Warm Winter Could Bring Early Insects

While the near-record warm winter will cause some insects to appear earlier than normal, whether the bugs negatively impact field crops will depend on spring weather, insect variety and planting dates, says an Ohio State University Extension entomologist.

Insects such as the bean leaf beetle, corn flea beetle and alfalfa weevil 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.

This winter 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 when 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.

The warmer weather will cause insects to come out earlier to feed and become more active in the months before spring, Hammond said.

In addition, many insects migrate from southern areas, such as black cutworm, true armyworm and potato leafhopper, he said, noting that their development is affected by weather conditions farther south. Whether they migrate into the Eastern Corn Belt earlier will depend on the weather conditions later this spring, he said.

The impact these bugs can have on field crops depends more on the stage of crop development and growth, Hammond said.

“If insects arrive in fields early but no crop is even planted, this could lead to greater mortality if they cannot find alternative hosts,” he said.”However, if the insect arrives or begins feeding earlier when crops are smaller in size, a greater potential for injury exists.”

However, corn flea beetles in particular, and their ability to vector Stewart’s bacterial wilt, is of concern this year because of the warmer winter temperatures, Hammond said. In fact, more corn flea beetles are expected this year, significantly increasing the potential for Stewart’s bacterial wilt.

Farmers can mitigate the damage if they scout their fields earlier and with more tenacity, he said.

“We recommend that growers scout, scout, scout,” Hammond said. “Growers need to be out in their fields to be aware of the insects they’re dealing with and pay more attention this year, especially in the crop rows, because more insects may be waiting for crops to come out of the ground.”

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