Thirty-two sites reported this week. European corn borer (ECB)- E was caught at three sites and ECB-Z was caught at two sites. The hybrid ECB was caught at three of the six sites trapping for it: Bellona (2), Hurley (4), and Seneca Castle (3). Sixteen sites reported corn earworm (CEW) catches this week with fourteen sites high enough to be on a 4, 5, or 6 day spray schedule (see table at bottom of post). Fall armyworm (FAW) was only caught at nine sites and Western bean cutworm (WBC) was caught at twenty sites.

NEWA Western bean cutworm flight emergence lookup table.

Western bean cutworm numbers are beginning to increase. Peak flight usually occurs around the first week of August. It is important to begin scouting for egg masses even if cumulative trap catches have not reached 50, as egg masses have been found when cumulative trap catched were still in the single digits. WBC will usually lay eggs on the upper side of the top 1-3 leaves of pre-tassel corn, close to the leaf base. After tasseling has finished WBC seek out younger corn or dry beans. To scout for egg masses check the top 3 leaves of ten corn plants in ten locations throughout the field.

It takes between 5-7 days for eggs to hatch. It is critical that sprays are timed before the larvae have a chance to enter the ear. The egg mass will become purple in color approximately 24 hours before egg hatch (see photo).

Interactive Sweet Corn Pheromone Trapping Network Map

Dry Bean Western Bean Cutworm Alert
7.19.22

This year we are monitoring 12 WBC traps placed next to dry bean fields. Dry bean growers should scout adjacent corn for WBC eggs and larvae when cumulative trap catch reaches 50 moths, so far only the LeRoy site has reached 50 cumulative moths. Peak WBC flight historically occurs the first week of August. All dry bean growers should begin scouting pods for WBC feeding about 10 days after peak flight regardless of cumulative trap catch, and should continue to scout for three weeks, especially if damage has been seen in recent years.

Check 10 random spots in a field, 5 plants per spot. Inspect all the pods on the plants looking for holes. Surface feeding can be caused by other insects. WBC will mine directly into the pod and will often feed on the seed inside. European corn borer will also feed inside the pod and would most likely still be present. If there is damage going directly into the pod and seed but no larva present, it is quite possibly WBC. During the day WBC larva are not actively feeding in the pod, instead they drop to the soil and will remain there until night. Fresh damage will be green, not brown.

This project is funded by the NYS Dry Bean Industry.