Cotton Links


Reaping Rewards With Residuals

Residual herbicide applications at layby mean added crop protection for cotton producers, and they are encouraged to use residuals in their Roundup Ready cotton programs this season.

“I think the value of a residual is starting to be seen,” says Darrin Dodds, Mississippi Extension cotton specialist. “From my standpoint, I encourage the use of a residual whenever we can get it in, especially in light of resistance problems.”

Resistant pigweed is a major concern for Dodds and other Mid-South Extension agents and a reason he recommends residual herbicides.

“The pigweed threat scares us a lot,” he says. “I have seen data from Georgia where they put 264 ounces of glyphosate over the top of their cotton, and there are still pigweeds coming through it.”

Arkansas producer Allen Donner started using Valor herbicide at layby to gain better control of pigweeds on his farm.

“We’ve been using Valor in the summer application for three or four years now in a layby program,” he says. “We have a tremendous problem with pigweed, and it has helped us out immensely. We previously used diuron products, which you could mix with Roundup and get probably 70 percent control, but with Valor we pretty much get a good 95 percent control.”

Parrlay, Staple, Cotoran and Caporal are also good tankmix options for layby applications in Roundup Ready cotton programs. Adding one of these residual herbicides into the mix at layby can help farmers preserve the available technology.

“We have what we have as far as herbicides, since not a whole lot of new herbicides are being introduced these days,” Dodds says. “So, we really have to protect what is currently available. One of the best ways to do this is to stop relying on one herbicide for weed control across the board.”

Layby Practicalities

Incorporating a residual at layby is a practical step for cotton farmers, even if they are not concerned with resistant weeds or chemical rotation.

“Anytime you talk to a farmer and he doesn’t have a residual in the tank at layby, he typically will get grasses and small-seeded broadleaf weeds later in the season,” Dodds says.

These grasses and weeds germinate as a result of rainfall or irrigation.

Larger grasses and broadleaf weeds later in the season, and even after harvest, can continue to spread seeds into the soil seed bank which can cause more grass and weed problems in the future. Also, if the grasses and broadleaf weeds are large enough they can hinder harvest equipment.

According to Dodds, once the window for layby applications passes, there are few things farmers can do to control weeds and grasses.

The Education Curve

For those farmers who have not had firsthand experiences with resistant or problematic weeds, he emphasizes how a residual can help fend off potential weed problems.

Dodds tries to educate as much as he can and often points to examples from surrounding states that have problems, such as pigweed, and encourages farmers to be proactive and use a residual to hold the weeds back and keep the fields clean.

“I encourage the use of a residual because of the current problems we have and some of those looming on the horizon,” Dodds says. “A residual herbicide is a good insurance plan.”

Archer-Malmo, which represents Valent, provided information for this article.


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