Corn Earworm Alert for Processing Sweet Corn

Corn Earworm Alert for Processing Sweet Corn

Eileen Cullen, Extension Entomologist

The Wisconsin DATCP Wisconsin Pest Bulletin’s Corn Earworm pheromone trap network has registered a significnat and accelerating August corn earworm (CEW) migration flight. As reported in the August 11th issue of WDATCP Pest Bulletin: Large flights of 80-700 moths were registered in Dane and Waushara counties since late July and treatments are underway. Trap counts for the two-week period of July 28-August 10 were: Chippewa Falls 6, Coon Valley 9, Cottage Grove North 120, Cottage Grove South 80, East Troy 1, Hancock 190, Janesville 4, Keyeser 325, Madison North 28, Manitowoc 0, Marshifled 29, Prairie du Chien 6, Sun Prairie North 700, and Wausau 0.

The Wisconsin Pest Bulletin corn earworm pheromone trap network results are updated weekly here under the corn section.

Please Note: The WI DATCP pheromone trap network data above is reported on a weekly, rather than nightly basis. Most cooperators throughout the state check pheromone traps and report numbers weekly. When running a CEW pheromone trap for individual fields or farms, check the trap 2-3 times per week or more often to record moths per night during large flight periods in August for later planted sweet corn.  Insecticide treatment action threshold is based on nightly pheromone trap catpture.

A CEW pheromone trap count of 10 moths for two consecutive nights indicates the need for protective treatment (action threshold) of silking sweet corn fields.

Mike Sandstrom’s ‘InsectForecast’ website provides an excellent forecast and risk assessment for CEW migrations into Wisconsin and the Upper Midwest from overwintering source population areas in the southern region. To view the latest CEW migration risk status for Wisconsin, please visit CEW migration status is currently at Moderate Risk level, one step below the High Risk cateogry.

For additional CEW information and images see: