Common waterhemp (Amaranthus rudis Sauer) management with soil-applied herbicides in soybean (Glycine max (L.) Merr.)

Amaranthus rudis can exhibit multiple emergence events during a crop growing season. Control of this species in soybean with soil-applied herbicides can be variable. A 2-yr field research project was conducted to examine the influence of herbicide application timing and dose on efficacy of six soil-applied herbicides for common waterhemp control in soybean. Four weeks after soybean planting, herbicides applied preemergence provided 18% greater common waterhemp control than when herbicides were applied 5 weeks early preplant. Herbicide dose did not significantly influence common waterhemp control, but differences among the six herbicides were evident. Sulfentrazone controlled common waterhemp better and reduced its density more than other herbicides. All herbicides reduced the weed density and dry weight more than the nontreated control.