Twenty-seven sites reporting this week. European corn borer (ECB)-E was caught at five sites with a high of 19 at the Seneca Castle site again. ECB-Z was caught at four sites. Seventeen sites reported corn earworm (CEW), with twelve high enough to be on a 4, 5, or 6 day spray schedule (see table at bottom of post). Fall armyworm (FAW) was caught at ten sites and Western bean cutworm (WBC) was caught at twenty-one sites this week. WBC peaked last week, about two weeks later than previous years and CEW is beginning to increase again (see graph below).

Average sweet corn trap catches for all reporting sites from 5.28.19 – 8.20.19.

Use the table below to determine the estimated WBC flight completion for your site using the Base 38F column. This model is still being validated for NY.

NEWA Western bean cutworm flight emergence lookup table.

Dry Bean Western Bean Cutworm Alert
8.20.19
Marion Zuefle, NYS IPM Program
(Alert modified from Carol McNeil)
(Information and photos from T. Baute, OMAFRA)

This year we are monitoring eight WBC traps placed next to dry bean fields. The location of the traps are given in the image below. Dry bean growers should scout adjacent corn for WBC eggs and larvae when cumulative trap catch reaches 50 moths. Avoca H, Avoca W, South Caledonia, Stafford and Wayland have all reached >50 cumulative moth trap catch and nearby corn should be scouted for egg masses and damage. Peak WBC flight historically occurs the last week of July into early August but seems to be delayed by a few weeks this year. 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 (see image below). Slugs will also feed on the pods causing similar damage, but will often leave a slime trail (image below). 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.

If you have questions contact Marion Zuefle at mez4@cornell.edu or 315-787-2379.

This project is funded by the NYS Dry Bean Industry.

Location of WBC traps near Dry Beans in 2019.