What To Expect After A Mild Winter

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Coming off an unusually warm winter, what should vegetable growers be wary of in the coming months? What impact will these mild temperatures have on insect pest pressure?

Brian Nault, an associate professor in the Department of Entomology at Cornell University, says mild winters with little snow fall often permit greater survival of insects that overwinter in the soil or in leaf litter in northern climates, like New York.

“Often, limited snow cover means that the ground where some pests overwinter is not well insulated and this would increase mortality if temperatures are extremely low for several days (zero or low teens for an extended period),” says Nault. “However, this winter, temperatures were mild enough that the insulation provided by snow was never needed.”

If the weather continues to be warmer than normal, insect pests will emerge earlier than usual, he continues.

“If growers plant crops earlier than usual, the pests will be in sync with the crops and everything will seem ‘normal’,” Nault explains. “If pests emerge earlier and growers hold off and plant at typical times, several scenarios could unfold. In some cases, the pest may attack the crop when the crop is younger and more vulnerable to damage (e.g., Colorado potato beetle). In other cases, the pest may emerge to find that it has no food because the crop has not been planted.”

Nault adds that the warm temperatures could present bigger problems with pests having multiple generations per year. He cites thrips and aphids as an example. “Extra generations could be completed because the season will be extended for them.”

Mike Orzolek, professor of vegetable crops at Penn State University, says that in addition to possibly dealing with insects earlier in the season, growers may be faced with earlier weed seed germination and possibly higher weed populations.  

“Scouting for pests as soon as a crop is either seeded or transplanted will be critical this year to obtain maximum crop yield,” adds Orzolek.  


Rosemary Gordon is editor of American Vegetable Grower, a Meister Media Worldwide publication.

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