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College of Food, Agricultural, and Environmental Sciences


Near-record Warm Winter Increases Insect and Pest Threat for Crop Growers This Spring

April 13, 2012

WOOSTER, Ohio – Crop growers should take extra precaution to scout their fields this spring for black cutworm, slugs, bean leaf beetles, rootworms and other invasive insects as the near-record warm winter Ohio has experienced this year is expected to cause a significant increase in the potential for crop-damaging pests, an Ohio State University Extension entomologist said. 

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, will likely be seen earlier than normal this year, said Ron Hammond, who also has an appointment with the Ohio Agricultural Research and Development Center.

Black cutworms could also be a bigger problem this year, as could slugs, bean leaf beetles and cereal leaf beetles, he said.

Winter 2012 is the warmest winter experienced nationwide since 2000 and the fourth-warmest winter on record, according to the National Oceanic and Atmospheric Administration. This was caused because the jet stream, which divides the cold air to the north from the warm air to the south, settled at a much higher latitude this year, the federal agency said. 

Some of the invasive and damaging pests for which growers can expect an increase this year include:

  • 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 are already being collected throughout the Midwest. So, when corn is planted and starts to emerge, cutworms might already 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 earlier and will result in slugs beginning their heavier feeding earlier. If planting times are normal, slugs will be a bigger and larger threat than normal. If planting early, perhaps the slug feeding will be more similar to normal conditions.  If planting is late, slugs will be relatively larger and capable of even heavier feeding. 
  • Bean leaf beetles: Growers may find more bean leaf beetles this spring because of the warm winter. But, if most fields are planted and 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, those fields will still get them all and potentially be problem fields that would need extra monitoring.
  •  Rootworms: While rootworm larvae are expected to hatch earlier this year, they are not expected to necessarily cause more or greater problems. Because most fields are already transgenic for rootworm control, treated with a soil insecticide if continuous corn, or are part of a rotation, there is an expectation of good control. Growers likely will not need to make any additional or two-tactic applications, such as making soil insecticides 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 what the impact would be on Stewart's wilt. Growers should plan on scouting any non-seed treated fields along with popcorn and sweet corn fields that are usually more susceptible to Stewart's wilt, and any field corn hybrids that are more susceptible. 
  •  Cereal leaf beetle: Growers can expect the earlier presence of cereal leaf beetle larvae, and need to scout wheat and oats earlier.  Because of the potential for greater survival, doing so is more important this spring.  


Tracy Turner
Ron Hammond