Field studies were conducted in 1991 and 1992 to determine potential soybean injury due to 2,4-D ester at 560, 1120, and 1680 g ai/ha applied 0, 7, and 14 d before planting (DBP). Delayed emergence and increased injury of soybean were observed as 2,4-D rate increased and interval between application and planting decreased. Delay in emergence ranged from 0 to 67% and 0 to 50% in 1991 and 1992, respectively. Injury at 15 days after planting (DAP) combined over years ranged from 0 to 61%. Minimal (0 to 8%) delay in emergence and minimal (0 to 5%) injury at 15, 30, 45, and 60 DAP occurred when 2,4-D at 560 or 1120 g/ha was applied 7 or 14 DBP. No significant yield reduction occurred due to 2,4-D rate, application timing, or their interaction.

Soybean response to simulated drift of the corn herbicides nicosulfuron and primisulfuron applied POST at 10 to 50% (3.5 to 17.4 and 4.0 to 20.2 g ai ha−1, respectively) of the total rates at the V3 and R1 growth stages was evaluated in field studies in 1991 and 1992. Primisulfuron reduced soybean height and increased leaf chlorosis, cupping, and necrosis more than nicosulfuron with both applications at all five rates. The symptoms of injury caused by both herbicides often increased linearly with increasing rate. At 50% of label rate, primisulfuron reduced height 75% and decreased yield 58%. Nicosulfuron reduced soybean height 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.