Johnsongrass (Sorghum halepense) Control in Reduced-Tillage Systems

Fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)benzenamine], pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], and trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine] either alone or in combination with fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy] propanoic acid}, haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, or sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} were evaluated for johnsongrass [Sorghum halepense(L.) Pers. # SORHA] control in reduced-tillage soybean [Glycine max(L.) Merr.] production systems. Data obtained in 1983 and 1984 near Lexington and Princeton, KY, indicated that johnsongrass could be effectively controlled. A single discing before application of the soil-active herbicides usually had no effect on johnsongrass control. Johnsongrass control was primarily dependent on foliarly applied herbicides. Preplant-incorporated treatments did not provide adequate johnsongrass control when used alone. Johnsongrass panicle numbers recorded in September corresponded to visual evaluations of control recorded earlier in the growing season. Soybean yield with all herbicide treatments was greater than with a nontreated control and was closely associated with the degree of johnsongrass control.