Bt corn and stalk rots
Stalk rots are among the most serious diseases of corn, causing yield loss through reduced grain fill, premature death, and lodging. Because of the interactions between stalk-boring insects and stalk rot fungi, Bt hybrids have the potential to provide a side benefit in terms of reduced stalk rot. But stalk rot fungi enter corn plants through several different pathways, so the influence of European corn borers on stalk rot can range from none to great, depending on the specific field conditions. For the last 2 years we have evaluated stalk rot in Bt hybrids and near-isogenic non-Bt hybrids in Ames and other locations. In December, Dale Farnham reported yield performance for Bt hybrid trials conducted with ISU Extension field specialists throughout the state. In several of those locations, data also were collected on stalk rot. Corn borer infestations in those plots were naturally occurring and were not severe.