Published online by Cambridge University Press: 12 June 2017
Combinations of herbicides applied preemergence and postemergence, with and without cultivation, were evaluated for their effectiveness for controlling weeds in soybeans [Glycine max (L.) Merr. ‘Williams’]. Annual weeds were controlled best when a sequential treatment of a mixture of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] + linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] was applied preemergence, and glyphosate [N-(phosphonomethyl)glycine] was applied postemergence, followed by one cultivation. The largest soybean yields were obtained when alachlor + linuron applied preemergence was followed by a cultivation, bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] applied postemergence, bentazon applied postemergence and a cultivation, or glyphosate applied postemergence and a cultivation. Regression analysis of the soybean yield vs. weed control data for all treatments indicated that soybean yields were suppressed an average of 180 kg/ha when glyphosate was applied postemergence. A cultivation in addition to the preemergence and postemergence treatments improved both weed control and soybean yield.