More Dicamba Details

Sorting Out the XtendiMax Label

Pam Smith
By  Pam Smith , Crops Technology Editor
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The dicamba herbicide called XtendiMax has a label, but farmers will be required to follow specific application requirements -- including specific nozzles.

DECATUR, Ill. (DTN) -- The long wait for a labeled dicamba herbicide to use on Roundup Ready 2 Xtend soybeans and cotton ended on Wednesday. The Environmental Protection Agency (EPA) announced that it is registering Monsanto's herbicide known as XtendiMax with VaporGrip Technology for the 2017 season. However, the registration comes with an array of spray application requirements.

EPA also sent a warning shot to farmers and spray applicators regarding the importance of following these measures by granting a two-year conditional registration. The agency said it would let the label expire or make necessary changes if problems with resistant weeds or pesticide drift are detected.

EPA acknowledged that XtendiMax is a different formulation than the dicamba products that were allegedly used illegally and caused damage to sensitive crops this summer. However, it also indicated investigations continue into the dicamba drift that occurred in parts of the Midsouth and Midwest. Read more….

XtendiMax is a dicamba-only herbicide product formulated with the VaporGrip additive designed to reduce volatility. The current label allows no tank mixing. Growers wishing to apply a post grass control in-season, for example, would be required to make it in a separate application pass.

However, in a DTN interview, Ryan Rubischko, Monsanto North America dicamba portfolio lead, said the EPA has "left a pathway for tank-mixing XtendiMax both with herbicides and adjuvants."

"EPA has given us a list of instructions as to what will need to be done to enable a tank-mix," said Rubischko. Each product will require testing to prove it does not adversely affect the offsite movement potential of XtendiMax. He said a list of those approved products will eventually be found at and that website will be constantly updated as products become available.

One specific spray nozzle (Tee Jet TTI11004 nozzle with a maximum operating pressure of 63 psi) has also been approved for use with the new dicamba formulation. However, Rubischko said the EPA has outlined a process to allow for additional nozzles and those, along with the pressure details, would be listed on that same educational website as they pass muster.

Other spray mitigation tactics include buffer zones to protect sensitive areas when the wind is blowing; no application from aircraft; no application when the wind speed is over 15 mph or below 3 mph; a minimum 10 gallon spray solution per acre; and boom height restrictions of no more than 24 inches above the crop canopy.

Still, farmers have already commented on Twitter that they feared worse, especially with regard to spray setbacks. Some deemed the required downwind in-field buffer of 110 feet when applying at the 0.5 lb. a.e./acre application rates and 220 feet when applying at the 1.0 lb. a.e./acre rate as "manageable."

University of Illinois weed scientist Aaron Hager told DTN his biggest concern is that spray applicators understand that herbicide volatility and physical drift are different. "The need to carefully follow label directions and keep this product physically on-target will be critical and require a lot of attention to detail both during application and cleanout of sprayers," Hager said.

"It doesn't take much of dicamba to cause damage to sensitive crops and we have a lot of sensitive crops to consider. Having a reduced-volatility formulation does not eliminate physical drift," he added.

XtendiMax herbicide is a diglycolamine (DGA) salt -- the same salt used in Clarity herbicide. Monsanto has told DTN in past correspondence that it is the VaporGrip additive that prevents the formation of dicamba acid and lowers volatility, based on company tests. However, university weed scientists have said they've not been allowed to test the new formulations to compare to older products such as Banvel and Clarity and there is no independent data.

DuPont has signed a supply agreement with Monsanto for a DGA-based dicamba plus VaporGrip called FeXapan. BASF is also awaiting registration of a dicamba herbicide to be used in-crop with Xtend crops. Branded Engenia, it is a BAPMA salt with a molecular structure said to be more effective at binding dicamba spray to plants and soil, reducing potential volatilization of the herbicide. BASF representatives told DTN they expect Engenia registration within weeks and in time for the 2017 season.

Rubischko said Monsanto is still pursuing the EPA registration of dicamba/glyphosate premix called Roundup Xtend with VaporGrip Technology.

EPA has registered the XtendiMax formula for use on dicamba-tolerant soybean and cotton for sale and use in Alabama, Arizona, Arkansas, Colorado, Delaware, Florida, Georgia, Illinois, Iowa, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia and Wisconsin.

However, some states are considering more stringent protocols. Proposals currently under review in Arkansas, for example, would prohibit dicamba sprays between April 15 and Sept. 15.

Monsanto has said it expects the seed technology will be deployed on 15 million soybean acres and 3 million cotton acres in its seed brands in 2017. The technology has also been licensed to more than 100 additional brands. DuPont Pioneer does not reveal acreage figures, but did an introductory launch of about 30 Roundup Ready 2 Xtend soybeans varieties across a broad range of maturities this year and expects to ramp that up in 2017. In addition, Syngenta will release Xtend soybean varieties in 2017 for the first time.

Canadian farmers already have access to the Xtend trait and herbicide platform for 2017. Farmers in Canada held off planting the trait in 2016, except for experimental plots, because it lacked EU import approvals at planting time. The Xtend trait now has the international approvals needed for launch.

EPA proposed this dicamba herbicide decision on March 31, 2016. EPA's final regulatory decision and supporting documents, including a response to public comments, are available in docket number EPA-HQ-OPP-2016-0187 at www.regulations.go.

Other spray considerations for XtendiMax include:

-- Do not make an application of the product if rain is expected in the next 24 hours.

-- Do not tank mix products containing ammonium salts such as ammonium sulfate and urea ammonium nitrate.

-- The maximum combined quantity of this product that may be applied for all preplant, at-planting, and preemergence applications is 44 fluid ounces (1.0 lb. a.e. dicamba) per acre per season for both cotton and soybeans.

-- The maximum application rate for a single, preplant, at-planting, or preemergence application must not exceed 44 fluid ounces (1.0 lb. a.e. dicamba) per acre for both cotton and soybeans.

-- The combined total application rate from crop emergence up to R1 must not exceed 44 fluid ounces (1.0 lb. a.e. dicamba) per acre for soybeans per year.

-- The combined total application rate from crop emergence up to 7 days' pre-harvest must not exceed 88 fluid ounce (2.0lb a.e dicamba) per acre for cotton per year.

-- All applications for both cotton and soybeans must not exceed 88 fluid ounces (2.0 lb. a.e dicamba) per acre per year.

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Pam Smith