Influence of Simulated Rainfall on Large Crabgrass Control with Two Quinclorac-Containing Herbicides

L arge crabgrass (Digitaria sanguinalis) is a common turfgrass weed throughout the transition zone and southern United States (1). Herbicides containing the active ingredient quinclorac are oten used for selective large crabgrass control. Quinclorac is sold alone under the trade name Drive XLR8 and is labeled for postemergence large crabgrass control in several warmand cool-season turfgrasses. Solitare is a 3:1 mixture of quinclorac and sulfentrazone also labeled for large crabgrass control. Rainfall can reduce eicacy of postemergence herbicides by washing spray solution from leaf surfaces before absorption and entry into the plant. Current labeling for both Drive XLR8 and Solitare indicates that foliage must remain dry for 24 h ater application. However, quinclorac has been shown to enter susceptible weeds through both foliar and root tissue (2). hus, rainfall within this 24-hour period may not negatively afect eicacy, providing turf managers a greater window of opportunity to make applications for large crabgrass control. herefore, our objective was to evaluate efects of simulated rainfall timing on the eicacy of Drive XLR8 and Solitare for large crabgrass control.