Soybeans Tolerant to Growth Regulator Herbicides Discussed at Breakfast Meeting

New herbicide-tolerant crops that will expand the weed control options for soybeans have been developed. However, they are not ready for the 2016 season.
The integrated pest management (IPM) Breakfast Series is organized by the MSU Extension field crops team in southwest Michigan. The meeting series runs through the end of June and is held on Tuesdays at the Royal Café in Centreville beginning at 7:00 AM. Each meeting is open to the public and includes updates of the major field crops grown in the region, including a crop and pest report, followed by a guest speaker presentation.
On May 3, Rod Stevenson from Monsanto and Dave Hillger from Dow AgroSciences discussed their respective company’s new weed control systems in soybean. They also provided updates on the progress for bringing these new products to market.
Controlling broadleaf weeds in soybeans can be a challenge, particularly with weeds that have become resistant to glyphosate and other commonly used herbicides in corn and soybean in Michigan and throughout the Midwest. Christy Sprague, MSU Extension Specialist has excellent publications on managing three of the more common herbicide-resistant weeds in Michigan: horseweed (a.k.a. marestail), common waterhemp and Palmer amaranth.
The two technologies that each of the speakers discussed add another effective herbicide Site of Action (SoA) group to current weed control systems in soybean that may help control and delay the further development of herbicide resistance. These technologies involve soybean varieties that are resistant growth regulator herbicides that have been used to control broadleaf weeds for decades. Dow AgroSciences’ Enlist Soybean allow for in-crop use of 2,4-D and glyphosate and Monsanto’s Roundup Ready 2 Xtend Soybean can tolerate in-crop applications of dicamba and glyphosate. The speakers discussed the development of new herbicide formulations for each of these active ingredients that are less prone to volatilization (i.e. vapor drift) and particle drift, decreasing the risk of injury to surrounding sensitive plants. Also explained was the Environmental Protection Agency (EPA) requirement of the inclusion of prescribed nozzles that must be used when spraying these herbicides to reduce drift potential, something that is unprecedented on herbicide labels but that is likely to be a new requirement for all new pesticide labels in the future.
The approval process for growing these soybeans involving the USDA, China and European Union is ongoing. Therefore, growers are not advised to grow these varieties in 2016. Also, the EPA has yet to register dicamba herbicide for preemergence and postemergence use in a soybean crop. However, both speakers were optimistic that their respective weed control systems would be available to growers for the 2017 season.
Eric Anderson

Michigan State University Extension

Field Crops Extension Educator – St. Joseph County


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