WEED-CONTROL WITH REDUCED RATES OF 4 SOIL-APPLIED SOYBEAN HERBICIDES

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