Twenty-one sites reported this week for Western NY. European corn borer (ECB)-E was caught at three sites with two sites showing a marked increase, Batavia and Kirkville. ECB-Z was also caught at three sites but remains in the single digits. Corn earworm (CEW) reported at three sites with the Belfast site high enough to require a 6 day spray schedule. Fall armyworm (FAW) was caught at five sites and seven sites reported Western bean cutworm (WBC) this week.

In addition to the Western sites, twelve of the thirteen Eastern sites reported this week. Please see the bottom of this post for a table of trap catches from Eastern NY. To view the locations of the Eastern sites please see the map located on the About page.

Fall armyworm and Western bean cutworm numbers are beginning to increase. When scouting sweet corn look for FAW egg masses on the leaves. Egg masses consist of 50-150 eggs and can be distinguished from ECB by the fine hairs covering the egg mass. Feeding damage is also very different from ECB. FAW will cause ragged feeding damage on leaves with large amounts of frass below the feeding site. The larva has a distinct inverted ‘Y’ on the front of the head.

For WBC it is recommended that all fields that are in the whorl or early tassel stage be scouted for egg masses with a 4% threshold for processing sweet corn and a 1% threshold for fresh market sweet corn. 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.

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).