Influence of Cover Crops on Management of <i>Amaranthus</i> Species in Glyphosate- and Glufosinate-Resistant Soybean

Loux, Mark M.; Dobbels, Anthony F.; Bradley, Kevin W.; Johnson, William G.; Young, Bryan G.; Spaunhorst, Douglas J.; Norsworthy, Jason K.; Palhano, Matheus; Steckel, Lawrence E.

doi:10.1017/wet.2017.30

Cited by 19 publications

(22 citation statements)

References 30 publications

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“…Our results do not provide supporting evidence that surface residue mulch reduced herbicide efficacy or cash crop yields. Recent studies in corn and soybean production regions of the Midwest and Midsouth support the inference that herbicide inputs are the primary driver of cash crop yields and weed control performance, including multiple herbicide-resistant Amaranthus spp., when cover crops are integrated as a component of an IWM strategy (Loux et al 2017;Montgomery et al 2018;Wiggins et al 2015).…”

Section: Weed Control and Yield Performance Targetsmentioning

confidence: 99%

“…Recent studies have demonstrated that integrating cover crops can increase suppression of glyphosateresistant weeds, including fall-and spring-emerging horseweed [Conyza canadensis (L.) Cronquist] (Cholette et al 2018;Pittman et al 2019;Wallace et al 2019) and summer annuals Palmer amaranth (Amaranthus palmeri S. Watson) and waterhemp [Amaranthus tuberculatus (Moq.) Sauer] (Loux et al 2017;Montgomery et al 2018;Wiggins et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…The contribution of cover crops to zero seed rain management of multiple herbicide-resistant weeds remains equivocal. For example, previous studies have concluded that multiple-pass and multiple site-of-action weed control programs are still needed, regardless of cover crop selection and management, to control multiple herbicide-resistant species such as A. palmeri (Loux et al 2017). Consequently, when viewed as a prescriptive tool for achieving a zero seed rain management goal, integrating cover crops may be perceived by growers as contributing to additional weed control input costs, agronomic management complexity, or reduced yields due to incomplete termination of cover crops or unanticipated trade-offs related to soil fertility, crop establishment, and pest dynamics.…”

Section: Introductionmentioning

confidence: 99%

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Alternative performance targets for integrating cover crops as a proactive herbicide-resistance management tool

et al. 2020

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Intensified cover cropping practices are increasingly viewed as an herbicide resistance management tool but clear distinction between reactive and proactive resistance management performance targets is needed. We evaluated two proactive performance targets for integrating cover cropping tactics, including (1) facilitation of reduced herbicide inputs, and (2) reduced herbicide selection pressure. We conducted corn (Zea mays L.) and soybean [Glycine max (L.) Merr] field experiments in Pennsylvania and Delaware using synthetic weed seedbanks of horseweed [Conyza canadensis (L.) Cronquist] and smooth pigweed (Amaranthus hybridus L.) to assess winter- and summer- annual population dynamics, respectively. The effect of alternative cover crops was evaluated across a range of herbicide inputs. Cover crop biomass production ranged from 2,000 to 8,500 kg ha-1 in corn and 3,000 to 5,500 kg ha-1 in soybean. Experimental results demonstrated that herbicide-based tactics were the primary drivers of total weed biomass production with cover cropping tactics providing an additive weed suppression benefit. Substitution of cover crops for PRE or POST herbicide programs did not reduce total weed control levels or cash crop yields but did result in lower net returns due to higher input costs. Cover cropping tactics significantly reduced C. canadensis populations in three of four cover crop treatments and decreased the number of large rosettes (> 7.6 cm diameter) at the time of pre-plant herbicide exposure. Substitution of cover crops for PRE herbicides resulted in increased selection pressure on POST herbicides, but reduced the number of large individuals (> 10 cm) at POST applications. Collectively, our findings suggest that cover crops can reduce the intensity of selection pressure on POST herbicides but the magnitude of the effect varies based on weed life-history traits. Additional work is needed to describe proactive resistance management concepts and performance targets for integrating cover crops so producers can apply these concepts in site-specific, within-field management practices.

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Section: Weed Control and Yield Performance Targetsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Alternative performance targets for integrating cover crops as a proactive herbicide-resistance management tool

et al. 2020

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“…First, recent studies have consistently demonstrated that integrating cover crops into annual grain crop rotations can improve suppression of current glyphosate-resistant weeds, including horseweed (Erigeron canadensis L.; Cholette et al 2018) and Amaranthus spp. (Loux et al 2017;Montgomery et al 2018;Wiggins et al 2016). And second, cover crops are increasingly integrated into annual grain crop rotations to provide multiple ecosystem services, including improved soil quality, maintenance of nutrient and water cycling, and enhanced biotic pest regulation (Wayman et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Cover crop effects on horseweed (Erigeron canadensis) density and size inequality at the time of herbicide exposure

2019

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Proactive integrated weed management (IWM) is critically needed in no-till production to reduce the intensity of selection pressure for herbicide-resistant weeds. Reducing the density of emerged weed populations and the number of larger individuals within the population at the time of herbicide application are two practical management objectives when integrating cover crops as a complementary tactic in herbicide-based production systems. We examined the following demographic questions related to the effects of alternative cover-cropping tactics following small grain harvest on preplant, burndown management of horseweed (Erigeron canadensis L.) in no-till commodity-grain production: (1) Do cover crops differentially affect E. canadensis density and size inequality at the time of herbicide exposure? (2) Which cover crop response traits are drivers of E. canadensis suppression at time of herbicide exposure? Interannual variation in growing conditions (study year) and intra-annual variation in soil fertility (low vs. high nitrogen) were the primary drivers of cover crop response traits and significantly affected E. canadensis density at the time of herbicide exposure. In comparison to the fallow control, cover crop treatments reduced E. canadensis density 52% to 86% at the time of a preplant, burndown application. Cereal rye (Secale cereale L.) alone or in combination with forage radish (Raphanus sativus L.) provided the most consistent E. canadensis suppression. Fall and spring cover crop biomass production was negatively correlated with E. canadensis density at the preplant burndown application timing. Our results also show that winter-hardy cover crops reduce the size inequality of E. canadensis populations at the time of herbicide exposure by reducing the number of large individuals within the population. Finally, we advocate for advancement in our understanding of complementarity between cover crop– and herbicide-based management tactics in no-till systems to facilitate development of proactive, herbicide-resistant management strategies.

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“…These programs would increase selection for resistance to postemergence herbicides and result in the possible failure of a postemergence program because of large weed sizes and high weed densities when environmental conditions are not conducive to a timely application. Residual herbicides are also recommended to be included in early postemergence applications to suppress emerging Palmer amaranth until canopy formation is achieved (Loux et al., 2017). Glufosinate, 2,4‐D, and dicamba all have excellent activity on PPO‐resistant Palmer amaranth; these programs were shown here to provide an extended period of weed control.…”

Section: Resultsmentioning

confidence: 99%

Comparison of weed control technologies for protoporphyrinogen oxidase‐resistant Palmer amaranth

Houston

Barber

Norsworthy

et al. 2020

Crop Forage & Turfgrass Mgmt

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Confirmation of protoporphyrinogen oxidase (PPO)‐resistant Palmer amaranth (Amaranthus palmeri S.Watson) in 2015 limited weed control options for soybean [Glycine max (L.) Merr.] producers. With already prevalent 5‐enolpyruvyl‐shikimate‐3‐phosphate synthase‐, acetolactate synthase‐, beta‐tubulin‐, and very‐long‐chain fatty acid‐resistant Palmer amaranth, there are few remaining effective pre‐emergence and postemergence herbicides labeled in soybean. The recent commercialization of soybean varieties resistant to dicamba and 2,4‐D give producers effective options to control multiresistant Palmer amaranth. To evaluate new and existing technologies and postemergence herbicide options, two experiments were conducted in 2017. These experiments were conducted in Marion and Crawfordsville, AR, two locations with confirmed PPO‐, 5‐enolpyruvyl‐shikimate‐3‐phosphate synthase‐, acetolactate synthase‐, beta‐tubulin‐, and very‐long‐chain fatty acid‐resistant Palmer amaranth. Each technology was tested over three pre‐emergence programs with distinct levels of control (74, 88, and 95%). At 28 d after pre‐emergence, the first postemergence applications were made when Palmer amaranth was approximately 4 in in height. Fourteen days later, visible weed control ratings showed that glufosinate‐, 2,4‐D‐, and dicamba‐resistant programs resulted in at least 95% control of Palmer amaranth across all pre‐emergence treatments, better than the 83% control provided by the glyphosate‐resistant soybean program. Visible control ratings taken 14 d after the second postemergence treatment showed separation between the glufosinate‐ (97%), 2,4‐D‐ (97%), and the dicamba‐resistant (96%) programs from the glyphosate‐resistant program (59%). The results indicate that effective pre‐emergence programs followed by postemergence programs containing glufosinate, 2,4‐D, or dicamba will provide extended control of PPO‐resistant Palmer amaranth but this may not be feasible in a glyphosate‐resistant soybean system.

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Influence of Cover Crops on Management of Amaranthus Species in Glyphosate- and Glufosinate-Resistant Soybean

Cited by 19 publications

References 30 publications

Alternative performance targets for integrating cover crops as a proactive herbicide-resistance management tool

Alternative performance targets for integrating cover crops as a proactive herbicide-resistance management tool

Cover crop effects on horseweed (Erigeron canadensis) density and size inequality at the time of herbicide exposure

Comparison of weed control technologies for protoporphyrinogen oxidase‐resistant Palmer amaranth

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