Black cutworm.
Black cutworm.

Large populations of black cutworms reported last week in Indiana and Kentucky means Ohio farmers can soon expect to see the migratory moths in the Buckeye State, an entomologist with the College of Food, Agricultural, and Environmental Sciences at The Ohio State University said.

Black cutworms have been reported in the neighboring states of Indiana and Kentucky in significant numbers in traps set up by entomologists to determine the number of moths migrating up from the South, said Andy Michel, an Ohio State University Extension pest expert. Large numbers of armyworms have also been caught in the Kentucky traps, Michel said.

Since these are migratory pests, Ohio growers should be prepared to start scouting their fields once corn is emerging or has come up. Both insects can cause significant stand loss in corn, he said. Armyworms can also be a significant pest of wheat.  

While not a widespread problem throughout Ohio, black cutworms tend to infest fields with significant ground cover and weed presence, said Michel, who also has an appointment with the Ohio Agricultural Research and Development Center. Black cutworms are especially attracted to chickweed, he said.

OSU Extension and OARDC are the statewide outreach and research arms, respectively, of the college.

“With black cutworm, growers can find significant injury especially after planting, right when the corn is starting to emerge,” he said. “This year, emergence is likely to occur during the first or second week of May if growers are able to start planting soon.

“Females like to lay eggs in fields with heavy weed cover, and as these weeds are killed by tillage or herbicide, the larvae move on to feed on emerging corn. Black cutworm can cause severe cutting of the plant. The resulting stand loss in corn is generally associated with below- or at-ground-level feeding injury, which occurs below the growing point.”

Growers who have fields with a history of black cutworms are more likely to have cutworms in their fields, Michel said.

“There are certain transgenic varieties of corn, including those with the Viptera trait and Cry1F trait, that will do a good job of protecting against black cutworm,” he said, noting that this week Kentucky officials reported seeing black cutworms at “a concerning level.”

Female armyworms lay eggs in grasses including wheat, where eggs hatch over two weeks, Michel said. As the larvae grow, they can defoliate wheat plants and lead to yield loss. Armyworms can also cause damage to corn that is planted into wheat fields or other fields that have a grassy cover, he said.

“If you do have an infestation, you could have some significant stand loss, with areas that may need replanting or rescue treatments,” Michel said. “Growers who find black cutworm infestations may find that rescue treatments are more effective than preventive treatment, including insecticidal seed treatment.”