Manage your way out of corn rootworm

DUBUQUE, Iowa — AgriGold agronomist Ron Roling knows a thing or two about corn rootworm.

He’s from eastern Iowa, the self-proclaimed corn rootworm capital of the world.

As an agronomist there, Roling knows how to protect corn yields from the pests. And it takes a combination of several tactics.

“There’s no rescue treatment,” Roling said. “But farmers can eliminate corn rootworm with a six- to 10-year plan of attack using a combination of management tactics.”

That plan should include rotating products that include protections that defend against corn rootworm, incorporating a soil-applied insecticide, beetle bombing and rotating to soybeans for at least a year.

Roling encourages farmers to monitor later-planted and replanted cornfields closely, especially if surrounding fields were planted in a timely manner.

“Corn rootworm beetles are attracted to fields with the greenest vegetation and best food sources,” he said. “Look for silk clipping in those fields and consider crop rotation next year.”

Corn hybrid selection and crop rotation are both important.

“One of the strengths of AgriGold’s lineup is multiple above-ground and below-ground traits on our hybrids,” Roling said. “We’re able to use multiple traits and insecticides over that six- to 10-year plan period. That’s critical for corn rootworm resistance management.”

“At least one of those plan years should be a year of soybeans. Planting soybeans for a year can knock corn rootworm population down to zero and keep it there with the corn rootworm management system.”

During that year of soybeans, Roling said, it’s critical that farmers manage weeds and volunteer corn, which are hosts for corn rootworm.

In addition to soil-applied insecticide, farmers in high-pressure areas should also consider a well-timed beetle bomb.

While farmers would prefer to spray their foliar insecticide when they’re doing a fungicide application, that’s not always the best timing. Male beetles emerge around that time, but female beetles emerge several weeks later.

Doing your beetle bomb at the same time as your fungicide might be convenient, but it isn’t the most effective timing, Roling said.

“Farmers have better results doing their beetle bomb a few weeks later when egg-laying females emerge,” he said.

A long-term, systems-based approach can rid fields of corn rootworm, Roling said.