TIMING OF PLOWING AND PLANTING - EFFECTS ON SEEDCORN MAGGOT POPULATIONS IN SOYBEAN

Seedcorn maggots (Delia platura Meigen) are occasional pests of corn a nd soybean, especially in the Midwest region of the USA. A 2-year fiel d study demonstrated that the presence and emergence of adult seedcorn maggots were governed by timing of tillage operations. Two distinct s eedcorn maggot cohorts were recorded each year, one following an early plowing and another after a late plowing. Peak emergence of adult fli es occurred following the accumulation of Ca 408 thermal units. Simila r trends in adult emergence were observed from plots with and without soybeans. A large population of seedcorn maggots during the second yea r reduced plant stand, but no seed yield differences were obtained.