Few Insect Problems Impacting Crops So Far

There are potential pests to watch for, however.

Published on: Jun 30, 2008

John Obermeyer and Christian Krupke must feel like the Maytag repairmen in the commercials of old. These two Purdue University entomologists haven't had any major insect outbreaks to chase down yet this season.

"My phone certainly isn't ringing off the wall," Obermeyer told farmers at a recent field day. "It's not ringing much at all. That tells me there aren't many insect problems showing up in the country so far."

That may be little solace for farmers with flooded out and stunted crops to wake up and see every morning. And even though there are few insect problems right now, Obermeyer cautions that careful scouting is still a good idea. Insect problems could arise later.

Rootworm dig season is virtually upon us. While the specialist hasn't heard of problems yet, that means there won't be later on. And he reminds farmers that unlike Bt cornborer, which expresses itself throughout the plant and virtually can wipe out corn borers, the rootworm Bt trait only expresses itself in the roots. It also delivers 75 to 80% control, not 100%, in most cases. So finding a few rootworm larvae even in Bt rootworm fields shouldn't be a surprise.

The insects Obermeyer has talked about most so far this season are ones that don't even show up on radar in some years, at least not this early. Armyworm has been reported in fields from North Vernon to Greensburg. Spraying has been necessary in some fields. Generally it's in fields where there was a cover crop or other green cover until late spring.

Then, Obermeyer has found corn earworm larvae in sweet corn, about two months earlier than normal. While it's far from an epidemic, he advises sweet corn growers to check their fields soon, and often. Earworms go through a rapid life cycle, and larvae can appear very quickly.

These two insects likely showed up early because they rode the storm fronts that produced June flooding northward from the Gulf. Normally those weather patterns don't develop until sometime in August, meaning the insects can't hitch a ride until much later.

What does corn earworm mean for field corn later in the season? Maybe nothing, but Obermeyer is honest when he answers the question. "We really don't know," he says. "We've never seen it come into the state as early as it did this year."

One other pest worth watching will be soybean aphid in northern Indiana, probably mostly on very-ate-planted soybeans, later in the season, he adds. And Obermeyer cautions that while it's a slow year for insects so far, there's no guarantee that it will remain quiet.