SOYBEAN (GLYCINE-MAX) TOLERANCE TO 2,4-D ESTER APPLIED PREPLANT

Field studies were conducted in 1991 and 1992 to determine potential s oybean injury due to 2,4-D ester at 560, 1120, and 1680 g ai/ha applie d 0, 7, and 14 d before planting (DBP). Delayed emergence and increase d 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 app lied 7 or 14 DBP. No significant yield reduction occurred due to 2,4-D rate, application timing, or their interaction.