The EPA is registering the herbicide Enlist Duo with first-time-ever restrictions to manage the problem of resistant weeds. 

The Dow AgroSciences' herbicide is for use in controlling weeds in corn and soybeans genetically engineered to tolerate 2,4-D and glyphosate. The agency’s decision reflects a large body of science and an understanding of the risk of pesticides to human health and the environment. 

The herbicides 2,4-D and glyphosate are two of the most widely used herbicides in the world for controlling weeds. Dozens of other countries including Canada, Mexico, Japan and 26 European Union Members have approved these pesticides for use on numerous crops and residential lawns.

EPA 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. 

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. The agency has also put in place restrictions to avoid pesticide drift, including a 30-foot, in-field “no spray” buffer zone around the application area, no pesticide application when the wind speed is over 15 mph, and only ground applications are permitted. This action provides an additional tool for the agricultural community to manage resistant weeds.

To ensure that weeds will not become resistant to 2,4-D and continue increased herbicide use, EPA is imposing a new, robust set of 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 the 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.

EPA is registering the pesticide in six states: Illinois, Indiana, Iowa, Ohio, South Dakota and Wisconsin. The agency is accepting comments on whether to register Enlist Duo in 10 more states: Arkansas, Kansas, Louisiana, Minnesota, Missouri, Mississippi, Nebraska, Oklahoma, Tennessee and North Dakota. 

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

With the EPA's decision to register Enlist Duo, the entire Enlist Weed Control System has now been approved by federal regulatory authorities. The Enlist corn and soybean traits were deregulated by the Department of Agriculture on Sept. 17, 2014. Dow announced it will release its 2015 market intentions for Enlist in the coming weeks.