ROCKVILLE, Md. (DTN) -- Growers purchasing soybean seed based solely on weed control are missing a key component of the decision, warn university scientists. Yield and regional performance should also factor into the equation.
This is the first year independent yield data has become available on dicamba-tolerant Roundup Ready 2 Xtend soybeans.
Lack of import approvals kept the trait concentrated in company plots and in the hands of selected growers prior to this season. Now some university tests are starting to roll in after Monsanto, DuPont Pioneer and a handful of other licensees commercialized Roundup Ready 2 Xtend soybeans for the first time in 2016.
So far, these university trials have not found any significant yield bumps from the Xtend trait alone. In field trials from the Universities of Wisconsin and Minnesota, Xtend varieties tended to yield a bushel or two lower on average.
When University of Wisconsin agronomist Shawn Conley crunched the numbers for Wisconsin Soybean program's field trials, he found that Roundup Ready 2 varieties out-yielded Xtend varieties by 1.8 bushels per acre on average. The Wisconsin trials included 200 Roundup Ready 2 varieties and 47 Xtend varieties. "It may partly just be where they are in their germplasm pool in terms of releasing varieties," Conley told DTN.
Likewise, in a smaller soybean performance trial from the University of Minnesota, IPM specialist Fritz Breitenbach found that Xtend soybeans produced an average yield of 72.8 bushels per acre, more than two bushels below the 75.1 bpa average yield of the Roundup Ready varieties. The field trial included 14 Xtend varieties and four Roundup Ready varieties.
"We were happy to see there is not a major [yield] drag, but we didn't see a huge advantage either," Breitenbach said of the Xtend varieties.
In his blog, the Soy Report, Conley urged growers to consider more than the latest herbicide trait technology when picking soybean varieties for 2017.
"New doesn't always mean it is automatically better," he wrote. "Remember every variety must stand on its own." He urged growers to scrutinize independent trial data and look for varieties that perform consistently well across geographies and environments and hold the traits you need in your region.
For many growers, that will include herbicide-tolerant technologies, such as Monsanto's Xtend soybeans, Liberty Link soybeans and possibly Dow AgroSciences' Enlist soybeans, engineered to tolerate 2,4-D, glyphosate and glufosinate. Enlist soybeans are not yet commercially available because they still lack import approvals. Dow AgroSciences has told DTN that upon import approvals, Dow AgroSciences brands and licensees will sell soybean varieties with the Enlist trait and the trait will be broadly licensed to other seed companies.
Glyphosate-resistant weed issues in a field, which theoretically could be cleaned up with new dicamba herbicides approved for use on the Xtend seeds, could offset any lower yield potential of those seeds.
Just keep in mind that these technologies include "a stack of herbicide traits and not yield traits (i.e... these traits protect yield, not enhance yield)," Conley wrote. "Remember this point with all pest management traits!"
Monsanto Product Communications Lead Kyel Richard said 2016 harvest data for the company's brands is still being assessed. "Overall across the U.S. we've gotten strong reports in terms of yields," he said. Earlier this year, Miriam Paris, Monsanto's U.S. Soybean Marketing Manager, said the higher yield potential of the new Xtend soybeans factored into the company's decision to commercialize in 2016, despite the fact there was no approved dicamba-based herbicide for use in-crop at that time.
"We've been developing Xtend soybeans for over a decade and breeding with them for eight years," Paris said, during a Missouri forum in Portageville. "All of our engine from a breeding standpoint is in Xtend soybeans." She said the new germplasm offers a 2.5-to 7-bushel-per-acre yield advantage above Roundup Ready 2 Yield varieties available today.
DuPont Pioneer spokesperson Susan Mantey told DTN that Pioneer-brand Xtend soybeans for 2017 are still in the advancement process and more performance information should be available in December.
Both Conley and Breitenbach urged growers to manage their expectations when considering new herbicide-tolerant varieties such as Xtend and prepare to rotate it with other traits to avoid resistance.
"Dicamba is used fairly extensively in corn, so weeds have been exposed to for it a long time," Breitenbach warned. "When I started over 30 years ago, we were using it. Now it's going to be used extensively in both crops."
"All of the data and models I have seen suggest that the dicamba-tolerant crops' shelf-life will be much shorter than the original Roundup Ready if we don't manage this technology correctly," Conley added in his blog.
See the results of the University of Minnesota performance trial here: http://bit.ly/… and Conley's blog on the University of Wisconsin results here: http://bit.ly/…. Growers can also find some independent soybean variety performance data from the Farmers Independent Research of Seed Technologies (FIRST) group, found here: http://www.firstseedtests.com/…
Emily Unglesbee can be reached at Emily.firstname.lastname@example.org
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