Preplanting Applications of Diuron With and Without Trifluralin in Cotton

Preplanting applications of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] with and without trifluralin (a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) were made for 5 years in irrigated cotton (Gossypium hirsutumL.). All treatments containing trifluralin temporarily stunted cotton. In two of the 5 years, trifluralin reduced diuron injury to cotton seedlings which resulted in better crop stands. The trifluralin-diuron combinations resulted in better weed control at harvest than either herbicide alone. The 5-year average yield of cotton was greater with trifluralin-diuron combinations than with the same rates of diuron alone.