Persistence of rimsulfuron on perennial ryegrass (Lolium perentre) and annual bluegrass (Poa annua) foliage

Field studies have shown that rimsulfuron can move laterally with mower tires and injure neighboring cool-season grasses, indicating that persistent chemical can dislodge from turfgrass foliage. Laboratory studies were conducted to evaluate persistence and stability of C-14 rimsulfuron on perennial ryegrass and annual bluegrass foliage. Rimsulfuron was absorbed by annual bluegrass and perennial ryegrass equivalently, and persisted equally on foliage of each species. When extracted with a water rinse, 57% of applied rimsulfuron was recovered after 10 min, and 42% of applied rimsulfuron was recovered after 96 h. Rimsulfuron was stable 4 d after application based on comparison. of rinse water chromatograms to stock solution chromatograms. These data indicate that appreciable rimsulfuron persists on turf foliage for 4 d. Thus, limiting traffic on treated areas for several hours to allow drying is not a viable method to prevent lateral relocation of rimsulfuron, and subsequent injury to cool-season turfgrasses.