Dicamba-Tolerant Soybean Combined Cover Crop to Control Palmer amaranth

Montgomery, Garret B.; McClure, Angela; Hayes, Robert M.; Walker, Forbes; Senseman, Scott A.; Steckel, Lawrence E.

doi:10.1017/wet.2017.96

Cited by 23 publications

(20 citation statements)

References 44 publications

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“…Resistance will evolve independently in fields that continue to have intensive selection pressure from PPO inhibitors. Many are advocating alternative and integrated management methods 61–63 that include as many nonchemical approaches as possible 64,65 …”

Section: Resultsmentioning

confidence: 99%

Functional PPO2 mutations: co‐occurrence in one plant or the same ppo2 allele of herbicide‐resistant Amaranthus palmeri in the US mid‐south

Noguera

Rangani

Heiser

et al. 2020

Pest Management Science

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BACKGROUND Protoporphyrinogen IX oxidase 2 (PPO2) inhibitors are important for the management of glyphosate‐ and acetolactate synthase‐resistant Palmer amaranth [Amaranthus palmeri (S.) Wats.]. The evolving resistance to PPO inhibitors is of great concern. We surveyed the evolution of resistance to fomesafen in the US Mid‐south and determined its correlation with the known functional PPO2 target‐site mutations (TSM). RESULTS The 167 accessions analyzed were grouped into five categories, four resistant (147) and one susceptible (20). Arkansas accessions constituted 100% of the susceptible group while the Missouri accessions comprised 60% of the most resistant category. The majority of Mississippi accessions (88%) clustered in the high‐survival‐high‐injury category, manifesting an early‐stage resistance evolution. One hundred and fifteen accessions were genotyped for four known TSMs; 74% of accessions carried at least one TSM. The most common single TSM was ΔG210 (18% of accessions) and the predominant double mutation was ΔG210 + G399A (17%). Other mutations are likely less favorable, hence are rare. All TSMs were detected in three accessions. Further examination revealed that 9 and two individuals carried G399A + G210 and G399A + R128G TSM in the same allele, respectively. The existence of these combinations is supported by molecular modeling. CONCLUSIONS Resistance to PPO inhibitors is widespread across the Mid‐southern USA. Highly resistant field populations have plants with multiple mutations. G399A is the most prone to co‐occur with other ppo2 mutations in the same allele. Mutation at R128 in the configuration of the PPO2 catalytic domain restrains the co‐occurrence of R128G with ΔG210, making ΔG210 + G399A the most plausible, tolerable functional mutation combination to co‐occur in the same ppo2 allele.

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Section: Resultsmentioning

confidence: 99%

Functional PPO2 mutations: co‐occurrence in one plant or the same ppo2 allele of herbicide‐resistant Amaranthus palmeri in the US mid‐south

Noguera

Rangani

Heiser

et al. 2020

Pest Management Science

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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%

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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“…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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Dicamba-Tolerant Soybean Combined Cover Crop to Control Palmer amaranth

Cited by 23 publications

References 44 publications

Functional PPO2 mutations: co‐occurrence in one plant or the same ppo2 allele of herbicide‐resistant Amaranthus palmeri in the US mid‐south

Functional PPO2 mutations: co‐occurrence in one plant or the same ppo2 allele of herbicide‐resistant Amaranthus palmeri in the US mid‐south

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

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