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 Part 2
Change is essential
“Growers must change weed control practices,” says Helena Chemical Company’s Michael Kenty, “or risk losing yield and profit.”
Differentiating between resistant and hard-to-control weeds is a first step. “If you suspect resistance, get a sample and have it analyzed,” he says. “But also understand that some weeds are hard to control with certain products, morningglory on Roundup, for instance.”
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“We have to pull out all the tools we can,” says Jacob Reed, BASF. He recommends four top practices to manage resistant weeds.
- Identify the weed. Know when specific weeds emerge and how they grow so you can select the best herbicide and time applications appropriately.
- Use multiple sites of action. Locate where the herbicide affects the weed. That information helps with herbicide selection and timing.
- Layer residual herbicides to provide overlapping protection.
- Don’t let weeds escape and produce seed. Next year’s weed control program starts now.”
Reed says famers most likely “will have resistant weeds somewhere on their farms.”
Russ Perkins, Bayer CropScience, says Liberty offers an alternative to Roundup but requires close attention to application timing and method to work effectively. “Follow our STOP system: Start early; Target small weeds (less than three inches tall—1 inch to 2 inches is better); Optimize coverage. Use the correct rate of Liberty –on LibertyLink cotton varieties only—and cover the entire plant. Water volume should be 15 to 20 gallons per acre; Pair Liberty with residuals.”
- Optimize and
- Pair = STOP.
“We kept resistance away for years with yellow herbicides,” Perkins says. “We have to get back to that.”
Tank mixing Liberty and Roundup on varieties tolerant to both products, is not effective. “We need to make separate applications.”
Enlist coming in 2016
Dow likely will have new technology available for cotton (also corn and soybeans in Texas) next year with the Enlist system.
“Enlist Duo is a different product (from 2, 4-D),” says Dow’s Ralph Porter. “It has low volatility and is stable.” Dow also has several new products for the wheat market, Quelex and Arylex.
“Wheat is an important crop for the Southwest with 20 million acres in Oklahoma, Kansas and Texas. Some 10 million acres are treated for broadleaf weeds and 2 million acres are rotated to another crop. Producers must be aware of plant-back restrictions, but numerous products are good options for weed control in rotation.”
Jack Lyon, DuPont, recommends cotton producers start with a clean seedbed. “We need to use multiple modes of action and remember that different weed species emerge at different times, so we may need to make a second trip.”
Farmers should start with a burndown in late February or early March. “A lot of products are available. It’s better to apply a burndown material early than too late. Producers need to get out in front of resistant weeds.
“Preplant herbicides work better with mechanical incorporation. Chemigation will work on fields with residue.”