Farm Progress

EPA has registered Enlist Duo herbicide in six states. Registration in 10 other states, including five Mid-South states, could come at the end of a 30 day comment period.

October 15, 2014

2 Min Read

The EPA is registering the herbicide, Enlist Duo in six states, with first-time ever restrictions to manage the problem of resistant weeds. The pesticide is for use in controlling weeds in Dow AgroSciences Enlist corn and soybeans, which are genetically-engineered to tolerate 2,4-D and glyphosate. Enlist corn and soybeans have also received EPA approval.

EPA is registering the herbicide in Illinois, Indiana, Iowa, Ohio, South Dakota and Wisconsin. The agency is accepting comments until Nov. 14, 2014 (30 days) on whether to register Enlist Duo in ten more states: Arkansas, Kansas, Louisiana, Minnesota, Missouri, Mississippi, Nebraska, Oklahoma, Tennessee and North Dakota.

According to a statement from EPA, the agency’s decision “reflects a large body of science and an understanding of the risk of pesticides to human health and the environment.”

EPA said its scientists “used highly conservative and protective assumptions to evaluate human health and ecological risks for the new uses of 2,4-D in Enlist Duo. The assessments confirm that these uses meet the safety standards for pesticide registration and, as approved, will be protective of the public, agricultural workers, and non-target species, including endangered species. 

“The agency evaluated the risks to all age groups, from infants to the elderly, and took into account exposures through food, water, pesticide drift, and as a result of use around homes. The decision meets the rigorous Food Quality Protection Act standard of ‘reasonable certainty of no harm’ to human health.”

While the approved formulation contains the choline salt of 2,4-D which is less prone to drift than the other forms of 2,4-D, EPA put into place restrictions to avoid pesticide drift, including a 30-foot, in-field “no spray” buffer zone around the application area, prohibiting pesticide application when the wind speed is over 15 miles per hour and only permitting ground applications.

EPA is also imposing resistance management requirements on the registrant. These requirements include extensive surveying and reporting to EPA, grower education and remediation plans. The registration will expire in six years, allowing EPA to revisit the issue of resistance. In the future, the agency intends to apply this approach to weed resistance management for all existing and new herbicides used on herbicide tolerant crops.

This assessment is the third time in recent years that EPA has evaluated the safety of 2,4-D and the safety finding is consistent with past assessments that EPA has performed for 2,4-D. EPA comprehensively reviewed 2,4-D in 2005, and once more in 2012 and now again in 2014 in response to the current application.

The EPA’s final regulatory decision document is available in EPA docket EPA-HQ-OPP-2014-0195 at

Questions and answers about this final regulatory decision are available at:

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