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Research Highlights
Dicamba Renewal Clarifies Seed Options

Photo: United Soybean Board

By Daniel Lemke

In June, the U.S. Court of Appeals for the Ninth Circuit issued a decision that vacated the registrations of three dicamba herbicides: XtendiMax from Bayer, Engenia from BASF and FeXapan from Corteva. The ruling left soybean farmers who had already planted dicamba-tolerant varieties in the lurch. The Environmental Protection Agency (EPA) did allow the use of existing dicamba herbicide stocks for 2020. 

Now an October ruling by the EPA has given farmers more clarity by extending the dicamba label for over the top (OTT) use in soybeans on dicamba-tolerant (DT) soybeans through 2025, providing certainty to American agriculture for the upcoming growing season and beyond.

To manage off-site movement of dicamba, EPA’s 2020 registration features additional control measures, including requiring an approved pH-buffering agent to be tank-mixed with OTT dicamba products prior to all applications to control volatility. The registration requires a downwind buffer of 240-feet and 310-feet in areas where listed species are located. The label prohibits OTT application of dicamba on soybeans after June 30. The label and use directions were also simplified so that growers can more easily determine when and how to properly apply dicamba.

Some farmers made seed-purchase decisions for 2021 without knowing if dicamba-tolerant varieties would be available.  

Carl Peterson, Peterson Farms Seed President

“The last few years, we’ve seen folks transitioning away from dicamba in pockets,” says Carl Peterson, president of Peterson Farms Seed, Harwood, North Dakota. “Some of that transition is due to the challenges with dicamba application and other systems being easier to work with. The cancellation accelerated the transition, but it hasn’t necessarily changed the direction.”

Peterson states that many farmers who weren’t willing to risk waiting for a possible dicamba label renewal are shifting to the Enlist or Liberty varieties. 

Weed Driven 

Prevailing weed concerns are a driving factor behind which herbicide and seed tolerance platform farmers choose. In the southeast corner of the state, waterhemp and ragweed tend to be the problematic weeds while kochia is the most troublesome weed across northern and western North Dakota. 

Peterson explains that the Enlist platform, which uses 2,4-D, is less effective on kochia than the Xtend platform which uses dicamba. 

“What we’re seeing is growers in areas where kochia is an issue have planned to stick with the Xtend platform, hoping for label approval,” Peterson says. 

Keith Peltier, Proseed General Manager

Proseed General Manager Keith Peltier, Harvey, North Dakota, states that most farmers don’t make firm seed orders until the combines are parked for the winter, so many growers took a wait-and-see approach. 

He agrees that the weed-control platform of choice is largely based on weed-management needs. 

“Kochia is a western and northern challenge, so farmers there are sticking with the Xtend platform,” Peltier says. “In the East where waterhemp is an issue, Enlist and Liberty are what guys are ordering. If farmers have a really a big weed concern, then the platform plays more than the yield, especially if you have to go over the top. If there’s a big weed concern and farmers aren’t able to do any pre-emerge herbicide applications, then, yes, the platform is essential even if you get less yield.”

Peltier believed that a dicamba label would be approved for soybean use in 2021 and he wasn’t alone. Bayer had a Plant with Confidence offer that, if a label for dicamba wasn’t adopted by February 2021, Bayer would support farmers who chose the Roundup Ready® Xtend Crop System for their 2021 planting needs by providing farmers with a $7-per-unit price reduction for qualifying Roundup Ready 2 Xtend® soybeans and a $3-per-unit price reduction for qualifying XtendFlex® soybeans.

If farmers plant 50 million acres of Xtend soybeans, the program could have cost Bayer as much as $350 million if a label is not approved. “That was a big bet,” Peltier states. 

Yield Matters

While seed selection for weed management is important, yield matters, too. “I’ve never made any money growing weeds,” Peterson explains. 

Peterson says that, regardless of the trait platform farmers choose, yield is determined by the seed genetics, not the trait. 

Photo: United Soybean Board

“It’s important to understand that the trait has nothing to do with yield. It’s the other genetic components,” Peterson explains. “There are very good Xtend lines for most maturities; there are very good Enlist lines for most maturities. We encourage growers to pick the system they want to work with and then pick the variety that fits. I think that’s effective.”

Peterson Farms Seed operates the largest independent, replicated testing program in the region. Peterson says that the data show no difference across platforms for yield and performance, provided the proper resistance genes are in place if a field has problems such as iron deficiency chlorosis, soybean cyst nematode or phytophthora.

“Farmers do look at how varieties are performing. If, for some reason or other, one platform didn’t perform in their area, that can impact which platform guys want,” Peltier states.  

Stewarding Tools

As herbicide resistance continues to be an issue for agriculture, the proper use of available weed management tools remains a concern regardless of the platform that farmers employ. 

“Resistance is going to continue to show up,” Peterson says. “Dicamba is really effective against kochia, until dicamba and Roundup-resistant kochia becomes prevalent, and that will happen, it’s just a matter of when. It’s important for growers to think about their weed control strategies in a more holistic manner, including crop rotation. We need to fight this with everything we’ve got because resistance is going to continue, and it’s going to be a huge problem.”

Bayer’s Xtendflex soybeans are now ready for commercial launch in the U.S. and Canada in 2021, following September’s trait approval from the European Union. Xtendflex soybeans tolerate over-the-top application of glyphosate, dicamba and glufosinate. Peterson and Peltier say that the variety will offer farmers another option, but currently, there aren’t varieties available in the relative maturity that is needed for North Dakota’s growing season.

“I’m not sure it will have a big impact this year, but certainly, if there is a renewed over-the-top dicamba label, that’s a good package. If you can successfully use dicamba early in the season and then come back on some of those other weeds with a good shot of Liberty later, that could be pretty effective weed control,” Peterson states. 

“In our opinion, choices in Xtendflex aren’t as good as what we have in the Enlist platform or Xtend platform,” Peltier explains. “But looking at our plots, it looks like the next release candidates will be a step up, so we should have more Xtendflex opportunities next year.” 

Both Peterson and Peltier say that their companies offer a full range of varieties and trait packages in order to meet farmers’ needs, regardless of the renewed dicamba label.

Photos courtesy of Peterson Farms Seed and Betsy Armour