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 14C 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.
Nomenclature: Rimsulfuron; annual bluegrass, Poa annua L. #3 POAAN; perennial ryegrass, Lolium perenne L. ‘Pennant II’.
Additional index words: Absorption; herbicide degradation; herbicide relocation; herbicide stability; sulfonylurea.
Abbreviations: HAT, hours after treatment; LSS, liquid scintillation spectrometry; TLC, thin-layer chromatography.