Warm winter increases field crop insect and pest threat in Ohio

COLUMBUS — Crop growers should take extra precaution to scout their fields this spring for black cutworm, slugs, bean leaf beetles, rootworms and other invasive insects.

The near-record warm winter Ohio has experienced this year is expected to cause a significant increase in the potential for crop-damaging pests, according to Ohio State University Extension entomologist Ron Hammond.

The bad guys

Insects such as the corn flea beetle, which targets corn through the spread of the bacterium that causes Stewart’s bacterial wilt and leaf blight on both field and sweet corn, likely will be seen earlier than normal this year. Black cutworms also could be a bigger problem this year, as could slugs, bean leaf beetles and cereal leaf beetles, he said.

— Black cutworm: Weed growth has been heavier this year because of the earlier warm weather, especially chickweed. With this extra growth comes the potential for greater black cutworm problems, as adult cutworms already are being collected throughout the Midwest.

When corn is planted and starts to emerge, cutworms already might be at damaging stages. Thus, there is a greater need to pay extra attention in those fields conducive to cutworm problems, such as no-till and/or weedy fields.

— Slugs: Warmer weather and soil temperatures will cause slugs to hatch and begin heavier feeding earlier. If planting times are normal, slugs will be a bigger and larger threat than normal. If planting early, slug feeding could be more similar to normal conditions. If planting late, slugs will be relatively larger and capable of even heavier feeding.

— Bean leaf beetles: Growers may find more bean leaf beetles this spring. But, if most fields are planted and crops emerged about the same time, the beetles should disperse themselves over all those fields and not be a major problem.

However, if only a few fields have emerged crops, beetles could concentrate on those fields and require growers to monitor them more closely.

— Rootworms: While rootworm larvae are expected to hatch earlier this year, they won’t necessarily cause more problems. Because most fields already are planted to transgenic varieties with rootworm control, treated with a soil insecticide if continuous corn or are part of a rotation, good control is expected.

Growers likely will not need to make any additional or two-tactic applications, such as soil insecticide applications on transgenic corn.

— Corn flea beetle: Seed treatments on most corn should offer control, at least for the beetle, but it is not clear how it would affect Stewart’s wilt.

Growers should scout any non-seed treated fields, along with popcorn and sweet corn fields that usually are more susceptible to Stewart’s wilt, along with any field corn hybrids that are more susceptible.

— Cereal leaf beetle: Growers can expect the earlier presence of cereal leaf beetle larvae, and should scout wheat and oats earlier. The potential for beetle survival is greater this spring.

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