Eighteen sites reporting this week. European corn borer (ECB)-E was caught at only 2 sites, Hamlin and Lockport. ECB-Z was caught at 5 sites. Corn earworm (CEW) was caught at six sites this week with Eden, Preble, and Waterport numbers high enough to require a 5 or 6 day spray interval. Only Avon caught fall armyworm (FAW) and no site reported western bean cutworm (WBC) this week.

Several sites reporting ECB larvae and feeding damage in emerging tassels while other sites are already reporting CEW larvae in the silks. The thresholds when scouting differ for these two stages of corn. For tassel emergence corn the threshold is 15% infested plants. As the tassels begin to emerge larvae will leave the tassel and move down the plant looking for protected places to feed.  Insecticide applications need to be timed to kill larvae before they bore into a new feeding location where they will be protected from sprays. For silking corn the threshold drops to 5% infested plants. Scout the ear zone, two leaves above and one leaf below the ears, for ECB egg masses and ECB or FAW larvae. For more information on how to scout both tassel emerging and silking corn please see the video: How to Scout Fresh Market Sweet Corn Video.

J.W. Apple, Department of Entomology, University of Wisconsin-Madison