United States pulls plug on 2,4-D-glyphosate spray registration

Thursday, November 26, 2015

by BETTER FARMING STAFF

A dual-action herbicide whose registration the American Environmental Protection Agency wants to pull remains for sale in Canada, its manufacturer has said.

“Enlist Duo continues to be available in Canada for its registered uses,” states a Dow AgroSciences, Canada news release issued early Thursday morning.

In Canada, the pesticide is used to control weeds in field corn and soybeans that have been genetically modified to resist the impact of its two active ingredients: a low volatile 2,4-D and glyphosate. It is also licensed for summer fallow and spring pre-seeding or pre-emergence application on spring and winter wheat varieties, barley, rye and field corn.

Enlist Duo is among a new generation of products touted as a way to tackle growing resistance in weeds to glyphosate herbicides.

According to the Health Canada Pest Management Regulatory Agency pesticide product information database the product’s registration expires at the end of 2018. No review of the product is scheduled.

On Wednesday, a spokesperson media relations officer at Health Canada said the department would issue a statement response to questions to Better Farming today.

UPDATE: 5:55 p.m. Thurs. Nov. 26, 2015 “We continue to monitor the actions of regulators in other jurisdictions, such as the EPA, as well as review scientific studies, and health and safety data,” says a Health Canada statement emailed Thursday by Sylwia Krzyszton on behalf of André Gagnon, media relations officer. “Should new information emerge, the department will evaluate the data and assessments.” END OF UPDATE

The EPA filed a court motion to pull the product’s registration yesterday.

In an emailed statement the agency says the action was precipitated by the receipt of new information from Dow AgroSciences “that suggests two active ingredients could result in greater toxicity to non-target plants. Dow had not provided this information to EPA prior to EPA issuing the Enlist Duo registration.”

When the agency approved the product in 2014 for use in six states (it’s now approved for use in 15 states) on GM soybeans and corn, environmental groups protested, claiming it presented risks to monarch butterflies and small animals.

The agency and Dow subsequently faced legal challenges by the Center for Food Safety, the Natural Resources Defense Council, Inc. and other non-profit groups. Those challenges have been ongoing, and it was in connection with these that the agency filed its motion with the U.S. Court of Appeals for the Ninth Circuit.

In the motion, the agency says that before registering the product “the issue of synergism” between the product’s two ingredients had been addressed “by evaluating data on the chemicals individually as well as with formulation-specific information.” The agency found the mixture did not show “a greater toxicity compared to either parent compound alone.”

The pre-registration review lead to the conclusion that since there was “no indication of synergism” in the product’s impact on mammals, freshwater fish, and freshwater invertebrates, “it is reasonable to assume there are no synergistic interactions for the taxonomic groups that were not tested, including plants.”

However, the agency says in its motion that it recently discovered Dow had made claims of “synergistic herbicidal weed control” in 2013 provisional and 2014 non-provisional U.S. patent applications for the product.

The agency is still evaluating “extensive information” provided by the company. “The agency can no longer represent to the Court that its conclusions were correct regarding whether issuance of the registration met the standard in FIFRA (Federal Insecticide, Fungicide and Rodenticide Act) and whether the buffer zones included in the registration support the finding that the registration will have no effect upon threatened or endangered plant species,” the motion says.

The agency says in its emailed statement the new information could lead to new restrictions for using the product. “Specifically this could result in changes to the width around application areas of no-use buffer zones that EPA imposed to protect unintended plants, including those listed as endangered.”

In the company’s news release, Dow AgroSciences President and CEO Tim Hassinger says “we believe the questions that have been raised about any potential synergy between 2,4-D choline and glyphosate can be promptly resolved in the next few months, in time for the 2016 crop use season.”

Hassinger acknowledges the possibility that there could be some changes to the product’s use conditions. “However, based on the ongoing dialogue with EPA, we do not expect these issues to result in the long-term cancellation” of the product.

The release claims evaluations of potential synergy between the ingredients of herbicides are common within the industry, and the agency “has not used observations of potential synergy in mixtures as a basis for regulatory action.” The company also claims that it’s common practice in the industry to file patent applications on “mixtures, without there being any connection to EPA’s regulatory process.”

According to a 2013 Dow AgroSciences news release, Canada was the first country to allow the use of Enlist Duo. What makes the product “unique,” the release says, “is that it features near-zero volatility, minimized potential for drift, lower odour, and better handling characteristics.” BF