Evaluation of sequential applications of quizalofop-p-ethyl and propanil plus thiobencarb in acetyl-coA carboxylase inhibitor–resistant rice

Abstract

AbstractA field study was conducted in 2015 and 2016 at the H. Rouse Caffey Rice Research Station near Crowley, Louisiana, to evaluate the interactions of quizalofop and a mixture of propanil plus thiobencarb applied sequentially or mixed to control weedy rice and barnyardgrass. Visual weed control evaluations occurred at 14, 28, and 42 d after treatment (DAT). Quizalofop was applied at 120 g ai ha−1 at 7, 3, and 1 d before and after propanil plus thiobencarb were each applied at 3,360 g ai ha−1. In addition, quizalofop was applied alone and in a mixture with propanil plus thiobencarb at day 0. Control of red rice ‘CL-111’ and ‘CLXL-745’ was greater than 91% when quizalofop was applied alone at day 0, similar to control for quizalofop applied 7, 3, and 1 d prior to propanil plus thiobencarb at all evaluation dates. Control of the same weeds treated with quizalofop plus propanil plus thiobencarb applied in a mixture at day 0 was 70% to 76% at each evaluation date, similar to quizalofop applied 1 or 3 d after propanil plus thiobencarb. A similar trend in control of barnyardgrass by 88% to 97% occurred when quizalofop was applied alone and by 48% to 53% at 14, 28, and 42 DAT when the mixture was used. ‘PVL01’ rough rice yield was 4,060 kg ha−1 when treated with quizalofop alone; however, yield was reduced to 3,180 kg ha−1 when it was treated with quizalofop mixed with propanil plus thiobencarb at day 0, similar to PVL01 rice treated with quizalofop 1 or 3 d following the propanil plus thiobencarb application.