New Day for Controlling Volunteer Corn

Glyphosate-resistance makes it a different ballgame.

Glenn Nice fielded questions last spring that wouldn't have cropped up some 5 to 10 years ago. After the nasty weather spell of May 7-9 stayed around and wore out its welcome, many farmers were faced with replanting corn. But some of that corn was Roundup Ready, resistant to glyphosate. Tilling would knock it down. But no-tillers faced a different challenge with replanting.

"If you're faced with that situation in corn, you've got Gramoxone Inteon before you replant, or you've got Liberty," Nice says. "Liberty will take down glyphosate-resistant corn. But you may want to consider replanting with Liberty Link corn if you take that option." Check the labels of these or any products, and consult with company reps before deciding to go with one of these options, Nice cautions. Plantback restrictions can become an issue in certain situations.

Several companies are looking into labels that would shorten plantback restrictions so their product could be used for this purpose, perhaps through emergency labels, he notes. It's more of a niche market and doesn't offer high enough profit potential for companies to invest millions in labeling a product just for this purpose.

Many folks last season disked up failed stands to replant. Others chose to plant into existing stands. Those following the latter method sometimes wound up with super-thick corn, as more of the first planting than anticipated finally emerged.

Meanwhile, taking out volunteer glyhosate-resistant corn in soybeans is an easier challenge, the Purdue University weed control specialist says. Select or Select Max are available. The same chemistry may also be offered in generic form.

Also beginning this year, Assure II is now an option for taking out resistant volunteer corn.

The whole topic is a case of unintended consequences. Fortunately, there are still enough tools around to allow farmers to resolve the issue, and continue using glyphosate-resistant corn where they choose.

About 50% of the corn grown this year is expected to be glyphosate-resistant, Nice says. That compares to about 90-91% of the soybeans being Roundup Ready.

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