Western Bean Cutworm Management

Bryan Jensen, UW Extension and IPM Program

Although this article may seem premature, the warm weather has gotten me thinking about those insects which could be favored by the abnormally high winter temperatures. Western bean cutworm (WBC) is one insect on that list. What also prompted this article is that several states in the Great Lakes Region and Ontario have reported high populations of WBC last year as well as WBC related performance issues with the Cry1F protein. Please consult the Handy Bt Trait Table authored by Michigan State University Extension Entomologist, Dr. Chris DiFonzo, for those trait families which incorporate the Cry1F protein.

WDATCP’s Wisconsin Pest Bulletin also reported a moderate increase in moths/trap last year after three consecutive years of low numbers. Equally important was their survey personnel indicated finding larval damage in both traited and non-traited corn. Although the incidence of larval damage seems to be lower in Wisconsin than the previously mentioned states it does make you wonder what will happen during the 2017 growing season, if anything.

To date, I have not heard of any western bean cutworm performance issues from those corn hybrids which incorporate the Vip3A protein (which also targets black cutworm, stalk borer, true armyworm but not European corn borer). However, it is still worth some effort to monitor those fields and error on the side of caution. For those fields without an above ground trait, which have a trait that does not target WBC and for those hybrids which include the Cry1F trait, field monitoring is highly suggested. Especially if you observed WBC damage in 2016. Plan to initiate scouting at approximately 1320 degree days (accumulated DD will be published in the Pest Survey Bulletin, subscribe). Please continue to watch future issues of the Wisconsin Pest Bulletin and Wisconsin Crop Manager for updates during the growing season. Please feel free to offer your comments and/or observations to me via email.