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Early corn planting could up pest dangers

If you're planting corn this early, how will your crop's insect pressures differ from a more "normal" year?

Farmers taking advantage of the quick start to spring could face different pest pressures at earlier- and later-than-normal times, meaning protection and control methods will likely change.

"The mild winter will very likely improve the survival of some insect species, such as corn flea beetles, bean leaf beetles, soybean aphids and white grubs that overwinter in Illinois," says University of Illinois Extension crop scientist Mike Gray. "For other insect species, such as European corn borers and western corn rootworms, are superbly adapted to survive even the most severe winters, especially if snow cover is present."

Beefing up protection

Now, tack on the quick spring and it's a recipe for potentially fast, more severe early bug pressures from black cutworms, for example. Then, add in winter annual weeds, more host plants, that are also expected to develop quicker than normal and it all equals more potential pressure.

So, the equation adds up to an awfully favorable outlook for pests like the black cutworm and western corn rootworm. If you think that just because you plant a Bt corn variety, you'll be able to avoid problems with the latter bug, you may be surprised.

"Obviously, a lot of growers will utilize Bt hybrids for rootworm. This year, the hatch may be earlier, around the middle of May. Let's say you have larval feeding that extends well into July," Gray says. "Will you have hybrids still expressing their Bt rootworm genes at optimal levels for that feeding period?"

If you're already planning on adding to your Bt protection by putting down a soil insecticide, Gray says you still may have the same problem. "The question being raised is, if it's applied so early in the season, will it get you through the rootworm feeding season as late as early August?" he says. "That's 4 months that we're asking that insecticide to work."

Other pests

At least in the central Corn Belt, white grubs and wireworms could flare up because of the early start to spring, Gray says. White grubs typically pupate when corn's usually being planted later in the spring. This year, though, that will happen when the crop's further along, meaning they'll have more plant material on which to feed. If the unseasonably warm weather holds, the same could be true for wireworms.

"When the soil temperature starts to warm up in the spring, wireworms tend to move further down in the soil. If we were to return to a cool, wet pattern, we could expose developing seedlings to a longer feeding period for wireworms as well as white grubs."

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