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