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The threat of Black Cutworm in the Midwest

Black cutworm damage can be underground when it's dry.

June 12, 2023

2 Min Read
Scouting for cutting damage and digging fields is the best way to identify a potential issue. Corteva Agriscience

Black cutworm (BCW) is an aggressive pest that arrives in the Corn Belt in late spring, feasting on many plants, including corn, cotton, tobacco and turf grasses. While BCW overwinters throughout the southeast United States, it moves prominently north with spring storms.

“It’s black cutworm that we worry about,” said Matt Montgomery, Pioneer Field Agronomist in Illinois.

Black cutworms can be identified by their body segments. A gray body with four dots – two small and two large – distinguishes BCW from other common cutworms, such as armyworm.

When smaller, BCW larvae will chew holes in the leaves. When grown, adult BCWs begin cutting V1 to V5 plants and even drill into V6 to V8 plants, killing the growing point. In wet soils, cutting will occur mostly above ground. With dry soil, a majority of cutting will be below ground.

Economic thresholds for black cutworm are 2, 3, 5, and 7 cut plants per 100 plants for seedling, V2, V3, and V4 stage plants, respectively.

Scouting for cutting damage and digging fields is the best way to identify a potential issue. Applying a rescue treatment is the most effective and economical way to control black cutworm populations once identified. Broadcast pesticide or bait application may be used as a rescue treatment in cases of higher pest pressure and crop damage.

Utilizing products with traits that provide cutworm protection are the best way to proactively deal with BCW. Insecticide seed treatments at high rates may give some control, but lower rates are not as effective.

If fields have a history of BCW pressure, they are more likely to have repeat instances. In these cases, growers should monitor moth flight reports, consider reducing tillage and/or eliminate other practices that leave a food source for the young larvae.

“If you’re seeing heavy cutworm pressure, you need to strongly consider fall weed control,” Montgomery said. “Farmers have less and less time in the spring to clean up fields and spray for pests. It’s absolutely critical to start clean and stay clean.”

Source: Corteva Agriscience

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