Development of an Economic Injury Level for European Corn Borer (Lepidoptera: Pyralidae) on Corn Grown for Silage

Abstract

Studies were conducted in 1996 and 1997 at 2 locations in Wisconsin to assess the impact of European corn borer, Ostrinia nubilalis (Hubner), on corn grown for silage. Relationships between silage yield losses and control costs were used to develop economic injury levels specific to corn grown for silage in Wisconsin. Treatments were established as the percentage of plants infested with European corn borers. Treatment levels of 0, 12, 24, 40, and 84% of plants infested were used to separately examine simulations of 1st- and 2nd-generation European corn borer infestations. Experiments were performed using Pioneer dual purpose hybrids 3394 and 3751. Results from experiments showed that overall whole plant dry matter yields for 3394 were 8.5% > 3751 across the 3 experiments. Increasing European corn borer infestation proved to be highly correlated with a decrease in both whole plant and stover silage yields throughout experiments, hybrids, and simulated European corn borer generations. Differences in the rates of yield reduction were not seen between the 2 hybrids, however simulations of 1st-generation European corn borer infestation caused greater reductions than did simulations of 2nd-generation European corn borers. Linear regression models proved to best fit the yield loss relationships and were developed to describe silage yield losses resulting from European corn borer infestations. Economic injury levels were determined by comparing silage yield reductions and associated monetary losses with control costs. Economic injury levels were calculated separately for both 1st- and 2nd-generation European corn borers.