Rice tolerance to multiple applications of florpyrauxifen-benzyl alone and followed by benzobicyclon

Abstract

Varying levels of sensitivity to florpyrauxifen-benzyl and benzobicyclon applications among rice (Oryza sativa L.) cultivars have been observed. The safe use of florpyrauxifen-benzyl and benzobicyclon in the same herbicide program could provide broad-spectrum weed control and delay resistance in weed species. Two experiments were conducted in 2019 and 2020 near Stuttgart, AR, to test cultivars’ sensitivity to multiple rates of florpyrauxifen-benzyl and applications of florpyrauxifen-benzyl followed by benzobicyclon. The first experiment was designed to determine the sensitivity of the rice cultivars ‘XP753’, ‘CL XL745’, ‘Gemini 214CL’, ‘Titan’, and ‘Diamond’ to applications of florpyrauxifen-benzyl at 0.03 and 0.06 lb acid equivalent (a.e.) acre–1 and sequential applications of 0.03 lb a.e. acre–1. The second experiment determined the effect of benzobicyclon applied post-flood on rice injury following an application of florpyrauxifen-benzyl on the same cultivars used in the previous experiment. A rough rice yield loss of 17% was observed for sequential applications of florpyrauxifen-benzyl at 0.03 lb a.e. acre–1 to XP753. Single applications of florpyrauxifen-benzyl at 0.06 lb a.e. acre–1 caused a 45% groundcover reduction in XP753, whereas sequential applications of 0.03 lb a.e. acre–1 reduced groundcover on all hybrid cultivars tested. Applications of benzobicyclon alone never injured rice by more than 8%, and applying benzobicyclon after florpyrauxifen-benzyl did not increase the observed injury over florpyrauxifen-benzyl alone. Single applications of florpyrauxifen-benzyl followed by benzobicyclon can be used in an herbicide program to control weeds without the risk of greater injury than is typically caused by florpyrauxifen-benzyl alone.