Not much is said by entomologists or in the press about European corn borer these days. It was always more of a consistent year-to-year pest in the western Corn Belt, and only an occasional pest in certain years in Indiana. With the advent of Bt corn in the 1990's, not many people worry about it anymore.
Danny Greene, of Greene's Crop Consulting, Inc., Franklin, believes that might be a mistake if you have no-GMO corn. Recent scouting in a field to pull stalk samples for nitrogen analysis seemed to indicate he might be right.
"The GMO events we have for corn borer are very effective, so if you plant Bt corn with corn borer protection you won't see much," he says. "However, by what we're seeing in non-GMO fields, it appears this was a pretty good year for corn borer. It may have paid to have treated some of those fields earlier in the season."
The trouble with scouting and treating for corn borer is catching borers at the right stage where they are still vulnerable to spray. It's often hard to time the application to get effective kill of corn borer larvae.
Greene first began noticing the effects of corn borer damage in non-GMO corn when he placed the 12 stalk samples cut from various locations in bags and putt he bags side-by-side. Bags from non-GMO fields often contained one or more stalks with a significant amount of the stalk tissue missing. In almost all cases he says it was because corn borers had tunneled through the pith earlier in the season. The stalks had lost some vascular tissue, which means they could no longer be as efficient at moving water and nutrients up the plant or carrying sugars down to the roots.
The stalks affected by corn borer seemed more likely to collapse more easily when pressed together, he added.