Modeling of Glyphosate Application Timing in Glyphosate-Resistant Soybean

The introduction of herbicide-resistant crops and postemergence herbicides with a wide action spectrum shifted the research focus from how to when crops should be treated. To maximize net return of herbicide applications, the evolution of weed–crop competition over time must be considered and its effects quantified. A model for predicting the yield trend in relation to weed removal time, considering emergence dynamics and density, was tested on data from glyphosate-resistant soybean grown in cropping systems in Italy and Argentina. Despite an ample variation of weed emergence dynamics and weed load in the four trials, the model satisfactorily predicted yield loss evolution. The estimated optimum time for weed control (OTWC) varied from about 18 d after soybean emergence in Argentina to 20 to 23 d in Italy, with time windows for spraying ranging from 14 to 28 d. Within these limits a single glyphosate application ensures good weed control at low cost and avoids side effects like the more probable unfavorable weed flora evolution with double applications and the presence of residues in grains. Despite the apparent simplicity of weed control based on nonselective herbicides, the study outlines that many variables have to be considered to optimize weed management, particularly for the time evolution of the infestation and, subsequently, a proper timing of herbicide application.

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Herbicide-Resistant Canola (Brassica napus) Response and Weed Control with Postemergence Herbicides

Weed Technology ◽

10.1614/wt-05-061r.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 551-557 ◽

Cited By ~ 7

Author(s):

Timothy L. Grey ◽

Paul L. Raymer ◽

David C. Bridges

Keyword(s):

Weed Control ◽

Field Studies ◽

Italian Ryegrass ◽

Wild Radish ◽

Application Timing ◽

Herbicide Resistant ◽

Naturally Occurring ◽

And Control ◽

Postemergence Herbicides ◽

Significant Injury

Field studies were conducted to evaluate weed control in herbicide-resistant canola in Georgia. The resistant canola cultivars and respective herbicides were ‘Pioneer 45A76’ and imazamox, ‘Hyola 357RR’ and glyphosate, and ‘2573 Invigor’ and glufosinate. Weed seed of Italian ryegrass and wild radish were sown simultaneously in October with canola and control of these species was evaluated along with other naturally occurring weeds. Herbicide treatments for the respective herbicide-resistant canola cultivar were imazamox at 0.035 and 0.071 kg ai/ha, glyphosate at 0.84 and 1.64 kg ae/ha, and glufosinate at 0.5 and 1.0 kg ai/ha. Herbicides were applied at one– two-leaf (LF) and three–four-LF canola stages. There was no significant injury to any canola cultivar as a result of herbicide rate or timing of application. By midseason (February), imazamox effectively controlled wild radish, henbit, and shepherd's-purse at both rates and at both timings. When applied to three–four-LF canola, the higher rates of glyphosate and glufosinate were required to provide 75% or greater control of Italian ryegrass, wild garlic, and henbit. Glufosinate did not adequately control wild radish at either rate or application timing. Greenhouse experiments provided similar results.

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REVIEW ON WEED CONTROL IN GLYPHOSATE TOLERANT MAIZE

Reviews In Food And Agriculture ◽

10.26480/rfna.01.2021.24.26 ◽

2021 ◽

Vol 2 (1) ◽

pp. 24-26

Author(s):

Anjila Devkota ◽

Krita Karki ◽

Sijan Kafle ◽

Mina Sunar

Keyword(s):

Weed Control ◽

Weed Management ◽

Native Species ◽

Cropping Systems ◽

Plant Biotechnology ◽

Genetically Engineered ◽

Control Methods ◽

Herbicide Resistant ◽

Management Techniques ◽

Foreign Genes

Weeds are a constant nuisance for farmers, which steal space and nutrients from the crops. Weed management is the botanical component which attempts to stop noxious weeds from competing with desired flora and fauna including domesticated plants. It is preventing of non-native species competing with native species. Growth of various weeds has been major problem in the yield of many plants. It has also affected the growth and development of maize as it competes with the space and nutrients. Different weed management techniques have been introduced till date to increase the yield and to control the weeds, also, aiming less effect of the techniques on the main plant. Generally, preventive, biological, cultural, mechanical and chemical weed control methods are used. Advancements in plant biotechnology have allowed the development of a number of herbicide resistant crops which is a success in chemical weed management of the crops. They have provided the requisite tools to transform the plants to contain the foreign genes. Genetically engineered herbicide resistant crops have been widely planted globally since their introduction in 1995. These developments offer new approaches to managing weeds in cropping systems. This technology offers some advantages over currently used systems.

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Competitive ability of Australian canola (Brassica napus) genotypes for weed management

Crop and Pasture Science ◽

10.1071/cp14125 ◽

2014 ◽

Vol 65 (12) ◽

pp. 1300 ◽

Cited By ~ 23

Author(s):

Deirdre Lemerle ◽

David J. Luckett ◽

Peter Lockley ◽

Eric Koetz ◽

Hanwen Wu

Keyword(s):

Brassica Napus ◽

Grain Yield ◽

Weed Management ◽

Competitive Ability ◽

Cropping Systems ◽

Low Cost ◽

Integrated Weed Management ◽

Brassica Napus L ◽

Herbicide Resistant ◽

Weed Growth

Canola (Brassica napus L.) is an important break crop in Australian cropping systems but weeds are a major cost to production and herbicide-resistant weeds are spreading. The potential competitive ability of canola genotypes to both suppress weed growth and maintain grain yield and quality in the presence of weeds has not been determined in Australia. Two experiments examined the range in competitive ability of 16 B. napus genotypes against annual ryegrass (Lolium rigidum Gaud.) and volunteer wheat (Triticum aestivum L.) over two contrasting seasons. Weed biomass at flowering was generally reduced 50% more in the presence of the strongly competitive genotypes than the least competitive, and this has significant benefits for lower weed seed production and reduced seedbank replenishment. Suppression of weed growth was negatively correlated with crop biomass. Significant differences in grain yield of canola were recorded between weedy and weed-free plots, depending on crop genotype, presence of weeds and season. Crop yield tolerance (where 0% = no tolerance and 100% = complete tolerance) to ryegrass competition ranged from 0% (e.g. with CB-Argyle) to 30–40% (e.g. with the hybrids 46Y78 and Hyola-50) in the dry season of 2009. Yield tolerance was higher (50–100%) with the lower densities of volunteer wheat and in the 2010 season. The range between genotypes was similar for both conditions. The hybrids and AV-Garnet were higher yielding and more competitive than the triazine-tolerant cultivars. The ranking of genotypes for competitiveness was strongly influenced by seasonal conditions; some genotypes were consistently more competitive than others. Competitive crops are a low-cost tactic for integrated weed management to reduce dependence on herbicides and retard the spread of herbicide-resistant weeds.

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Herbicide-resistant crops in resistant weed management : An industrial perspective

Phytoprotection ◽

10.7202/706074ar ◽

2005 ◽

Vol 75 (4) ◽

pp. 79-84 ◽

Cited By ~ 2

Author(s):

D. Shaner

Keyword(s):

Weed Control ◽

Weed Management ◽

Wild Species ◽

Integrated Weed Management ◽

Herbicide Resistant ◽

Resistant Varieties ◽

Selection Of

Some of the first products of biotechnology to reach the marketplace have been herbicide-resistant crops. Industry sees the development of herbicide-resistant varieties as a way to increase the availability of proven herbicides for a broader range of crops. However, the development of herbicide- resistant crops requires special attention to potential environmental questions such as herbicide usage, selection of resistant weed biotypes and spread of resistance from the resistant crop to wild species. Industry is actively addressing these concerns during the process of development. Proper development and use of herbicide-resistant crops in integrated weed management programs will provide farmers with increased flexibility, efficiency, and decreased cost in their weed control practices without increasing the risk of herbicide-resistant weeds. Furthermore, herbicide-resistant crops should prove to be valuable tools in managing herbicide- resistant weeds.

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Alternatives to Atrazine for Weed Management in Processing Sweet Corn

Weed Science ◽

10.1614/ws-d-16-00001.1 ◽

2016 ◽

Vol 64 (3) ◽

pp. 531-539 ◽

Cited By ~ 3

Author(s):

Zubeyde Filiz Arslan ◽

Martin M. Williams ◽

Roger Becker ◽

Vincent A. Fritz ◽

R. Ed Peachey ◽

...

Keyword(s):

Weed Control ◽

Weed Management ◽

Sweet Corn ◽

Crop Yields ◽

Production Systems ◽

Field Trials ◽

Management Systems ◽

Weed Species ◽

Application Timing ◽

Production Areas

Atrazine has been the most widely used herbicide in North American processing sweet corn for decades; however, increased restrictions in recent years have reduced or eliminated atrazine use in certain production areas. The objective of this study was to identify the best stakeholder-derived weed management alternatives to atrazine in processing sweet corn. In field trials throughout the major production areas of processing sweet corn, including three states over 4 yr, 12 atrazine-free weed management treatments were compared to three standard atrazine-containing treatments and a weed-free check. Treatments varied with respect to herbicide mode of action, herbicide application timing, and interrow cultivation. All treatments included a PRE application of dimethenamid. No single weed species occurred across all sites; however, weeds observed in two or more sites included common lambsquarters, giant ragweed, morningglory species, velvetleaf, and wild-proso millet. Standard treatments containing both atrazine and mesotrione POST provided the most efficacious weed control among treatments and resulted in crop yields comparable to the weed-free check, thus demonstrating the value of atrazine in sweet corn production systems. Timely interrow cultivation in atrazine-free treatments did not consistently improve weed control. Only two atrazine-free treatments consistently resulted in weed control and crop yield comparable to standard treatments with atrazine POST: treatments with tembotrione POST either with or without interrow cultivation. Additional atrazine-free treatments with topramezone applied POST worked well in Oregon where small-seeded weed species were prevalent. This work demonstrates that certain atrazine-free weed management systems, based on input from the sweet corn growers and processors who would adopt this technology, are comparable in performance to standard atrazine-containing weed management systems.

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The Critical Period for Weed Control (CPWC) in Potato (Solanum tuberosum L.)

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha43210031 ◽

2015 ◽

Vol 43 (2) ◽

pp. 355-360 ◽

Cited By ~ 1

Author(s):

Dogan ISIK ◽

Adem AKCA ◽

Emine KAYA ALTOP ◽

Nihat TURSUN ◽

Husrev MENNAN

Keyword(s):

Weed Control ◽

Weed Management ◽

Critical Period ◽

Field Experiments ◽

Yield Loss ◽

Cropping Systems ◽

Control Period ◽

Relative Yield ◽

Yield Data ◽

Weed Interference

Accurate assessment of crop-weed control period is an essential part for planning an effective weed management for cropping systems. Field experiments were conducted during the seasonal growing periods of potato in 2012 and 2013 in Kayseri, Turkey to assess critical period for weed control (CPWC) in potato. A four parameter log-logistic model was used to assist in monitoring and analysing two sets of related, relative crop yield. Data was obtained during the periods of increased weed interference and as a comparison, during weed-free periods. In both years, the relative yield of potato decreased with a longer period of weed-interference whereas increased with increasing length of weed free period. In 2012, the CPWC ranged from 112 to 1014 GDD (Growing Degree Days) which corresponded to 8 to 66 days after crop emergence (DAE) and between 135-958 GDD (10 to 63 DAE) in the following year based on a 5% acceptable yield loss. Weed-free conditions needed to be established as early as the first week after crop emergence and maintained as late as ten weeks after crop emergence to avoid more than 5% yield loss in the potato. The results suggest that CPWC could well assist potato producers to significantly reduce the expense of their weed management programs as well as improving its efficacy.

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Herbicide Timing and Rate Effects on Weed Management in Three Herbicide-Resistant Canola Systems

Weed Technology ◽

10.1614/wt-03-188r1 ◽

2004 ◽

Vol 18 (4) ◽

pp. 1006-1012 ◽

Cited By ~ 7

Author(s):

K. Neil Harker ◽

George W. Clayton ◽

John T. O'Donovan ◽

Robert E. Blackshaw ◽

F. Craig Stevenson

Keyword(s):

Weed Control ◽

Weed Management ◽

Management Practices ◽

Integrated Weed Management ◽

Weed Biomass ◽

Herbicide Resistant ◽

Leaf Stage ◽

Rate Effects ◽

Herbicide Timing ◽

Weed Removal

Herbicide-resistant canola dominates the canola market in Canada. A multiyear field experiment was conducted at three locations to investigate the effect of time of weed removal (two-, four-, or six-leaf canola) and herbicide rate (50 or 100% recommended) in three herbicide-resistant canola systems. Weeds were controlled in glufosinate-resistant canola (GLU) with glufosinate, in glyphosate-resistant canola (GLY) with glyphosate, and in imidazolinone-resistant canola (IMI) with a 50:50 mixture of imazamox and imazethapyr. Canola yields were similar among the three canola cultivar–herbicide systems. Yields were not influenced by 50 vs. 100% herbicide rates. Timing of weed removal had the greatest effect on canola yield, with weed removal at the four-leaf stage giving the highest yields in most cases. Percent dockage was often greater for GLU and IMI than for GLY. In comparison with the other treatments, dockage levels doubled for GLU after application at 50% herbicide rates. The consistency of monocot weed control was usually greater for GLY than for GLU or IMI systems. However, weed biomass data revealed no differences in dicot weed control consistency between IMI and GLY systems. Greater dockage and weed biomass variability after weed removal at the six-leaf stage or after low herbicide rates suggests higher weed seed production, which could constrain the adoption of integrated weed management practices in subsequent years.

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Weed-Control Systems for Peanut Grown as a Biofuel Feedstock

Weed Technology ◽

10.1614/wt-07-179.1 ◽

2008 ◽

Vol 22 (4) ◽

pp. 584-590 ◽

Cited By ~ 3

Author(s):

Wilson H. Faircloth ◽

Jason A. Ferrell ◽

Christopher L. Main

Keyword(s):

Control Systems ◽

Weed Control ◽

Low Cost ◽

Field Studies ◽

Peanut Oil ◽

Oil Yield ◽

Oilseed Crop ◽

Application Timing ◽

The Cost ◽

On Farm

Peanuts are not often used as a true oilseed crop, especially for the production of fuel. However, peanut could be a feedstock for biodiesel, especially in on-farm or small cooperative businesses, where producers can dictate the cost of making their own fuel. Field studies were conducted in 2005 and 2006 to assess low-cost weed-control systems for peanuts that would facilitate the economic viability of peanut biodiesel. Four preselected herbicide costs ranging from $25 to $62/ha and two application timings were compared with nontreated ($0/ha) and typical ($115/ha) herbicide programs for weed control and peanut oil yield. A peanut oil yield goal of 930 L/ha was exceeded with multiple low-cost herbicide systems in 3 of 4 site–yr. The main effect of application timing was only significant for a single site–year in which oil yield increased linearly with cost of the PRE and POST weed-control system. An herbicide cost of $50/ha, using PRE and POST applications, was consistently among the highest in oil yield, regardless of site–year, exceeding the typical (high value) programs in 3 of 4 site–yr. Use of reduced rates of imazapic (0.5× or 0.035 kg ai/ha) was detrimental in 2 of 4 site–yr. Weed control, and thus oil yields, were most dependent on species present at each location and not on input price. Data from this series of studies will allow researchers and entrepreneurs to more accurately assess the viability and sustainability of peanut biodiesel.

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Competitiveness of Herbicide-Resistant Waterhemp (Amaranthus tuberculatus) with Soybean

Weed Science ◽

10.1017/wsc.2018.45 ◽

2018 ◽

Vol 66 (6) ◽

pp. 729-737 ◽

Cited By ~ 2

Author(s):

Thomas R. Butts ◽

Bruno C. Vieira ◽

Débora O. Latorre ◽

Rodrigo Werle ◽

Greg R. Kruger

Keyword(s):

Weed Management ◽

Management Practices ◽

Cropping Systems ◽

Biomass Accumulation ◽

Stem Diameter ◽

The Other ◽

Harvest Time ◽

Herbicide Resistant ◽

Amaranthus Tuberculatus ◽

Soybean Plants

AbstractWaterhemp [Amaranthus tuberculatus(Moq.) J. D. Sauer] is a troublesome weed occurring in cropping systems throughout the U.S. Midwest with an ability to rapidly evolve herbicide resistance that could be associated with competitive disadvantages. Little research has investigated the competitiveness of differentA. tuberculatuspopulations under similar environmental conditions. The objectives of this study were to evaluate: (1) the interspecific competitiveness of three herbicide-resistantA. tuberculatuspopulations (2,4-D and atrazine resistant [2A-R], glyphosate and protoporphyrinogen oxidase [PPO]-inhibitor resistant [GP-R], and 2,4-D, atrazine, glyphosate, and PPO-inhibitor susceptible [2AGP-S]) with soybean [Glycine max(L.) Merr.]; and (2) the density-dependent response of eachA. tuberculatuspopulation within a constant soybean population in a greenhouse environment.Amaranthus tuberculatuscompetitiveness with soybean was evaluated across five target weed densities of 0, 2, 4, 8, and 16 plants pot−1(equivalent to 0, 20, 40, 80, and 160 plants m−2) with 3 soybean plants pot−1(equivalent to 300,000 plants ha−1). At the R1 soybean harvest time, no difference in soybean biomass was observed acrossA. tuberculatuspopulations. AtA. tuberculatusdensities <8 plants pot−1, the 2AGP-S population had the greatest biomass and stem diameter per plant. At the R7 harvest time, the 2AGP-S population caused the greatest loss in soybean biomass and number of pods compared with the other populations at densities of <16 plants pot−1. The 2AGP-S population had greater early-season biomass accumulation and stem diameter compared with the otherA. tuberculatuspopulations, which resulted in greater late-season reduction in soybean biomass and number of pods. This research indicates there may be evidence of interspecific competitive fitness cost associated with the evolution of 2,4-D, atrazine, glyphosate, and PPO-inhibitor resistance inA. tuberculatus. Focus should be placed on effectively using cultural weed management practices to enhance crop competitiveness, especially early in the season, to increase suppression of herbicide-resistantA. tuberculatus.

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The influence of soybean population and POST herbicide application timing on in-season and subsequent-season Palmer amaranth (Amaranthus palmeri) control and economic returns

Weed Technology ◽

10.1017/wet.2020.87 ◽

2020 ◽

pp. 1-7

Author(s):

Denis J. Mahoney ◽

David L. Jordan ◽

Andrew T. Hare ◽

Nilda Roma-Burgos ◽

Katherine M. Jennings ◽

...

Keyword(s):

Weed Control ◽

High Density ◽

Palmer Amaranth ◽

Economic Returns ◽

Herbicide Application ◽

Application Timing ◽

Herbicide Resistant ◽

Resistance Evolution ◽

Subsequent Crop ◽

Density Population

Abstract Overreliance on herbicides for weed control has led to the evolution of herbicide-resistant Palmer amaranth populations. Farm managers should consider the long-term consequences of their short-term management decisions, especially when considering the soil weed seedbank. The objectives of this research were to (1) determine how soybean population and POST herbicide application timing affects in-season Palmer amaranth control and soybean yield, and (2) how those variables influence Palmer amaranth densities and cotton yields the following season. Soybeans were planted (19-cm row spacing) at a low-, medium-, and high-density population (268,000, 546,000, and 778,000 plants ha–1, respectively). Fomesafen and clethodim (280 and 210 g ai ha–1, respectively) were applied at the VE, V1, or V2 to V3 soybean growth stage. Nontreated plots were also included to assess the effect of soybean population alone. The following season, cotton was planted into these plots so as to understand the effects of soybean planting population on Palmer amaranth densities in the subsequent crop. When an herbicide application occurred at the V1 or V2 to V3 soybean stage, weed control in the high-density soybean population increased 17% to 23% compared to the low-density population. Economic return was not influenced by soybean population and was increased 72% to 94% with herbicide application compared to no treatment. In the subsequent cotton crop, Palmer amaranth densities were 24% to 39% lower 3 wk after planting when following soybean sprayed with herbicides compared to soybean without herbicides. Additionally, Palmer amaranth densities in cotton were 19% lower when soybean was treated at the VE stage compared to later stages. Thus, increasing soybean population can improve Palmer amaranth control without adversely affecting economic returns and can reduce future weed densities. Reducing the weed seedbank and selection pressure from herbicides are critical in mitigating resistance evolution.

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