The annual European corn borer survey for the state is nearly completed for 2007. And at least for our area I feel the need to ask the question 'where have all the refuges gone'?

Each fall, from when the first European corn borer wandered to America and decided to stay, until 1996, University of Illinois Extension conducted a survey of European corn borer infestation in approximately 31 counties across the state. Results were used to attempt to predict activity of first generation European corn borer the next spring. Area Extension Educators and campus staff did the survey. After a 3-year hiatus the fall European corn borer survey was revived in 1999 and continues to aid your pest management decisions for the next year's crop given the current economic situation.

Each year ten random fields are surveyed in evaluated counties, this year again 50 counties and 500 fields in Illinois were surveyed. Data collected includes percentage of infested plants, larval developmental stage and number of corn borers in infested stalks. Based on these data the average number of borers per plant and the percent infestation is calculated for a county. Fields are randomly selected in the counties surveyed with no knowledge if we are examining a Bt field or not.

The average number of corn borers data shows very low potential damage possible for first generation next spring in most of the Eastern crop-reporting district. In Champaign, Iroquois, Vermilion and Macon counties the numbers were extremely low. In fact in Champaign County I only found 1 larva, and as luck would have it, the larva was cut in half when I split the stalk I was evaluating. So in general we should expect a low first generation next spring in our area. Results of the whole survey will soon be posted at http://www.ipm.uiuc.edu/fieldcrops/insects/european_corn_borer/index.html. For spring management, if you select a non-Bt hybrid, remember that earliest planted fields are the most attractive to first generation corn borers. A later planting will reduce infestation. There are effective scouting procedures and treatment thresholds even if a low population is expected.

Even though the corn harvest is not yet over this season very shortly you will need to make a management decision about what kind of seed to purchase for 2008. Should you select a Bt hybrid for European corn borer management next season? You may consider use of a Bt hybrid if borer pressure is expected to be high and you have a history of yield loss from borers. But you might also ponder the question about the amount pressure being exerted on the corn borer population by the extensive use of Bt hybrids.