Quizalofop interactions when mixed with clomazone and pendimethalin in acetyl coenzyme A carboxylase–inhibiting herbicide-resistant rice

A study was conducted in 2017 and 2018 at the H. Rouse Caffey Rice Research Station near Crowley, LA, to evaluate quizalofop at 120 g ai ha−1 applied independently or in a mixture with clomazone, pendimethalin, clomazone plus pendimethalin, or a prepackaged mixture of clomazone plus pendimethalin when PVLO1 rice reached the two- to three-leaf stage. A second application of quizalofop at 120 g ha−1 was applied 21 d after the initial application. At 7 days after treatment (DAT), antagonism of quizalofop occurred when mixed with clomazone at 334 g ai ha−1, clomazone at 334 g ai ha−1 plus pendimethalin at 810 g ai ha−1, or a prepackaged mixture of clomazone plus pendimethalin at 334 plus 810 g ai ha−1, respectively, when applied to barnyardgrass. At 7 DAT, a neutral interaction occurred with a mixture of quizalofop plus pendimethalin at 810 g ha−1. These data indicate the antagonism of quizalofop was overcome at 14, 28, and 42 DAT with a neutral interaction for barnyardgrass control, 94% to 98%, with all herbicide mixtures evaluated. A neutral interaction occurred for CL-111, CLXL-745, and red rice control when treated with all the herbicide mixtures evaluated across all evaluation dates. Rice yield decreased when not treated with the initial quizalofop application.