INFLUENCE OF COVER CROPS AND TILLAGE ON SEEDCORN MAGGOT (DIPTERA, ANTHOMYIIDAE) POPULATIONS IN SOYBEANS

The effects of cover crops and crop residues on seedcom maggot, Delia platura (Meigen), population dynamics in soybeans (Glycine max Merrill) were studied when incorporated into the soil before crop planting and when left on the soil surface where soybeans are planted, using no-tillage practices. Crop covers and residues had a dramatic effect on seedcorn maggot populations; highest numbers were obtained when cover crops were incorporated. When no-tillage planting methods were used, no enhancement of populations was obtained. Significantly greater numbers of D. Platura adults were obtained from plots where alfalfa (Medicago sativa L.) was incorporated into the soil, followed by rye (Secale cereale (L.)), soybean residue, and least with corn (Zea mays L.) residue. Orthogonal comparisons indicated that more seedcom maggots were obtained when a live, green cover was incorporated into the soil than with dead crop residue. Orthogonal comparisons also showed that more adults were collected when a legume was incorporated compared with a grass. © 1990 Entomological Society of America.