weed management are needed. This paper broadly reviews various preventive and curative non-chemical weed management tactics. It also demonstrates how innovations can be derived from functional requirements of weed management operations, and from biological processes and weaknesses in weed's lifecycles. Mechanical weeding and enhancement of weed seed mortality are highlighted as examples. Major limitations with mechanical weeding include limited weed control in crop rows at early vulnerable crop stages, weather-dependent effectiveness, and difficulties in handling crop residues. Precise steering and depth control, improved seedbed friability and lighter tractors or controlled traffic could bring considerable improvements. To expose weed seeds to predators, position them for fatal germination, viability loss or low emergence may require completely different soil displacement patterns than those of current implements and systems. Controlled traffic and precise strip tillage offer good opportunities for implementing these weed management strategies in minimum-tillage systems.
TL;DR: Using lower doses than recommended this herbicide controls the annual grass weeds better than some broad-leaved weeds and at the later application date the lower herbicide dose seems to require a lower application volume to provide maximum grain yield.
TL;DR: Late weed emergence was the main reason of weed escapes with one-pass glyphosate, and Chenopodium album showed a long period of emergence, thereby allowing the late-emerging cohorts to avoid contact with the herbicide.
TL;DR: In this paper, the effect of mulching applied to mandarin tree rows for weed control in two localities near Tortosa, Spain, to compare its performance with the present chemical weed control system using the herbicide glyphosate.
Abstract: Moving towards sustainable agriculture implies exploring the interconnections between farming and the environment, and soil is a key component of sustainability. Mulching is one of the methods to protect and enhance the productivity of the soil. We studied here the effect of mulching applied to mandarin tree rows for weed control in two localities near Tortosa, Spain, to compare its performance with the present chemical weed control system using the herbicide glyphosate. Three mulches were tested in each citrus orchard: rice straw, almond husk and black geotextile. Five plots per treatment, that is, three mulches, glyphosate application and control, were arranged following a randomized block design. Each plot was five trees long and its width was the distance between the two drip-lines. Just before mulch installation, bags containing non-dormant seeds of Amaranthus retroflexus and Diplotaxis erucoides were buried at three depths, and were exhumed one year later. After exhumation, sets of 250 seeds were placed in incubators and cumulative germination was obtained. Moreover, the weed flora was monitored at the two localities on four dates over one year and its total cover was evaluated. Seeds of A. retroflexus and D. erucoides showed the highest germination below almond husk, 90.9% and 96.2%, respectively. In total 74 species were recorded covering the mandarin tree rows. Our results indicated that black geotextile and almond husk controlled the presence of weeds as well as or better than the applications of glyphosate at least during the first year after their introduction. No significant differences were found between the mean weed cover of black geotextile (0.88%), almond husk (4.04%) and herbicide plots (2.04%). Altogether, our results show that mulching is one weed control strategy in mandarin orchards that also provides other benefits in terms of sustainable agriculture, such as soil protection or avoiding herbicide pollution.
TL;DR: A weed infestation survey was performed in 20 second corn crop areas in 1997 and in 40 areas in 1998 and 1999 after soybean planting in the Medio Paranapanema Region, Sao Paulo, showing a strong infestation increase of C. echinatus, which turned out to be the most important weed species in the area evaluated.
Abstract: A weed infestation survey was performed in 20 second corn crop areas in 1997 and in 40 areas in 1998 and 1999 after soybean planting in the Medio Paranapanema Region, Sao Paulo. The survey was conducted in the counties of Assis, Campos Novos, Cândido Mota, Cruzalia, Florinea, Maracai, Palmital, Pedrinhas Paulista and Platina. When the corn reached the grain filling stage, the crop weeds were evaluated by zigzag walking through the areas starting from different points to represent the whole area. The crops were classified in three types, according to the system applied: no-tillage, conventional system with disc plowing, and second corn crop in the soybean straw only. Infestation level and occurring weed species were evaluated in each crop. The weed control systems adopted were also considered, according to the herbicides applied. The most important weed species occurring in the areas were: Cenchrus echinatus, Bidens pilosa, Euphorbia heterophylla, Raphanus sativus, Digitaria horizontalis, Commelina benghalensis, Amaranthus sp., Achyrocline satureioides, Sinapis arvensis, Sida sp., Glycine max, Avena strigosa, Eleusina indica and Sorghum halepense. The results showed a strong infestation increase of C. echinatus, which turned out to be the most important weed species in the area evaluated. R. sativus was also important and showed an expressive increase from 1997 to 1999. Weed infestations were higher in the conventional system areas, showing that this system is inferior to the others, concerning weed control. The chemical weed control most used was the mixture of (atrazine+oil) plus 2,4-D, followed by (atrazine+oil) and atrazine alone. No weed control was used in 22% of the crops, which were the most infested. The infestation level varied from year to year for the different weed control systems, depending on climate conditions.
TL;DR: Glyphosate and glufosinate provided similar levels of control for most weed species and were often more efficacious than MSMA alone and Weed control was not improved with the addition of MSMA to glyphosate or glufoinate when compared with either herbicide alone.
Abstract: Field and greenhouse studies were conducted to investigate the compatibility of MSMA in a tank mixture with glyphosate or glufosinate for broadleaf and grass weed control. Glyphosate, glufosinate, and MSMA were evaluated at 0.5×, 1×, and 2× rates, with 1× rates of 0.84 kg ae/ha, 0.5 kg ai/ha, and 2.2 kg ai/ha, respectively. Glyphosate and glufosinate provided similar levels of control for most weed species and were often more efficacious than MSMA alone. Glyphosate controlled Palmer amaranth better than glufosinate. Glufosinate controlled hemp sesbania, pitted morningglory, and ivyleaf morningglory better than glyphosate at one location. Weed control was not improved with the addition of MSMA to glyphosate or glufosinate when compared with either herbicide alone. MSMA antagonized glyphosate efficacy on barnyardgrass, browntop millet, hemp sesbania, Palmer amaranth, and redroot pigweed. MSMA antagonized glufosinate efficacy on browntop millet, hemp sesbania, ivyleaf morningglory, johnsongrass, Palmer amara...
TL;DR: Pairing fall cultivation with glyphosate was as effective at reducing weed biomass as two glyphosate applications in 2 of 3 years, suggesting that substituting a glyphosate application with cultivation may be an effective method of reducing herbicide use in vineyards.
Abstract: Vineyard weed communities were examined under the influence of an organic weed control practice, soil cultivation with a Clemens cultivator, and applications of the herbicide glyphosate. Experimental treatments (winter–spring glyphosate, spring cultivation, fall–spring cultivation, fall cultivation–spring glyphosate) were carried out in a California wine grape vineyard for 3 yr. Cultivation alone was not as effective as glyphosate, based on lower weed biomass in the glyphosate-only treatment in 2 of 3 yr. However, given that two passes with the Clemens cultivator decreased weed biomass relative to one pass, it is possible that additional passes could bring about further reductions. Pairing fall cultivation with glyphosate was as effective at reducing weed biomass as two glyphosate applications in 2 of 3 years, suggesting that substituting a glyphosate application with cultivation may be an effective method of reducing herbicide use in vineyards. Canonical correspondence analysis revealed signific...
TL;DR: Herbicides tested performed best as they effectively controlled weeds, increased crop vigour, plant height, reduced crop injury and produced higher grain yield of sorghum.
TL;DR: Banana mulch treatment provided the best control by significantly reducing weed biomass and weed species composition and was followed by Fomesafen, coffee hulls, clear plastic mulch and Desmodium heterocarpon.
TL;DR: During the critical period of competition, the aerial biomass yield and the LAI of maize were superior to the intercropped Brachiaria brizantha .
Abstract: This study had the objective of evaluating weed control, growth and yield of intercropped maize and Brachiaria brizantha , as function of herbicide doses of nicosulfuron. Six nicosulfuron doses (0 g ha-1, 2 g ha-1, 4 g ha-1, 8 g ha-1, 16 g ha-1, and 32 g ha-1) were evaluated in a tank mixture with atrazine (1,500 g ha-1). Additionally, two weeded controls were tested represented by both species in monoculture. The weed species Brachiaria plantaginea , Sorghum arundinaceum , and Brachiaria decumbens were controlled effectively by nicosulfuron with the highest used doses. The perennial species Cyperus rotundus and Artemisia verlotorum were not controlled by the herbicides. Initially, maize presented a higher growth rate than Brachiaria brizantha causing a reduction in the biomass yield rate and the leaf area index (LAI) of the intercropped forage. This effect was increased on higher rates of nicosulfuron. The maize biomass yield was smaller in the atrazine treatment as related to those treated with the nicosulfuron + atrazine mixture and the weeded control. During the critical period of competition, the aerial biomass yield and the LAI of maize were superior to the intercropped Brachiaria brizantha . These characteristics allowed a good maize grain yield independently of the adopted management. KEY-WORDS: Crop-livestock integration; no-tillage; atrazine; nicosulfuron.
TL;DR: It is concluded that the new concept of weed management that was developed in 2002 and 2003 provides a useful framework for finding a good trade off between economical and ecological aspects of weed control on pavements.