Weed Control With Reduced Rates of Four Soil Applied Soybean Herbicides

Abstract

Field studies were conducted at two locations in Missouri in 1990 and 1991 to evaluate control of velvetleaf, ivyleaf morningglory, and cocklebur in soybean with label rates (1×) or reduced rates (0.5×) of four PPI herbicides followed with or without cultivation and POST application of one fourth (0.25×) the label rate of imazethapyr. Weed control and soybean yield with the 0.5× rate of preplant clomazone, imazaquin, metribuzin, and metribuzin + chlorimuron followed by either cultivation or imazethapyr POST was equivalent to a 1× rate of the PPI herbicides followed by either cultivation or imazethapyr. Weed control and soybean yield with the 0.5× rates of the PPI herbicides without cultivation or POST imazethapyr were lower than with 1× rates of PPI herbicides.