By Scout Nelson
Dingy cutworms have been observed in no-till soybean fields across South Dakota, creating concerns for farmers during the growing season. These insects usually are not major pests, but large populations can damage soybean, corn, and wheat by feeding on leaves and cutting young plants. Their activity is expected to continue for at least the next couple of weeks, making regular field scouting an important step for protecting crops.
Adam Varenhorst, Associate Professor and SDSU Extension Field Crop Entomologist, along with Patrick Wagner, Philip Rozeboom, Amanda Bachmann, and Shelby Pritchard, highlighted the importance of monitoring fields early to prevent serious stand losses. Their work encourages producers to identify infestations quickly and make management decisions before crop damage becomes severe.
Dingy cutworms are most common in no-till fields or areas with large amounts of crop residue. They are also more likely to appear in fields with reduced tillage, poor drainage, or where weeds and cover crops were present before planting. The caterpillars feed mostly at night and hide in the soil during the day, making them difficult to detect without careful scouting.
The caterpillars are dull brown to gray with a pale gray stripe running down the middle of the body. They also have small spots of similar size along each body segment and two dark lines on their brown head. Farmers can often find them by digging one to two inches into the soil near cut or damaged plants.
To monitor fields, producers should inspect 20 consecutive plants at five different locations, checking a total of 100 plants. While scouting, they should look for cut stems, leaf feeding, and damaged seedlings. Digging near injured plants can help confirm whether cutworms are present.
If 20% or more of the inspected plants are cut and the caterpillars measure less than three-fourths of an inch long, insecticide treatment should be considered. Smaller caterpillars will continue feeding and may reduce plant stands further. Farmers should also consult the latest South Dakota Pest Management Guides to select approved insecticides and follow label directions. Regular scouting and timely management remain the best ways to reduce crop losses from dingy cutworms.
Photo Credit: pexels-hong-kimvai
Categories: South Dakota, Crops, Corn, Soybeans, Wheat