Cut Down on Weed Escapes

Like clockwork, Mid-South cotton growers know that pigweed escapes will begin to pop up in their fields by mid-July.

In addition to being prolific seed producers, the pesky weed can also feature resistance to several types of herbicides, making escapes all the more likely throughout the summer months.

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“Everybody and their brother knows that we’ve got glyphosate resistance,” says Darrin Dodds, Extension cotton specialist with Mississippi State University. “I think everybody realizes there is a large amount of ALS resistance in those populations as well. The thing we’ve cautioned people about this year, is to not get caught behind the eight-ball, because this PPO resistance in Palmer amaranth is spreading.”

Dodds says keeping a vigilant eye on the fields is important as the summer drags on.

“Most folks are watching close enough so that they’re not going to get caught in that situation,” he says. “But especially come July, if you have put down Reflex and think you’re going to get good activity out of it because you always have, then, all of a sudden, you may have a pigweed population blow up on you that you weren’t really expecting. I would encourage folks to really be aware of where those populations are at and do everything they can to get those populations under control.”

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Because of the label restrictions on most herbicides, cold steel may be the best and only option for weed control in the late summer months. Taking the time to chop escapes and remove them from the field as early as possible pays huge dividends down the road. And as Dodds notes, a single pigweed is still very competitive in a cotton field.

“There’s research that shows a single pigweed plant in 30 feet of row can cost you 15% yield of cotton,” he says.

But as Extension experts in the Mid-South have stressed, winning the numbers battle against seed populations is the bigger goal when it comes to removing pigweed escapes.

“Say you’ve got 20 or 30 escapes in an acre,” Dodds says. “If those are female plants, and are very healthy and robust, they could make 500,000 seeds per plant. If you let 20 of those go, you’ve left 10 million seeds going into the soil. To me, I’d be willing to chop and remove those plants from my field just to eliminate problems down the road.”

Removing the chopped weed from the field is an important step in reducing the seed population in a given field. While it may not be feasible in some scenarios, ideally the chopped plant can be loaded onto a trailer and driven away in order to reduce the number of seeds that may fall off the plant and into the field during removal.

“Even if you drag them out on the ground, you’re probably going to lose some seed, but the overriding point is that you’re not going to lose the 500,000 seeds that are growing on that plant,” Dodds says. “Unless it’s in a very mature state where when you touch it, the seed head almost shatters like a soybean does, you’re still going to get the vast majority of the seeds out of that field.

“With pigweed, it’s always a numbers game,” Dodds says. “Anything you can do to reduce the number of seeds in the soil and subsequent plants that come up and cause you problems, the easier it’s going to be to get them under control.”

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