Preemergence Japanese stiltgrass control in turfgrass

Plain Language Summary Japanese stiltgrass is an emerging problem in turfgrass management. Although preemergence control of Japanese stiltgrass has not been reported, several turfgrass managers have observed no control of Japanese stiltgrass with preemergence herbicides traditionally used to control other summer annual grass weeds. We evaluated three common turfgrass preemergence herbicides for the control of Japanese stiltgrass. These herbicides were very effective, although prodiamine was slightly less effective than pendimethalin and dithiopyr. Herbicides applied at half the standard rate were less effective than those applied at the standard rate or in sequential applications. Results suggest that preemergence herbicides commonly used for annual grass control in turfgrass are also effective against Japanese stiltgrass. However, these herbicides must be applied before Japanese stiltgrass germinates, which is likely 2–4 weeks earlier than they are commonly applied to control other summer annual grasses, such as crabgrass.