BromusControl in Winter Wheat (Triticum aestivum) with the Ethylthio Analog of Metribuzin

Abstract

Twenty field experiments were conducted in Oklahoma from 1983 through 1986 to evaluate the ethylthio analog of metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(ethylthio)-1,2,4-triazin-5(4H)-one] for selective control of cheat (Bromus secalinusL. #3BROSE), downy brome (Bromus tectorumL. # BROTE), and rescuegrass (Bromus catharticusVahl. # BROCA) in winter wheat (Triticum aestivumL.). The ethylthio analog of metribuzin applied postemergence at 1.1 kg ai/ha before the weeds tillered controlled 91 to 100% of theseBromusspp. in winter wheat. Control of tilleredBromusspp. was less consistent. AsBromusspp. control increased, wheat yields increased, and dockage decreased. The herbicide was selective on wheat over a wide range of soils, including sands. Adding surfactant to very early postemergence applications of 0.6 kg ai/ha increased cheat control but injured wheat slightly. Surfactant use had little or no effect on dockage reduction and yields.