Question: How late in the season do I need to check for black cutworms?
Answer: Don’t go by time of season as a lot of corn was planted late this year. Better yet, scout emerged corn weekly for black cutworm damage until the crop reaches the V5 growth stage. Check corn plants in four or five areas with each field. Problem signs are plant wilting, leaf discoloration and damage as well as missing and cut plants, not to mention the pest itself. If larvae found in the field are smaller than 3/4 of an inch, then a rescue insecticide is warranted if 2% to 3% of plants are wilted or cut. If larvae are larger than 3/4 of an inch, the threshold increases to 5% cut plants. Due to the high market price of corn and fluctuations in inputs, Iowa State University has a dynamic action threshold. The action threshold calculation determines when it is economical to treat for BCW based on plant population, expected yield, anticipated market value, and the cost of control:
Time to Scout for Cutworms
It’s prime time to be walking corn fields. Be on alert for cutworms. It’s prime time to be walking corn fields, says Jim Jarman, University of Missouri agronomy specialist.
What You Need to Know about Black Cutworms
As corn begins emerging across the Corn Belt, unseasonably warm weather has farmers on high alert for black cutworms, and accurate scouting is a must.