When it comes to the damaging potential of cutworms in corn — even in Bt varieties, size matters, said Van Banks, Monroe County Extension agent for the University of Arkansas Division of Agriculture.
“It’s important to keep in mind that even if the variety is rated good for cutworm resistance, it’s the size of the larvae feeding on the corn that matters. Damage can occur if the cutworks grow large from feeding on weeds, then move over to corn.
“That’s why it’s important to keep a clean seedbed for a couple of weeks before planting, even in Bt corn.
Because corn planting is less dense than in other crops, losses are felt more keenly, said Banks.
“We encourage producers to scout corn for cutworm damage starting the first week following emergence. Early instars of cutworm feed on leaf tissue and resulting damage may be hard to spot.”
Cutworms can move under the soil surface along the seed furrow to feed.
“These plants may be completely removed or may begin to wilt and die with little sign of injury above ground. It is important to know that cutworm larvae are primarily nocturnal and will hide under debris or in the soil during the day to escape sunlight, so finding larvae in the daytime is rare.”
Cutworms are hairless caterpillars that may be gray with tan markings or be gray to black.
Scott Akin, an Extension entomologist for the UA Division of Agriculture, said: “If cutworms are present and significant stand loss is imminent, an insecticide should be applied as soon as possible.
“Pyrethroid insecticides are effective and economical.”
Seed treatments, such as Poncho, Cruiser, Avicta Complete Corn, etc., have shown little activity against cutworms, Akin said.
For more information on insect control, visit www.uaex.edu, or contact your county Extension office.