The message is rather simple: start clean, stay clean; use different modes of action; provide overlapping layers of residual herbicides throughout the season; zero tolerance is the goal; you can’t afford to cut back on weed control.
Cotton farmers face an uphill battle this year as they develop weed control programs that take care of what many expect to be a banner year for glyphosate resistant weeds, especially pigweed. Compounding the problem is the depressed cotton market and the need to manage production costs as closely as possible—without sacrificing profit potential. A recent unprecedented gathering of representatives from nine major herbicide manufacturers in West Texas underlines the importance of the issue and the commitment of industry to cooperate to find solutions. Southwest Farm Press editor Ron Smith covered that meeting and developed this three-part series to show some of the options farmers have to manage tough weed issues. It will take a “back to the future approach, says Helena Chemical Company’s Michael Kenty,
Back to the Future weed control Part 3
The drought effect
Monsanto’s John Everitt says herbicide resistance awareness came on slowly in Texas as farmers worked through multiple droughts. “We saw some escapes in 2011,” he says. “We thought it was just dry, and we didn’t get good control. In 2012, we saw more weeds. In 2013 it was dry and we noticed significant infestations and the drought did not help with the resistance problem. Last year, we saw fields with 100 percent infestation.
“If we see escapes, we have to start treating them like resistant weeds. If you tried controls that didn’t work, you may be making the problem worse so do something different. Go back to yellow and white herbicides.”
Resistant weeds will travel by various means. “With winds blowing at 20 to 25 miles per hour, pigweed pollen can travel 1,000 feet,” says Brent Besler, Syngenta. “That’s assuming a three-foot tall plant. Pollen from a six-foot plant may blow for a half-mile.”
Besler recommends cotton farmers diversify, not just crops but chemistry, including different modes of action. “Also consider cultural practices, including tillage. We’re now seeing more farmers going back to conventional tillage in West Texas.
“Don’t cut rates,” he says, a recommendation each speaker emphasized. “Timely application is also critical. Scout and know the fields.”
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The problem can turn ugly, even uglier than West Texas has witnessed yet. “I watched resistance develop in Mississippi,” says Chris Meador, Valent. “It’s not a matter of if resistance will develop but a matter of when. Start clean and stay clean is crucial. Overlap residual products.”
Droplet size for soil-applied chemistry is not important, he says. “But for postemergence treatments, you need a middle-size droplet.”
Applying Valor in the fall also allows producers “to get ahead of weeds like marestail.
“Follow the three Rs,” he says.
- Residual herbicides to control pigweed.
- Resistant weed control.
- Rotation to provide flexibility.”
Farmers took advantage of a question and answer session to ask if switching to conventional varieties makes economic sense this year, with cotton prices down and considering the need to get back to the type weed control they used before herbicide tolerant varieties.
“At 60-cent cotton, you can’t afford to lose any lint,” Helena’s Michael Kenty said. “Let cotton develop a canopy and then it out-competes weeds.”
He also recommends treating each field separately. “Before eliminating anything, identify what’s in the field and don’t use the same program across the board.”
“Think of variety traits as an insurance policy,” Said Russ Perkins, Bayer CropScience. “It may rain and keep you out of the field so you can’t cultivate.”
Kenty also says a program similar to boll weevil eradication might have some merit but would be difficult to administer. “We don’t have just one host crop to consider,” he says. “To be successful, an area-wide program would require cooperation from all the farmers as well as government agencies that manage railroad rights-of-way, highways and other areas where weeds grow.”
Each company rep agreed that resistant weed management will be a difficult but crucial task for West Texas farmers this year. They also encourage producers to examine their overall weed control strategies to identify weak spots, dependence on one herbicide or one mode of action, for instance, and give some thought to which fields are most likely to host the most weeds and which ones showed possibilities for resistant plants last fall.
Identifying weed species was a top priority for most speakers. Rotating mode of action and zero tolerance should play important roles in 2015 weed management efforts.
It’s an industry-wide concern, Kenty says. “All the major companies are engaged. Monsanto is offering a resistance rewards program with cash incentives for using certain products to help manage resistant weeds.
“We are getting back to the way we used to farm.”