Tillage, Nitrogen Timing, and Planting Date Effects on Western Corn Rootworm Injury to Corn

Abstract

AbstractThe western corn rootworm (WCR) (Diabrotica virgifera virgifera Le‐Conte) has become a serious pest of continuous corn (Zea mays L.) in the northeastern USA. Several recommended crop production practices in this area, such as early planting, sidedressing N applications, and no‐till, often contribute to slow early‐season growth, which could affect the potential for damage from the WCR. The objective of this study was to determine if these practices affected root damage ratings or yield reductions associated with the WCR. Field experiments were conducted in 1991, 1992, and 1993 on well‐drained Hagerstown silt loam soils (fine, mixed, mesic Typic Hapludalfs). Treatments in each study were factorial combinations of two tillage treatments( nonea nd chisel‐disk), three timings of N fertilizer application (at planting, sidedressed, or split), two planting dates (early and late May), and two insecticide treatments (none and 1.12 kg ha−1 chlorpyrifos). Each treatment was replicated four times. Lodging, root damage ratings, root dry matter estimates, and grain and silage yields were measured for each treatment. Root damage ratings were not affected by the planting date, N timing, or the tillage system. Insecticide had a large and consistent effect on reducing root damage from the WCR. Root size estimates indicates that late planting reduced root size but did not affect root damage. These results indicate that reduced tillage, N sidedressing, and early planting can be included in an integrated pest management program with no risk of increasing the potential for root damage from the western corn rootworm.