Both races of European corn borer are being caught this week, with numbers remaining in the single digits.  Corn earworm was caught at about half the trap locations this week, with highest catches at 5 moths occurring at three locations.  Fall armyworm made an appearance this week, at six locations, with a high count of 13 moths.  Western bean cutworm numbers are increasing gradually, and do not appear to have peaked yet.

True armyworm were found in high numbers in a grass hay field in western NY this week.  Keep an eye on late sweet corn plantings, especially those near hay or grass fields.  In Ontario, a threshold of 10% infested plants is being recommended at the seedling stage, and 50% at the mid-whorl stage.  True armyworm may also appear in the emerging tassel, causing damage similar to fall armyworm.

Scout tassel emergence and silk stage fields for European corn borer and fall and true armyworm larvae emerging with the tassel, and ECB egg masses and newly hatched larvae in the ear zone.  The treatment threshold is 15% infested plants in tassel emergence stage fields, and 5% in silk stage fields.  Where corn earworm are being caught, time applications in green silk stage fields by trap catch numbers in the table below.  Trap numbers this week are indicating the need for a 5-6 day spray interval where CEW are being caught.

Trap catches for the week of 7/10-17/12