Winter annual grass control and crop safety in quizalofop‐resistant wheat cultivars

Hildebrandt, Curtis; Haley, Scott D.; Shelton, Chad W.; Westra, Eric P.; Westra, Phil; Gaines, Todd A.

doi:10.1002/agj2.20998

Cited by 5 publications

(10 citation statements)

References 51 publications

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“…eastern Colorado, which showed consistent downy brome control with QP regardless of the rates and adjuvants used (Hildebrandt et al 2022). Downy brome control was ≥95% at 60 DASP for all QP rates (31, 46, 62, 77, 93, and 109 g ai ha −1 ) and adjuvants (COC, MSO, NIS, UAN).…”

Section: Weed Technologymentioning

confidence: 80%

Feral rye (Secale cereale L.) control in quizalofop-resistant winter wheat in Oregon

Ribeiro,

Mallory-Smith,

Gourlie

et al. 2023

Weed Technol

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Managing winter annual grass weeds has long been a challenge in the dryland soft white winter wheat-producing regions of the Pacific Northwest (PNW). The recent development of quizalofop-resistant (CoAXium) wheat varieties allows growers to use the acetyl-CoA carboxylase (ACCase)-inhibiting herbicide quizalofop (QP) for postemergence grass control. Field experiments were conducted over two winter wheat growing seasons in 2021-2022 and 2022-2023 near Adams, OR, to evaluate QP efficacy on feral rye and for crop safety. Downy brome and jointed goatgrass control with QP were assessed in 2021-2022 and 2022-2023, respectively. Quizalofop treatments provided effective feral rye (≥ 95%), downy brome (≥ 87%), and jointed goatgrass (99%) control regardless of rates, adjuvants, and spray volumes tested. Spring-applied QP caused no winter wheat injury. Results indicate that the quizalofop-resistant wheat technology can help PNW wheat growers selectively control winter annual grasses.

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Section: Weed Technologymentioning

confidence: 80%

Feral rye (Secale cereale L.) control in quizalofop-resistant winter wheat in Oregon

Ribeiro,

Mallory-Smith,

Gourlie

et al. 2023

Weed Technol

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“…14 Field experiments with quizalofop on resistant wheat varieties reported good control of downy brome, jointed goatgrass, and feral rye, with no crop injury in the tested varieties. 15,16 ALS and ACCase inhibitors have a higher probability of resistance evolution compared to other modes of action based on application frequency and reported cases. 17 These two modes of action are ranked as the first and third for the most resistance cases reported, with 165 and 49 weed species resistant to ALS and ACCase inhibitors, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…This herbicide mode of action is related to fatty acid biosynthesis through inhibition of ACCase 14 . Field experiments with quizalofop on resistant wheat varieties reported good control of downy brome, jointed goatgrass, and feral rye, with no crop injury in the tested varieties 15,16 …”

Section: Introductionmentioning

confidence: 99%

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Survey of ACCase and ALS resistance in winter annual grasses identifies target‐site and nontarget‐site imazamox resistance in Secale cereale

Soni

Westra

Allegretta³

et al. 2022

Pest Management Science

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Background Early detection of herbicide resistance in weeds is crucial for successful implementation of integrated weed management. We conducted a herbicide resistance survey of the winter annual grasses feral rye (Secale cereale), downy brome (Bromus tectorum), and jointed goatgrass (Aegilops cylindrica) from Colorado winter wheat production areas for resistance to imazamox and quizalofop. Results All samples were susceptible to quizalofop. All downy brome and jointed goatgrass samples were susceptible to imazamox. Out of 314 field collected samples, we identified three feral rye populations (named A, B, and C) that were imazamox resistant. Populations B and C had a target‐site mechanism with mutations in the Ser653 residue of the acetolactate synthase (ALS) gene to Asn in B and to Thr in C. Both populations B and C had greatly reduced ALS in vitro enzyme inhibition by imazamox. ALS feral rye protein modeling showed that steric interactions induced by the amino acid substitutions at Ser653 impaired imazamox binding. Individuals from population A had no mutations in the ALS gene. The ALS enzyme from population A was equally sensitive to imazamox as to known susceptible feral rye populations. Imazamox was degraded two times faster in population A compared with a susceptible control. An oxidized imazamox metabolite formed faster in population A and this detoxification reaction was inhibited by malathion. Conclusion Population A has a nontarget‐site mechanism of enhanced imazamox metabolism that may be conferred by cytochrome P450 enzymes. This is the first report of both target‐site and metabolism‐based imazamox resistance in feral rye. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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“…Tolerance is conferred by a target-site resistance mutation in the Acc1 gene (Ala-2004-Val) that results in a single amino acid substitution on the A, B, or D genome. All commercially available varieties have two homologous gene mutations (Hildebrandt 2022). The QPE herbicide inhibits acetyl-CoA carboxylase and provides POST control of many spring and winter annual grasses.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of nonresistant winter wheat to quizalofop-P-ethyl in central Oklahoma and Kansas

Childers

Manuchehri²,

Kumar³

et al. 2022

Weed Technol

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The CoAXium® Production System includes a new herbicide-resistant wheat (AXigen®) that allows for fall and/or spring postemergence (POST) applications of quizalofop-P-ethyl (QPE) for control of winter annual grass weeds. As area planted with AXigen® wheat increases, so will the use of QPE herbicide and with this there is an increased chance for physical drift, tank contamination, or misapplication to nearby sensitive plants. A total of eight field studies were conducted at four locations during the 2018-2019 and 2019-2020 growing seasons to understand the response of non-resistant wheat when exposed to various rates of QPE herbicide. Five rates of QPE were evaluated; 1X (92 g ai ha-1), 1/10X, 1/50X, 1/100X, and 1/200X. Treatments of QPE were applied in the fall (2- to 3-leaf wheat) or in the spring (3- to 4-tiller wheat). Results indicated an interaction between application timing and QPE rate on grain yield for half of the site-years. The 1X rate resulted in complete or near complete grain yield loss regardless of application timing. However, QPE at the 1/10X rate resulted in yield loss ranging from 0 to 41% when fall-applied, whereas spring application resulted in 80 to 100% yield loss. For site-years where only the main effect of QPE rate was significant, 86 to 100% yield loss was observed following exposure to QPE at the 1/10X and 1X rates. For all site years, it was infrequent that significant yield reductions were observed following the three lowest rates of QPE. If the two highest QPE rates were considered to represent tank contamination or misapplication and the three lowest rates physical drift, we can assume that physical drift of QPE to non-AXigen® wheat is not of major concern if proper application guidelines are followed. Conversely, tank contamination and misapplication should be carefully considered by growers who have planted both AXigen® and non-AXigen® wheat varieties.

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Winter annual grass control and crop safety in quizalofop‐resistant wheat cultivars

Cited by 5 publications

References 51 publications

Feral rye (Secale cereale L.) control in quizalofop-resistant winter wheat in Oregon

Feral rye (Secale cereale L.) control in quizalofop-resistant winter wheat in Oregon

Survey of ACCase and ALS resistance in winter annual grasses identifies target‐site and nontarget‐site imazamox resistance in Secale cereale

Sensitivity of nonresistant winter wheat to quizalofop-P-ethyl in central Oklahoma and Kansas

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