Field assessment of flazasulfuron and trifloxysulfuron sodium drift

Exposure of non-target species pesticide via drift is concern to the United States Environmental Protection Agency (EPA) as evidenced by required buffer zones and language on labels regarding offsite exposure endangered species. In 2008, flazasulfuron received a conditional registration that specified 30-m nontreated between treated areas sensitive plants. This would make most intended uses in warm-season turfgrass impossible. Assessment field conditions replace model-predicted restrictions. Studies were conducted assess similar herbicide, trifloxysulfuron sodium, using conventional spray equipment maximum boom height minimum droplet size product labels. Herbicides applied perpendicular 6.4 9.7 km h−1 wind over ‘Riviera’ bermudagrass [Cynodon dactylon (L.) Pers.] turf sentinel corn plants placed at distances 0 30.5 m downwind. A bioassay based reduction growth rate shoot biomass indicated sodium reduced similarly but magnitude these effects dependent year. Year dependency was likely associated with differences cultivars years. Herbicide not detected beyond 4.6 downwind any application. Upon reviewing other data, EPA approved label modification for 7.6 m.