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.