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What Kevin Bradley is watching for in 2022

Missouri’s Weed Management Specialist warns about herbicide shortages, weed resistance.

Seemingly every day, Kevin Bradley receives an email about how global supply chain issues are wreaking havoc on the availability of herbicides for the 2022 crop season. Glyphosate and glufosinate – the active ingredients in Roundup and Liberty, respectively – are most at risk for short supply.

“But there’s talk of 2,4-D too,” says Bradley, who is the weed management specialist at the University of Missouri. He spoke to growers at the annual Missouri Crop Management Conference in late November.

What to do about the potential for herbicide shortages is not rocket science, he adds. Obviously, the sooner growers can take possession of the products they need, the better off they will be.

Kevin Bradley, University of Missouri weed specialist
Kevin Bradley
“But this year, more than ever, we need to be better stewards of our chemicals,” Bradley emphasizes. Farmers cannot afford to apply incorrect rates, or try to treat weeds that are too big. Correct nozzle packages are imperative, as are using adjuvants when called for. In short, “we need to optimize everything we can to do it right,” Bradley says. “We can’t be spraying these big weeds and having to go back and respray in 2022.”

For corn, weed control remains pretty simple, even without glyphosate and glufosinate. There are plenty of herbicide options that don’t include those two active ingredients.

“This is the year you need to get on board with pre- and postemergence residual herbicides as much as possible. We still have plenty of options in corn that don’t include glyphosate or glufosinate,” he says.

Group 4 products are available, often in mixes. And Group 27 products, like mesotrione, are commonly available active ingredients. Group 2 ALS Inhibitors, and atrazine, are also in ample supply.

Soybeans: a more difficult task

Soybeans without glufosinate or glyphosate? It’s more difficult than corn, but possible. Just heed Bradley’s advice: “We have to optimize our effective pre- and postemerge residuals as much as possible.”

Four years of data from Bradley’s department shows that soybean fields containing both a pre- and postresidual herbicide provide 91% control of waterhemp (vs. 87% for preresidual and a postapplication that doesn’t contain residual activity) and 94% control of grassy weeds (vs. 88% for preresidual and a postapplication that doesn’t have residual activity).

“However, there was no difference between the two programs for broadleaf weed activity,” Bradley notes. “So know what you’re going after. Residual herbicides are not really designed for things like cocklebur, ragweed, and morning glory. But they are going to do great things for waterhemp, palmer amaranth, and grasses.”

Bradley says that to maximize glufosinate and glyphosate, you must use them in a timely fashion.

“We cannot stand to have you making these applications on larger weeds,” he says. “This happens every year usually because we get behind and a co-op has thousands of acres to spray with a limited time to do it.”

Spraying smaller weeds with a reduced labeled rate of herbicide should provide effective control. The key is to get out in the field, scout early and often, and target smaller weeds.

Here are other strategies the weed scientist offers for 2021:

  • Time to till? While Bradley isn’t necessarily a proponent of tillage, he suggests that 2022 may be a year to break out tillage equipment. “If you’re not against tilling this may be a year to think about it, probably more so than in some other years,” he says.  “If we’ve only got a certain amount of product to deal with, and if we’ve got one way to eliminate a burndown, maybe this is a way you can use the amount of herbicide you have the best you can.”
  • Think differently on cover crops. For farmers who have grass cover crops growing over the winter, the conventional wisdom is to spray these covers early, which will require a smaller dosage of glyphosate than if sprayed later. “I’m not sure I agree with that,” Bradley says. While spraying early is an option, Bradley says many farmers who delay spraying grass cover crops until after cash crops are planted in the spring – or “planting green” – like the weed suppression that a mat of cover crops provides. Farmers can plant the cash crop into standing covers, then spray with glyphosate and another contact herbicide like Sharpen and apply a residual herbicide thereafter.
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