AMES, Iowa – The implementation of Bt hybrids have allowed a generation of farmers to grow up without having to think about managing for European corn borer. These hybrids have been extremely effective in keeping European corn borer from impacting corn yields, a far cry from the estimated one billion dollars annually the pest was costing farmers in yield losses plus control costs.
Today some farmers, in an effort to lower costs as commodity markets remain low, have started planting corn without the Bt traits that have proven so effective against European corn borer and other caterpillars.
“Use of the Bt traits for corn borers meant that farmers haven’t experienced losses from corn borers in a long time,” said Erin Hodgson, associate professor and extension specialist in entomology at Iowa State University. “People who have started farming in the last 20 years haven’t experienced devastation from corn borers because they’ve had very good control. With some farmers backing off of Bt traits, they are now having questions about the biology, life cycle and management of European corn borer.”
With these pests still active and prevalent, Hodgson authored ISU Extension and Outreach publication “Ecology and management of European corn borer in Iowa field corn” (CROP 3139) to help provide information about the insect to farmers who are encountering it for the first time.
The publication discusses the life cycle, biology and egg laying of European corn borers, as well as the damage an infestation can do to plants and severe yield loss.
How to manage the pest if not using Bt traits in seed is also covered in depth.
“If a farmer decides not to use the traits they will have to incorporate an extensive scouting program,” Hodgson said. “Farmers must be very proactive because it is such a devastating pest. Management must target the eggs and small larvae before they are able to move into the ear. Once they enter the ear there is nothing that can be done. Scouting and quick decision making is very important because the eggs and larvae are exposed for a limited amount of time.”
Worksheets on how to scout and the management decisions that should be made are included in the publication. Also included is a table to track the life cycle of European corn borer based on accumulating degree-days. Degree-days are the average number of degrees above the developmental threshold occurring each 24-hour period.
“We need to have some sort of assessment of adult European corn borer activity,” said Hodgson. “Using degree-days is the most accurate way to track development.”
Photo credit, Merlin Rice