First-generation European corn borer (Lepidoptera: Pyralidae) response to three conservation tillage systems in Minnesota

Plant injury and densities of mature larvae by first-generation Ostrinia nubilalis (Hubner), European corn borer, were examined in chisel-plow, ridge-tillage, and no-tillage maize, Zea mays (L.), in southeastern Minnesota during 1985-1987. Tillage plots were split with and without terbufos application and with and without Bacillus thuringiensis-permethrin application in all combinations. Chisel-plow suffered greater plant injury than ridge-tillage or no-tillage, probably because oviposition was greater in chisel-plow. Ovipositing females were not responding primarily to plant height or developmental stage. Soil surface temperatures were higher in chisel-plow during the early evening when oviposition occurred, and we suggest microclimate influenced female oviposition. Larval density was highest in chisel-plow maize that received terbufos. We concluded that the risk of yield loss to first-generation O. nubilalis in ridge-tillage and no-tillage maize did not exceed the risk of yield loss in chisel-plow maize