WOOSTER, Ohio — According to the National Oceanic and Atmospheric Administration, the winter of 2012 is the warmest nationwide since 2000 and the fourth-warmest winter on record.

The unseasonably high temperatures were a result of the jet stream, which divides the cold air to the north from the warm air to the south, settling at a much higher latitude. All this has been good news for farmers looking for a head start on the 2012 crop season.

But the lack of a deep freeze across the Midwest gave insects, weeds and crop diseases a jump on the season as well.

“The warm winter will bring these pests to the forefront, and we know they’ll be arriving earlier, but we must wait and see if they’re more in abundant or not,” said Ron Hammond, Ohio State University extension field entomologist at the Ohio Agricultural Research and Development Center in Wooster.

“My best estimation is they’ll all be arriving in the fields earlier, and I’m almost certain these pests will be larger than normal.”

According to Hammond, there are two ways insects can arrive: they can overwinter in the field, or they can migrate from somewhere else. Knowing which insects overwinter in an area tells growers what to watch.

In Ohio, they’re tracking corn flea beetle and alfalfa weevil populations this spring. Corn flea beetles are particularly worrisome because they cause physical damage to seedlings and are a vector for Stewart’s wilt.

Migratory insects should be managed on a case-by-case basis. Black cutworms, for example, fly north to the Midwest and are attracted to chickweed, which thrives in mild winters.

“What I’ve been recommending is what we say every year – scout, scout, scout,” Hammond said, adding that some farmers might not have to chance a thing while others may have to be more careful this year.

“The area where warmer temperatures can, and probably will, impact field crop insects concerns when the pests might show up and require scouting,” he said. “The first good example is with alfalfa weevil on alfalfa. The time for scouting for the alfalfa weevil will come earlier in the season. As usual, I recommend sampling to determine the actual need for treatment.

“There are many insects that migrate from southern areas, so their development is affected by weather conditions further south. Some of these pests include black cutworm, true armyworm and the potato leaf hopper. Whether they migrate earlier or not into Ohio will depend on the weather conditions later this spring.”

Some of the invasive and damaging pests growers can expect to see more of this year (with expert analysis) 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 already are being collected throughout the Midwest.

So, 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. If only a few fields have emerged crops, however, 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 will 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 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.