WASHINGTON, March 11, 2015 – During a recent meeting of the National Research Council, which is conducting a study examining genetically engineered (GE) crops and food, an Environmental Protection Agency official described the agency’s new precautions for Dow AgroScience’s Enlist Duo product, the first herbicide for which EPA requires a weed resistance management plan.

Bill Jordan, deputy director at EPA’s Office of Pesticide Programs, noted that the agency is imposing new obligations on the company, and “if it does not follow through EPA has the legal authority to terminate the registration,” which EPA approved in October.

Enlist Duo, a dual herbicide that includes a blend of glyphosate and 2,4-D choline, is part of the Enlist Weed Control System, a herbicide-tolerant trait technology for corn and soybeans. The herbicide will be launched in conjunction with the stewarded introduction of Enlist corn and seed production of Enlist soybeans in 2015.

“Continued registration of Enlist will depend on successfully controlling herbicide resistant weeds,” according to EPA’s evaluation. The registration will expire in six years, when EPA will review the management plan’s results. In the future, any herbicide products for use on tolerant crops will fall under similar EPA programs.

EPA’s terms of registration require the company to:

·       Develop a stewardship program and training programs and educational materials for users.

·       Investigate cases of non-performance.

·       Develop remediation plan for use if resistance is expected (Dow must take steps to control and prevent the spread of likely resistant weeds, and thorough follow up is expected to make sure a problem is addressed.)

·       Report annually to EPA likely and confirmed resistance (This must include enough information to describe the nature and extent of infestation. Also, EPA says early notification is important to allow time to respond to the problem.)

The new regulations are not due to concern about the product’s safety, but to the potential for evolution of weed resistance. Jordan said EPA tested for the safety of the herbicide in instances of oral and skin contact and inhalation.

“We assumed every acre of corn and soybean would be treated and examined whether that would be safe,” he said, noting that EPA’s review found no reason for concern. EPA also found no negative effects in instances of drift or application on lawns.

However, weed resistance is a different matter. Jordan said the massive spread of weed resistance to the glyphosate herbicide in the U.S. shows the chemicals need to be managed more carefully. Acres with resistant weeds doubled in the U.S. between 2009 and 2013, now numbering around 70 million, according to agriculture industry estimates.

“Evolutionary biology leads one to expect that continued, large-scale use of this compound can contribute pressures that result in weed resistance,” Jordan said, regarding Dow’s new product. “We expect the use of Enlist Duo to lead to considerable expansion of use of 2,4-D.” EPA’s label requirements warn growers to avoid pesticide drift, and require a 30-foot “no-spray” buffer zone around the application area. Pesticide application is also banned when the wind speed is over 15 mph. The agency also recommends, but does not require, growers to scout fields before, during and after applications for resistant weeds.

A Dow spokesperson said all of the elements included in EPA’s registrant requirements are new. 

“With regard to our Enlist system, putting together a comprehensive stewardship program was front and center as we developed our plans over the last several years,” Dow stated. “We worked with the EPA to refine and develop a herbicide resistance management plan acceptable to stakeholders.”


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