Putting a Hood On Resistance
June 22, 2011 Not too long ago, someone suggested that maybe it was time to pull some of the old hooded sprayers out of the weeds around the shop, flush the tanks, replace the hoses and nozzles, then head to the field.
With glyphosate-resistant Palmer amaranth spreading almost uncontrollably, many growers are returning to the widespread use of residuals, but they need something hotter than a cotton plant can survive, or is susceptible to, to clean up resistant Palmer amaranth escapes in the middles. Hooded sprayers provide that.
But in the case or refitting hooded sprayers that have been neglected and exposed to the elements for years, it may be like putting lipstick on a pig.
This year, Willmar Fabrication has introduced a more modern hooded sprayer – the model 915.
“The 915 Hooded Sprayer is the most effective equipment available for controlling resistant weeds that escape a residual herbicide program,” says Steve Claussen, president of Willmar Fabrication. “Cotton farmers across the South helped shape the design of this new spray hood, which allows for application of herbicides in the row middles to control escaped weeds, while very effectively post-directing another herbicide in the row itself. Using the 915 Hooded Sprayer to control weeds will greatly reduce the need for hand-weeding crews.”
Willard Mims will run one of the new hooded sprayers on his farm near Donalsonville, GA, this season.
“Our Palmer amaranth is not that bad, but we do have plenty. We had a lot of weeds that escaped our layby and we had to pull a lot by hand last year,” he says. “The escapes are one of the reasons we’re going to the hooded sprayer. We used Roundup and Valor at layby, and if we keep doing that, we’re going to have weeds resistant to Valor. That’s what we’re trying to prevent – weeds resistant to another herbicide.
“We’ll go through all of our cotton with the hooded sprayer, and I’m hoping only one time,” Mims continues. “Under the hood, we’ll use Gramoxone and diuron. We’ll probably direct spray under the cotton with MSMA and Caparol. I think that’s a pretty good program.”
Mims is also using cultural practices, such as crop rotation, to expose resistant Palmer amaranth to different chemistries and modes of action.
“Rotation has helped us control Palmer amaranth. We have cotton, we have peanuts and we have corn. Our rotation is peanuts, followed by cotton, followed by corn. Some of it is in a four-year rotation, which is two years in cotton. We deep turn the land when we rotate to peanuts,” he says.
“All of our cotton is strip-till. We burndown with Roundup and 2,4-D,” Mims continues. “Last year, we used Prowl, Reflex and diuron right behind the planter – the Reflex is the residual for the Palmer amaranth. After that, we applied Roundup and Staple. At layby, it was Roundup and Valor.”
Because of the potential for PPO resistance to develop, this year Mims plans to move away from Valor, a PPO, and try either of the residual metolachlor products – Warrant and Dual. But that’s not a knock on Valor. “We may have to move away from the Valor in cotton. I want to save the Valor for peanuts,” he explains. “We can’t have PPO resistance in peanuts.”
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