Corn that was planted in June should be scouted now for potential damage from black cutworm feeding, says Robert Bellm, University of Illinois Extension crop systems educator. Corn that has five or less fully emerged leaves is at risk if cutworm pressure in a field is high.

"In normal years, black cutworms are not a problem once we get past the first week of June. By then, corn would typically be too large for the cutworm larvae to feed on it," explains Bellm. "This year is an exception, however, because much of the corn in southern Illinois was planted in mid-June and remains small enough to be killed by cutworm feeding."

Black cutworms do not overwinter in Illinois. Instead, the moths are blown into the state on storm fronts in the early spring, starting about the time that corn is normally planted. Multiple new moth introductions can occur throughout the spring as storms pass through. Plus, there may be multiple generations of cutworms produced once moths are present in the area.

Bellm says field scouting should be done as soon as the corn has emerged and continue on a regular basis until the plants have five visible leaf collars. A rescue insecticide treatment may be warranted if 3 percent of plants have been cut and cutworms are still present and actively feeding.

The introduction of insecticide-treated corn seed in the past few years has helped reduce the amount of damage from black cutworm feeding. As a result, growers have gotten out of the habit of scouting fields on a regular basis. Unfortunately, the seed insecticides are not nearly as effective against larger, more developed cutworms as they are on small, newly hatched larvae early in the season.

"Late planted corn, even with an insecticide seed treatment applied, is going to be at risk and should be scouted," advises Bellm. "Crop damage needs to be prevented if at all possible, since it is now too late to replant severely damaged fields."