Managing emerged weeds that have evolved resistance to herbicides is a challenging task. Dose-response experiments were performed to investigate the sensitivity of one susceptible and three putative resistant (R1, R2, and R3) barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] biotypes to florpyrauxifen-benzyl and cyhalofop-butyl alone and as a formulated premix. Absorption, translocation, and metabolism of florpyrauxifen-benzyl in the biotypes following application of florpyrauxifen-benzyl alone and in a premix with cyhalofop-butyl were also evaluated to unravel the potential resistance mechanism. Resistance/susceptibility ratios for R1 (7.0−50), R2 (7.0−150), and R3 (18−214) biotypes were obtained based on dose-response experiment results. Reduction in absorption and translocation of [14C]-florpyrauxifen-benzyl was observed in R1 and R3 biotypes. The production of the active form metabolite [14C]-florpyrauxifen-acid following florpyrauxifen-benzyl alone was &gt;2-fold less in resistant biotypes (9−11%) than in the susceptible biotype (23%), and its production in susceptible barnyardgrass (not in the R biotypes) increased 3-fold when florpyrauxifen-benzyl was applied in mixture with cyhalofop-butyl. The overall results of this study show that resistance of barnyardgrass to florpyrauxifen-benzyl can be associated with mechanisms causing reduced conversion or rapid degradation of florpyrauxifen-acid along with reduced absorption and translocation of the herbicide.

Absorption, translocation, and metabolism of florpyrauxifen-benzyl in cyhalofop-butyl-resistant barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.]

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.