Cover crop and nitrogen fertility effects on southern corn rootworm (Coleoptera: Chrysomelidae) damage in corn

The effect of winter legume and grass cover crops, nitrogen fertility, and insecticide use on seedling injury by the southern corn rootworm, Diabrotica undecimpunctata howardi Barber, was investigated in no-tillage field corn, Zea mays L. Rootworm injury was most severe following hairy vetch, Vicia villosa Roth, and least severe following no cover crop (fallow). Injury after wheat, Triticum aestivum L.; rye, Secale cereale L.; or crimson clover, Trifolium incarnatum L., was intermediate compared with injury after vetch and fallow. Rootworm injury following vetch reduced corn stand by ≥50% compared with fallow in all years. Corn plant stand was not different between cover-crop treatments when terbufos insecticide was applied at planting, indicating that cover-crop treatments did not affect corn stand establishment directly. Despite reductions in plant population, remaining plants compensated by producing more ears and grain weight per plant, which resulted in little reduction in corn yield in all cover-crop treatments except after vetch. Nitrogen fertility did not affect stand loss and plant injury by the southern com rootworm, and corn yield response to nitrogen fertility was not affected by rootworm control with a soil insecticide. Use of legume cover crops, especially hairy vetch, to prevent soil erosion over the winter and provide a source of nitrogen may enhance the pest status of the southern com rootworm in no-tillage com production in the southeastern United States.