Comparison of Herbicide Tactics to Minimize Species Shifts and Selection Pressure in Glyphosate-Resistant Soybean

There are significant concerns over the long- and short-term implications of continuous glyphosate use and potential problems associated with weed species shifts and the development of glyphosate-resistant weed species. Field research was conducted to determine the effect of herbicide treatment and application timing on weed control in glyphosate-resistant soybean. Ten herbicide treatments were evaluated that represented a range of PPI, PRE, and POST-only application timings. All herbicide treatments included a reduced rate of glyphosate applied POST. PRE herbicides with residual properties followed by (fb) glyphosate POST provides more effective control of broadleaf weed species than POST-only treatments. There was no difference in soybean yield between PRE fb POST and POST-only treatments in 2008. Conversely, PRE fb POST herbicide treatments resulted in greater yield than POST-only treatments in 2009. Using PRE fb POST herbicide tactics improves weed control and reduces the risk for crop yield loss when dealing with both early- and late-emerging annual broadleaf weed species across variable cropping environments.

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Effectiveness of Metribuzin Applied Preemergence for Economical Control of Common Cocklebur in Soybeans

Weed Science ◽

10.1017/s0043174500066236 ◽

1976 ◽

Vol 24 (4) ◽

pp. 385-390 ◽

Cited By ~ 16

Author(s):

C. G. McWhorter ◽

J. M. Anderson

Keyword(s):

Glycine Max ◽

Moisture Content ◽

Control Systems ◽

Weed Control ◽

Soybean Seed ◽

Field Research ◽

Effective Control ◽

Foreign Material ◽

Herbicide Treatments ◽

Sequential Treatments

The effectiveness of several preemergence and postemergence weed control systems for control of common cocklebur (Xanthium pensylvanicumWallr.) in soybeans [Glycine max(L.) Merr.] was determined in field research over a 3-yr period. Sequential applications of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)one] at 1.1 kg/ha applied preemergence, and dinoseb (2-sec-butyl-4,6-dinitrophenol) at 1.7 kg/ha, 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid] at 0.2 kg/ha, or bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide] at 1.1 kg/ha applied postemergence, provided at least 90% control of common cocklebur and increased soybean yields. Use of single herbicide applications was less effective than sequential applications, but metribuzin applied preemergence was more effective in controlling common cocklebur and increasing soybean yields than single applications of any herbicide applied postemergence. Effective control of common cocklebur with sequential herbicide treatments increased soybean seed grades by reducing discounts caused by several grade lowering components including moisture content and foreign material in harvested seed. Use of all herbicide practices increased returns above specified costs, but greatest returns followed use of sequential treatments.

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Effect of Residual Herbicide and Postemergence Application Timing on Weed Control and Yield in Glyphosate-Resistant Corn

Weed Technology ◽

10.1614/wt-d-10-00052.1 ◽

2011 ◽

Vol 25 (1) ◽

pp. 19-24 ◽

Cited By ~ 12

Author(s):

Mark M. Loux ◽

Anthony F. Dobbels ◽

William G. Johnson ◽

Bryan G. Young

Keyword(s):

Weed Control ◽

Effective Control ◽

Weed Species ◽

Timing Control ◽

Application Timing ◽

Common Lambsquarters ◽

Late Season ◽

Redroot Pigweed ◽

Giant Foxtail ◽

Giant Ragweed

Field studies were conducted in 2007 and 2008 at seven sites in Ohio, Indiana, and Illinois to determine the effect of PRE herbicide and POST application timing on weed control and yield of glyphosate-resistant corn. Levels of PRE herbicide included none; low—atrazine; medium—atrazine and metolachlor; and high—atrazine, mesotrione, and metolachlor. Glyphosate was applied POST when corn was 30 cm tall, or 1 or 2 wk later. Common lambsquarters, giant foxtail, and giant ragweed infested at least six of the seven sites, and other weed species occurred at two to three sites. Control of weeds at the time of POST application ranged from 48 to 91%, 58 to 99%, and 87 to 100% for the low, medium, and high levels of PRE herbicide, respectively, averaged over POST application timing. Control of giant foxtail and redroot pigweed decreased by about 20% between the second and third POST timing, averaged over PRE herbicide, but control of other weeds was similar among timings. Late-season control of common ragweed, velvetleaf, common lambsquarters, and Pennsylvania smartweed exceeded 90%, regardless of PRE herbicide or POST timing. Control of redroot pigweed, ivyleaf morningglory, and giant ragweed was as low as 74, 67, and 83%, respectively, but the high level of PRE herbicide resulted in 90 to 97% control of these weeds. An interaction between PRE herbicide and POST timing for late-season control of giant foxtail, tall waterhemp, and yellow nutsedge reflected the more effective control among POST timings from the higher levels of PRE herbicide. The overall trend in this study was for more effective weed control in PRE/POST herbicide programs with more comprehensive PRE herbicides that have substantial activity on both grass and broadleaf weeds. Highest yield occurred where the PRE treatment consisted of a two- or three-way combination of herbicides applied at 50% of the recommended rate or higher. Yield was reduced at all POST timings with atrazine alone or in the absence of PRE herbicide.

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Seed Production and Control of Sicklepod (Senna obtusifolia) and Pitted Morningglory (Ipomoea lacunosa) with 2,4-D, Dicamba, and Glyphosate Combinations

Weed Technology ◽

10.1614/wt-d-15-00108.1 ◽

2016 ◽

Vol 30 (1) ◽

pp. 76-84 ◽

Cited By ~ 5

Author(s):

Ramon G. Leon ◽

Jason A. Ferrell ◽

Brent A. Sellers

Keyword(s):

Seed Production ◽

Crop Production ◽

Field Experiments ◽

Effective Control ◽

Weed Species ◽

Application Timing ◽

Pitted Morningglory ◽

Herbicide Treatments ◽

Viable Seeds ◽

And Control

Sicklepod and pitted morningglory are two of the most important weed species in row-crop production in the southeastern United States. The upcoming introduction of soybean and cotton varieties resistant to 2,4-D and dicamba will increase the reliance on these auxinic herbicides. However, it is not clear how these herbicides will affect sicklepod and pitted morningglory control. Field experiments were conducted in 2013 and 2014 in Jay, FL to determine whether 2,4-D (560 and 1,120 g ae ha−1), dicamba (420 and 840 g ae ha−1), and glyphosate (1,060 g ae ha−1) alone or in combination applied when weed shoots were 11 (early POST [EPOST]) and 22 (late POST [LPOST]) cm long effectively control and prevent seed production of sicklepod and pitted morningglory. LPOST provided more effective control of sicklepod than EPOST. This was attributed to emergence of sicklepod seedlings after the EPOST application. When glyphosate was tank mixed with 2,4-D or dicamba, sicklepod control was higher (78 to 89% and 87 to 98% in 2013 and 2014, respectively) than for single-herbicide treatments (45 to 77% and 38 to 80% in 2013 and 2014, respectively) 6 wk after treatment (WAT). Pitted morningglory control was not affected by application timing, and 2,4-D provided 91 to 100% 6 WAT, which was equivalent to treatments with tank mixtures containing glyphosate. Dicamba applied at 420 g ha−1had the lowest pitted morningglory control (44 to 70% and 82 to 86% in 2013 and 2014, respectively). Sicklepod and pitted morningglory plants that survived and recovered from herbicide treatments produced the same number of viable seeds as nontreated plants in most treatments. The results of the present study indicated that the use of 2,4-D and dicamba alone will not provide adequate extended control of sicklepod, and the use of tank mixtures that combine auxinic herbicides with glyphosate or other POST herbicides will be necessary to manage sicklepod adequately in 2,4-D- or dicamba-resistant soybean and cotton. Because sicklepod plants that survived a single herbicide application are capable of producing abundant viable seeds, integrated approaches that include PRE herbicides and sequential POST control options may be necessary to ensure weed seed bank reductions.

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(220) Pelargonic Acid Weed Control Parameters

HortScience ◽

10.21273/hortsci.41.4.1034d ◽

2006 ◽

Vol 41 (4) ◽

pp. 1034D-1034 ◽

Cited By ~ 1

Author(s):

Charles L. Webber ◽

James W. Shrefler

Keyword(s):

Weed Control ◽

Field Research ◽

Pelargonic Acid ◽

Nonanoic Acid ◽

Ionic Surfactant ◽

Application Timing ◽

Weed Growth ◽

Time Period ◽

Visual Damage ◽

Multiple Species

Producers and researchers are interested in pelargonic acid (nonanoic acid) as a broad-spectrum postemergence or burn-down herbicide. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods we consume. The objective of this research was to determine the effect of pelargonic acid concentration, adjuvants, and application timing on weed control efficacy as a burn-down herbicide. Field research was conducted at Lane, Okla. (southeast Oklahoma), during the 2005 growing season. One month prior to spraying the weed control treatments, the land was cultivated to kill the existing weeds and provide a uniform seed bed for new weed growth. The factorial weed control treatments included three application concentrations of Scythe (57.0% pelargonic acid) applied at 3%, 6.5%, and 10%; three adjuvants (none, orange oil, and non-ionic surfactant); and two application dates. All herbicide treatments were applied with an application volume of 935 L/ha to seedling weeds. The experiment had a high weed density with multiple species of grass and broadleaf weeds. Weed control across species increased as the herbicide concentrations increased from 0% to 10%. At all concentrations applied, pelargonic acid produced greater weed control for a longer time period for the broadleaf weeds than the grass weeds. Visual damage to the weeds was often apparent within a few hours after application. There was a significant increase in weed control when applied to the younger weeds. In this research, pelargonic acid was effective in controlling both broadleaf and grass weeds as a burn-down herbicide, although crabgrass was tougher to control.

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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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Weed Control Using an Enclosed Thermal Heating Apparatus

Weed Technology ◽

10.1614/wt-d-12-00057.1 ◽

2012 ◽

Vol 26 (4) ◽

pp. 699-707 ◽

Cited By ~ 6

Author(s):

Jared A. Hoyle ◽

J. Scott McElroy ◽

J. Jack Rose

Keyword(s):

Weed Control ◽

Field Research ◽

Control Treatment ◽

Thermal Treatments ◽

Application Timing ◽

Yellow Nutsedge ◽

Virginia Buttonweed ◽

Turfgrass Establishment ◽

Fall Application ◽

Large Crabgrass

Weed control by heat or flaming typically uses flames to burn small weeds, directed away from desired crops. This research studied an enclosed flaming system for weed control before turfgrass establishment. Field research trials were conducted to explore the efficacy of a PL-8750 flame sanitizer at two application timings. Treatments included various application methods of PL-8750 flame sanitizer and common thermal and chemical weed control methods. Data were weed control relative to the control treatment. Species evaluated included carpetweed, Virginia buttonweed, spotted spurge, large crabgrass, goosegrass, old world diamond-flower, cocks-comb kyllinga, and yellow nutsedge. Turfgrass establishment was not successful in summer but was successful in fall. Fall-application timing trials resulted in > 60% tall fescue establishment at 6 wk after seeding (WAS) for all treatments. Summer-application timing trials resulted in unacceptable turfgrass establishment (≤ 18%) for all evaluated turfgrass species at 6 WAS. Broadleaf and grassy weeds were better controlled compared with sedge weeds. Overall, solarization; covered, emerged-weed flaming; and double applications of covered, emerged-weed flaming were the most successful treatments. Solarization controlled carpetweed, Virginia buttonweed, spotted spurge, large crabgrass, and goosegrass > 80% at 6 WAS. Weed control across thermal treatments were equal to or greater than the comparison chemical treatment (dazomet at 389 kg ha−1). Results indicate thermal weed control has potential for reducing weed populations before turfgrass establishment.

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Weed control in lucerne in New Zealand

Outlook on Agriculture ◽

10.1177/003072707400800106 ◽

1974 ◽

Vol 8 (1) ◽

pp. 29-33

Author(s):

W F Leonard

Keyword(s):

New Zealand ◽

Weed Control ◽

Effective Control ◽

Weed Species ◽

Wide Range ◽

Yield Quality ◽

Useful Life

Weeds affect the establishment, yield, quality and useful life of lucerne. The herbicide 2,4-DB controls weeds selectively in the newly-sown crop, or benfluralin can be used pre-emergence. In the established crop, paraquat, sprayed annually before spring growth commences–-either alone or in mixture with a triazine–-provides effective control of a wide range of weed species.

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Influence of Weed Control Programs in Intensive Cropping Systems

Weed Science ◽

10.1017/s0043174500059956 ◽

1984 ◽

Vol 32 (6) ◽

pp. 762-767 ◽

Cited By ~ 6

Author(s):

N. C. Glaze ◽

C. C. Dowler ◽

A. W. Johnson ◽

D. R. Sumner

Keyword(s):

Weed Control ◽

Cropping Systems ◽

Weed Species ◽

Multiple Cropping ◽

Control Programs ◽

Yellow Nutsedge ◽

Herbicide Treatments ◽

Intensive Cropping ◽

Main Effects ◽

Herbicide Programs

Six multiple-cropping systems composed of: a) turnip (Brassica campestrisspp.rapifera), corn (Zea maysL.), and snapbean (Phaseolus vulgarisL.); b) turnip, peanut (Arachis hypogaeaL.), and snapbean; c) turnip, corn, and turnip; d) turnip, peanut, and turnip; e) snapbean, soybean [Glycine max(L.) Merr.], and cabbage (Brassica oleraceaL.); and f) turnip, cucumber (Cucumis sativusL.), cowpea [Vigna unguiculata(L.) Walp.], and turnip were subjected to nematicide and weed control programs of cultivation or herbicides. Herbicide programs were superior to cultivation in control of weeds. Weeds remaining in the row following cultivation competed severely with crops. Weed species remaining were altered depending on the method of control and crop. Yellow nutsedge (Cyperus esculentusL. ♯3CYPES) increased rapidly in all herbicide programs but not in cultivated plots. Pigweeds (Amaranthusspp.) were controlled by herbicides but increased in cultivated plots. Corn, peanut, soybean, and spring snapbean yields were higher in herbicide treatments than in cultivated treatments. Cucumber was the only crop that had increased yields for both main effects, herbicide and nematicide. Turnip was consistently injured in herbicide treatments, which was believed to be caused by residues from previous crops interacting with pathogens and possible allelopathic effects of decaying organic matter.

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Environmental Impact of Glyphosate-Resistant Weeds in Canada

Weed Science ◽

10.1614/ws-d-13-00093.1 ◽

2014 ◽

Vol 62 (2) ◽

pp. 385-392 ◽

Cited By ~ 18

Author(s):

Hugh J. Beckie ◽

Peter H. Sikkema ◽

Nader Soltani ◽

Robert E. Blackshaw ◽

Eric N. Johnson

Keyword(s):

Environmental Impact ◽

Weed Control ◽

Acetolactate Synthase ◽

Application Rate ◽

Weed Species ◽

Common Ragweed ◽

Herbicide Resistant ◽

Herbicide Treatments ◽

Relative Potential ◽

Synthase Inhibitor

Glyphosate-resistant (GR) giant ragweed, horseweed, and common ragweed were confirmed in southwestern Ontario, Canada in 2008, 2010, and 2011, respectively. In the western prairie provinces of Alberta and Saskatchewan, GR (plus acetolactate synthase inhibitor-resistant) kochia was discovered in 2011. This symposium paper estimates the environmental impact (EI) of the top herbicide treatments or programs used to manage these GR weed species in the major field crops grown in each region. For each herbicide treatment, EI (per ha basis) was calculated as the environmental impact quotient (EIQ), which quantifies the relative potential risk of pesticide active ingredients on human and ecological health based on risk components to farm workers, consumers, and the environment, multiplied by the application rate (kg ai ha−1). Total EI is defined as EI (per ha basis) multiplied by the application area (i.e., land area affected by a GR weed). It was assumed that all herbicide treatments would supplement the continued usage of glyphosate because of its broad spectrum weed control. For the control of these GR weeds, most treatments contain auxinic or protoporphyrinogen oxidase (PPO)-inhibiting herbicides. The majority of auxinic herbicide treatments result in low (EI ≤ 10) to moderate (11 to 20) EI, whereas all treatments of PPO inhibitors have low EI. Total EI of GR horseweed and kochia will generally be greater than that of giant or common ragweed because of rapid seed dispersal. For recommended herbicide treatments to control GR weeds (and herbicide-resistant weeds in general), EI data should be routinely included with cost and site of action in weed control extension publications and software, so that growers have the information needed to assess the EI of their actions.

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Interaction of Rice Residue and PRE Herbicides on Emergence and Biomass of Four Weed Species

Weed Technology ◽

10.1614/wt-d-12-00067.1 ◽

2012 ◽

Vol 26 (4) ◽

pp. 627-632 ◽

Cited By ~ 11

Author(s):

Bhagirath S. Chauhan ◽

Seth B. Abugho

Keyword(s):

Weed Control ◽

Seedling Emergence ◽

Conservation Agriculture ◽

Bare Soil ◽

Weed Species ◽

Herbicide Treatments ◽

Agriculture Systems

Studies were conducted in a screenhouse to determine the interaction of rice residue as mulch (0, 3, and 6 t ha−1) and herbicides (nontreated, oxadiazon at 0.5 and 1.0 kg ai ha−1, and pendimethalin at 1.0 and 2.0 kg ai ha−1) on seedling emergence and biomass of barnyardgrass, crowfootgrass, junglerice, and rice flatsedge. Regardless of the residue amount, crowfootgrass and junglerice were effectively controlled by all herbicide treatments. No seedlings of these weed species escaped the herbicides when applied in the presence of residue cover. There was no survival of barnyardgrass seedlings when both herbicides were applied on bare soil (without residue cover); however, some seedlings survived oxadiazon and pendimethalin when applied in the presence of residue cover. For rice flatsedge, the herbicide applications in the presence of residue cover resulted in lower weed control than in the absence of residue. These results suggest that some weed species can escape the application of PRE herbicides in conservation agriculture systems in which residue can bind soil-applied herbicides and result in lower efficacy.

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