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Plan Your Rootworm Strategy To Keep Resistance Away

Several steps will help you do your part to keep resistance issues out of Indiana

Tom Bechman 1

January 30, 2014

2 Min Read

Just a few years ago word broke that corn rootworms were breaking through GMO-resistance in a few fields in Iowa and Minnesota. The fields had one thing in common- most, at least at first, had been in continuous corn for several years, and the same rootworm trait had been used year after year.

Last year word of an outbreak in a county in central to east-central Illinois captured the headlines. So far no corn rootworm resistance has been documented in Indiana. The only trait that has not controlled corn rootworm effectively in these other areas of the Corn Belt is Monsanto's cry3Bb1 trait.


Steve Gauck, an agronomist for Beck's Hybrids, based in southeast Indiana, says the goal is to keep Indiana free of corn rootworm resistance issues. He offers several steps that should help prevent corn rootworm resistance from showing up here.

"The first step is to rotate crops," he says. "There is an advantage to a corn and soybean rotation.

"Second, you need to control volunteer corn in soybeans, especially if it was GMO corn with the rootworm trait. The volunteer corn may have some level of the protein, but not enough to kill off larvae. Some might survive."

Third, consider selecting hybrids that stack rootworm events in the hybrid. In other words, there is more than one mode of action to kill rootworms. When there is more than one mode of action it is more difficult for rootworms to develop resistance. You can also select hybrids that have rootworm traits pyramided on top of each other, he says. This means there are at least three traits in the hybrid that can control corn rootworm larvae.

Finally, it's important to practice refuge requirements. While there is no documentation many believe that many farmers were lax on this requirement when they were supposed to leave strips of non-GMO corn for refuge.

The new hybrids are typically refuge-in-a-bag, either at 90-10 or 95-5%. Hybrids with three rootworm traits will definitely be 95-5, meaning 95% of the seed is GMO and only 5% is a non-GMO hybrid susceptible to the rootworm.

About the Author(s)

Tom Bechman 1

Editor, Indiana Prairie Farm

Tom Bechman is an important cog in the Farm Progress machinery. In addition to serving as editor of Indiana Prairie Farmer, Tom is nationally known for his coverage of Midwest agronomy, conservation, no-till farming, farm management, farm safety, high-tech farming and personal property tax relief. His byline appears monthly in many of the 18 state and regional farm magazines published by Farm Progress.

"I consider it my responsibility and opportunity as a farm magazine editor to supply useful information that will help today's farm families survive and thrive," the veteran editor says.

Tom graduated from Whiteland (Ind.) High School, earned his B.S. in animal science and agricultural education from Purdue University in 1975 and an M.S. in dairy nutrition two years later. He first joined the magazine as a field editor in 1981 after four years as a vocational agriculture teacher.

Tom enjoys interacting with farm families, university specialists and industry leaders, gathering and sifting through loads of information available in agriculture today. "Whenever I find a new idea or a new thought that could either improve someone's life or their income, I consider it a personal challenge to discover how to present it in the most useful form, " he says.

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