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All Traits Still Controlling Pests in Indiana

All Traits Still Controlling Pests in Indiana
Rootworm control failure as close as east-central Illinois.

Two years ago the failure of Bt corn rootworm, a specific event, in western Corn Belt areas, including parts of Iowa and Minnesota, made news. There may still be debate over whether it was true resistance, but many agronomists and entomologists pointed to characteristics of the outbreak that usually signify resistance.

Remember the refuge: Note the small amount of seeds of different color in this seed corn bag. That is a hybrid without a Bt trait, providing refuge in the field without planting separate strips.

This season two counties in Illinois were host to control issues with the same trait. University of Illinois specialists confirmed there were control problems. However, the lack of control has not yet occurred in Indiana. That's good news, although the close proximity of control problems concerns agronomists. They believe it's time to be vigilant, make sure you're using refuge and think through rootworm control strategies again.

The fields in east-central Illinois were planted with a traited hybrid that contained a single rootworm protein, Cry3Bb1. It's the same protein that has been under duress in the western Corn Belt.

Jeff Nagel, Lafayette, an agronomist with Ceres Solutions, is suggesting that farmers follow a series of guidelines to manage rootworm in Indiana. He is concerned by the appearance in Illinois, but notes that so far, the fact is that it has not been observed in Indiana.

"Use crop rotation when possible," he says. The problem first showed up in western states in fields which had been in continuous corn for several years.

"Control volunteer corn in soybeans, especially if the previous crop contained a rootworm-protecting trait," Nagel continues. "Always plant the required refuge if you're not using refuge-in-a-bag."

In refuge in a bag, a second hybrid is included at low percentages which does not contain the rootworm trait. The strategy is designed to limit development of resistant insects.

"Consider planting pyramided hybrids that contain two proteins that are effective for rootworm control, particularly in corn on corn rotations," says Nagel, who is also an Indiana certified crop adviser.

As for soil insecticides, Nagel recommends them if you're in continuous corn and planting a hybrid that only has a single trait for rootworm control.

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