Cotton farmers finally have approval to use new dicamba formulation herbicides on tolerant varieties in 2017, with the expectation to have the 2,4-D product available “any day now,” according to industry sources at the Beltwide Cotton Conferences in Dallas.

Representatives from Monsanto, Dow AgroSciences, and BASF discussed the new technologies at the opening day Cotton Consultants Conference.

XtendiMax herbicide, Monsanto’s dicamba product to be used with XtendFlex varieties, is labeled in seven states from Arizona to Virginia, says John Fowler, Monsanto. Georgia has a 24-C registration.

“XtendiMax with VaporGrip technology decreases dicamba volatility,” he says, “and is the recommended product for XtendFlex varieties.” He urges consultants to work closely with growers on restrictions and application procedures that include a 21-day preplant and a 7-day preharvest application restriction.

Only one spray nozzle is approved, a TTI11004. Maximum and minimum application rate is 22 fluid ounces per acre over the top.

Jonathan Siebert, Dow AgroSciences, says Enlist Duo, a 2,4-D formulation, has been labeled for corn and soybeans for two years in some states. “We anticipate a label for Enlist cotton varieties any day now.” He notes that currently 23 nozzles are approved for Enlist Duo application. “That offers producers flexibility, and we are evaluating additional nozzles.”

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EDUCATION A PRIORITY

Enlist Duo with Colex-D technology reduces volatility and lessens potential drift to non-target plant species, Siebert says. “Grower education will be a priority.

Engenia, a dicamba product from BASF, received a label just before Christmas for use on ExtendFlex cotton, says BASF spokesman John Schultz. He notes that Engenia’s salt ingredient, BAPMA, “reduces volatility. It’s a heavier molecule, so it doesn’t drift as readily.”

He says timing and rate are important factors. As with the other herbicides, the application window extends from pre-emergence through seven days before harvest. “Engenia rate is 12.8 ounces. That’s the only rate approved,” Schultz says.

Other considerations include spray boom height. “The boom should be at 24 inches or less above the canopy. We have to drive that message home.”.

All three company representatives note that coverage will be crucial, using a minimum of 10 gallons per acre. “We like 15 better,” Schultz says.

Application is restricted to ground rigs only. Spray application requirements include wind speed restrictions — typically a 3 mph to 15 mph limit. The 3 mph minimum is necessary to guard against temperature inversion.

SENSITIVE CROPS

Spraying either of the products will be prohibited when a sensitive crop in an adjacent field is downwind.

Buffers also must be established for certain crops, endangered species, and other sensitive areas such as beehives. Sensitive crops include vegetables and other specialty crops, non-tolerant cotton, grapes, and others. Tank mix restrictions vary from product  to product.

Spray system cleanout will be crucial to prevent injury to non-tolerant crops sprayed following application of either the 2,4-D or dicamba formulations. Sprayer cleanout for Enlist Duo includes a single rinse if the next application is to glyphosate-tolerant corn or triple rinse for all other crops. For dicamba, cleaning recommendations include triple rinse and a detergent-based cleaner.

Industry representatives and growers have been anxiously awaiting this new technology, but now face the challenge of not overusing or misapplying the herbicides.

The three industry spokesmen say a systems approach to weed control, including pre-emerge, residual herbicides, and appropriate postemerge materials, in conjunction with the new dicamba and 2,-4-D products, will be critical to prevent weed resistance. Crop rotation and rotating chemistry with different modes of action are also part of a product stewardship program.