SOYBEAN (GLYCINE-MAX) TOLERANCE TO SIMULATED DRIFT OF NICOSULFURON AND PRIMISULFURON

Soybean response to simulated drift of the com herbicides nicosulfuron and primisulfuron applied POST at 10 to 50% (3.5 to 17.4 and 4.0 to 2 0.2 g ai ha-1, respectively) of the total rates at the V3 and R1 growt h stages was evaluated in field studies in 1991 and 1992. Primisulfuro n reduced soybean height and increased leaf chlorosis, cupping, and ne crosis more than nicosulfuron with both applications at all five rates . The symptoms of injury caused by both herbicides often increased lin early with increasing rate. At 50% of label rate, primisulfuron reduce d height 75% and decreased yield 58%. Nicosulfuron reduced soybean hei ght as much as 27%, but did not reduce seed yield either year. Height reduction, leaf chlorosis, cupping, and necrosis were correlated with yield loss caused by primisulfuron.