Bugeye workshop: Cutworms and kin

February 2, 2019

Cutworm numbers have been on the increase in western Nebraska over the past several years, and the damage they can cause to dry edible bean fields has bean growers and others in the industry concerned.

Luckily, it is not too difficult or too expensive to control cutworms. But effective control depends on applying insecticide at the right time. And knowing the right time is a matter of monitoring populations of cutworm moths, which lay the eggs that produce the cutworms.

A hands-on workshop scheduled for early March is designed to train people to identify cutworms from all the other moths, and show how to monitor populations. It is organized by UNL Extension Entomologist Jeff Bradshaw, based at the Panhandle Research and Extension Center in Scottsbluff.

“Bugeye Workshop: Cutworms and Kin” will take place on March 11, with one session at 9 a.m. and a repeat session at 2 p.m. It will be in the Bluestem Room of the Panhandle Center. Attendance is limited to 15 people per session, 30 total. Register only at https://go.unl.edu/bugeye

For more information call 308-632-1230.

Bradshaw said conversations with dry bean growers and processors have made him aware of concerns about increasing cutworm numbers, and the associated damage in dry bean fields. Cutworm numbers tend to be cyclical, but their increase is possibly related to weather or climate, according to Bradshaw. The past few winters have been relatively mild in western Nebraska.

The cutworm workshop will be the first in what is planned to be a series of hands-on events designed to train people in the practical identification of insects important to agriculture and natural resources, Bradshaw said. Each workshop will focuses on a different group of insects.

Although “Bugeye” is a fun title for the series, Bradshaw says jokingly that workshop participants will spend some time looking at the moths through microscopes and might become temporarily bug-eyed themselves. The workshop is intended to teach:

• The diversity of cutworm moths common to the Nebraska Panhandle;

• The role of cutworm moths in our agroecosystems;

• How to identify common cutworm moths and larvae;

• The proper setup, deployment, and sampling of cutworm moths, with special focus on the western bean cutworm in dry bean and corn.

There is no fee to participants, but the event is made possible by several sponsors, including Trinidad Benham Corp., Kelley Bean Company, and a grant from the U.S. Department of Agriculture National Institute of Food and Agriculture (USDA-NIFA). Bradshaw said the target audience is crop consultants, field scouts, and agriculturalists.

In order to control damage from cutworms, farmers need to not only be able to identifying cutworm moths, but also determine the best time to apply treatment. Bradshaw says timely management is critical to preventing crop damage.

Applying insecticide when the population is at its peak is most effective, and applying either too early or two late might be costly in several ways.

Applying chemicals too early can result in a “double whammy,” according to Bradshaw. “You might not have needed to spend the per-acre cost to apply insecticide in the first place, and in addition some insecticides may reduce natural enemies, compounding the problem.”

Monitoring the local cutworm moth population is important, he stressed. Keeping track of populations allows farmers to know whether they have crossed a threshold determining whether the risk of infestation is high or low.

Cutworm moth populations generally peak in July, and 10 to 20 days following the peak population is the sweet spot for treatment, according to Bradshaw.

The March workshop will cover monitoring technologies, Bradshaw said. Trapping systems have been used for years, but now there are also newer trapping systems that count the moths automatically.

Bradshaw hopes the workshop also serves as a training event for a monitoring network that he hopes to establish, using the modern traps.

Future topics in the Bugeye workshops will depend on the need and interest. One possible topic under consideration, Bradshaw said, is beneficial insects.

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