Non-selective and Selective Herbicide Combinations in Stale Seedbed (Glycine max)

Abstract

Field experiments were established in 1991 and 1992 on silty clay and sandy loam soils to evaluate combinations of non-selective and selective herbicides for stale seedbed soybean weed control. Metribuzin PRE controlled sicklepod and pitted morningglory more consistently than other treatments. At 9 wk after planting, antagonism occurred in most cases on sicklepod control when metribuzin was tank-mixed with a non-selective herbicide. Other selective herbicides required addition of a non-selective herbicide at planting to effectively control sicklepod and pitted morningglory. Sicklepod and pitted morningglory control was better with POST selective herbicides when following glufosinate or paraquat than when following glyphosate or SC-0224. In most instances a follow-up POST treatment was needed to maintain weed control from non-selective herbicides applied PRE. Metribuzin and metribuzin plus chlorimuron increased soybean yields when tank-mixed with paraquat compared with yields obtained with paraquat alone.