Field Crops July Newsletter

By Lilly Bunch

Corn earworm activity has been reported in soybean fields across northeastern North Carolina, including Pasquotank County. These reports are much earlier than we typically expect, as corn earworms usually become a concern later in July. Dr. Dominic Reisig, NC State Extension Specialist, recently published an article on corn earworms in flowering soybeans. These are the highlights:

1. Early corn earworms don't always mean it's time to spray. Corn earworms are showing up earlier than usual this season, likely due to moths migrating from the south. While this can lead to higher populations in early-planted soybeans, soybeans at the R1-R2 (flowering) stages can usually tolerate flower feeding without yield loss—especially if the crop is not under stress.
2. Scout carefully once pods begin to develop. The risk of yield loss increases when soybeans reach the R3 (beginning pod) stage because earworms begin feeding on pods rather than flowers. Continue scouting fields and monitor the NC State light trap network, as corn earworm pressure is expected to increase later in the season as moths emerge from corn fields. You can utilize the NC State Extension Corn Earworm Economic Threshold Calculator.
3. Choose insecticides wisely. If treatment is needed, use products that effectively target corn earworm while preserving beneficial insects. Avoid broad-spectrum insecticides like acephate and pyrethroids unless another pest requires them, as they can flare secondary pests such as soybean loopers and spider mites.