Twenty-nine sites reporting this week. European corn borer (ECB)-E was caught at eight sites with a high of 41 at the Seneca Castle site again. ECB-Z was caught at six sites. Eleven sites reported corn earworm (CEW), with all of them 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 eight sites and Western bean cutworm (WBC) was caught at twenty-five sites this week.

WBC catches were up again this week. Peak flight usually occurs the last week of July into the first week of August but this year it seems to be delayed by at least a couple of weeks. This is also what is reported from Ontario, Canada. The graph below shows average trap catch for the 5 different moths to date, the yellow line is WBC.

Average sweet corn trap catches for all reporting sites from 5.28.19 – 8.13.19.

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.

One of the fields I scouted this week had aphids near threshold. This is a good time to look for corn leaf aphids, record the number of plants with more than 50 aphids. The threshold for corn leaf aphid at tassel emergence is 50% of plants with more than 50 aphids.

Corn leaf aphids on emerging tassel.

Dry Bean Western Bean Cutworm Alert
8.13.19
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.