New Dicamba Premix

DECATUR, Ill. (DTN) -- Add another dicamba herbicide to the list of approved products for use with the Xtend trait technology. The new formulation is a premix with an early-season spray window.

The Environmental Protection Agency (EPA) approved Syngenta's Tavium Plus VaporGrip herbicide on April 5. Labels are now available and reveal there are some slight differences between Tavium and the other herbicides designated for use with the Xtend trait system.

Bobby Bachman, herbicide product lead for Syngenta, confirmed during a DTN phone interview Tavium is a premix that combines a diglycolamine salt (DGA) (Group 4) dicamba, S-metolachlor (Group 15) and VaporGrip technology.

The new herbicide can be used preplant, at-plant and early post-emergence on Roundup Ready 2 Xtend soybeans and Bollgard II XtendFlex cotton. The label prohibits use of Tavium in double-crop soybeans. In Canada, it is approved as a pre-emergence product only.

Tavium is aimed at offering both contact and residual weed control. Bachman noted Syngenta studies indicate the combination offers three weeks of residual control beyond the use of dicamba alone.

DGA-based dicamba first came on the market as Clarity herbicide and is the same molecule used in FeXapan and XtendiMax herbicides, single-ingredient dicamba formulations that also deploy VaporGrip technology, designed to reduce the formation of dicamba acid.

Bachman said Tavium is a proprietary Syngenta formulation that includes a DGA-sourced dicamba. VaporGrip, an additive developed by Monsanto to reduce the formation of dicamba acid and reduce volatility issues related to dicamba, is being licensed from Bayer (the new owner of Monsanto).

EARLY CUTOFF

Beyond being a premix, the main difference spray applicators will notice is that Tavium is registered in the U.S. to be applied through the V4 soybean growth stage and through the six-leaf growth stage in cotton. That's a slightly earlier spray cutoff compared to competing products.

"The big thing we are striving for is getting the S-metolachlor to the soil surface, providing growers with good residual weed control," Bachman said. "Dicamba is in there to provide contact control."

University of Illinois weed scientist Aaron Hager has evaluated weed control and crop response with Tavium for several seasons. "Conceptually, I like the fact the product is a premix and targeted for early-season applications," said Hager.

VOLATILITY CONSIDERATIONS

The past few seasons have demonstrated the new dicamba formulations can still move despite the addition of VaporGrip technology.

Bachman said Syngenta studies with Tavium indicate this formulation will behave much like the other dicamba products registered for use with regard to volatility.

That's what Jason Norsworthy has found in University of Arkansas studies, as well. "I have worked with Tavium on weed control and volatility," said Norsworthy. "Three low-tunnel-volatility trials were conducted in Arkansas along with a large-scale field trial. In the large-field trial, Engenia and Tavium volatility were similar. Similarly in the low tunnel trials, Tavium volatility was comparable to Engenia and XtendiMax."

Bachman said best management practices are in place to help applicators keep the product on target from a physical drift standpoint. "We know from the work that has been done that off-target movement is absolutely a key and critical issue, and a topic of concern. However, we feel when these products are used properly under best management practices that growers can be highly successful at keeping them where they are intended to be applied.

"We know we want to avoid applying Tavium when sensitive crops are in the area," he said.

"Proper sprayer set-up and application is key and critical when utilizing any herbicide," Bachman added.

"For example, with Tavium and the other auxins, it's critical that applicators are using 15 gallons of water; not exceeding speeds of 15 miles per hour and making sure that boom height is less than 24 inches above the target canopy," he said. He also noted the importance of proper water volume and ultra-coarse spray droplets.

"Using those and other approved management practices, growers can get good efficacy and prolong the longevity of this technology," he added.

All of the approved and qualified tank mixes and nozzles are listed on a website and can be found here: www.TaviumTankMix.com

Applicators should not add AMS and UAN to the tank with Tavium, since they can acidify the spray solution and increase dicamba volatility. The same restriction exists for Engenia, FeXapan and XtendiMax dicamba herbicides.

In addition, weed scientists have been warning that adding glyphosate in the tank can alter spray pH and cause additional volatility issues. The most recent EPA labels urge applicators to test spray tank mixtures and maintain pH above 5.0.

"We're in a good spot with Tavium at just under 7.0 pH," Bachman said. "What we find with the auxins is when glyphosate is added, they buffer out around 5.0 pH. Obviously, the water source and other additions play a role. So it is important to understand the importance of pH with these products."

NOTE ON RESISTANCE

Weed populations with resistance to S-metolachlor have recently been identified in some states, so growers are encouraged to consider resistance as they plan a weed-control strategy.

"We know the development of weed resistance means growers can no longer just rely on one single application or single modes of action," Bachman said. He urged farmers to look to robust pre-emergence herbicide programs that contain multiple effective sites of action and followed with post products that contain multiple sites of action and residual activity.

"The premix formulation provides an easy way to reduce selection pressure on dicamba, but a system of pre- and post-emergence herbicides is still crucial," Bachman said. "Practicing sound resistance-management principles -- such as starting clean and using diversified management and agronomic practices -- will help growers be good stewards of the technology."

Spray applicators must complete auxin training to purchase and apply Tavium -- just as with all other dicamba products on the market. Auxin training stretches across brands, but Bachman noted that states do differ with regard to rules, regulations and some specific label language.

Learn more about Tavium and find the complete EPA-approved label at: http://www.syngenta-us.com/…

Pamela Smith can be reached at Pamela.smith@dtn.com

Follow her on Twitter @PamSmithDTN

(CZ/SK/BAS)