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U.S. pulls Enlist Duo registration pending more study

The herbicide is still registered in Canada and will be introduced to 
Manitoba farmers on a limited basis next spring

Dow AgroSciences still plans to introduce Enlist Duo to Manitoba farmers next spring despite concerns in the U.S. that resulted in the Environmental Protection Agency (EPA) withdrawing its registration.

The EPA is requiring more studies into the product’s phytotoxicity, saying Enlist Duo might do more harm to non-target plants than it first believed after reading patent data that says its ingredients — glyphosate and 2,4-D — killed plants better when combined than when applied separately.

But the product continues to be available in Canada and some Manitoba farmers will be using Enlist Duo in Enlist-tolerant corn next spring, Larolee Orr, Dow AgroSciences’ communications leader, said in an email last week.

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“We will have a managed introduction in Manitoba in 2016,” she said. “The introduction will take place under our Canada Field Forward program, which provides growers an exclusive opportunity to experience new Dow AgroSciences technologies before they are widely available.

“Growers will manage the technology according to the herbicide label and product use guide, and will employ best management practices from Dow AgroSciences. Farmers participating in the program will be engaged with Dow AgroSciences throughout the season as they evaluate and steward the technology on their farms.”

Dow AgroSciences is working to develop early-maturing Enlist soybeans before introducing them in Manitoba, Orr added.

Enlist Duo was registered in Canada in 2013 for control of annual and perennial weeds and use in Enlist field corn, Enlist soybeans, summerfallow and prior to seeding or after seeding, but before crop emergence, in spring and winter wheat, durum, barley, rye and field corn.

Health Canada, which oversees Canada’s Pest Management Regulatory Agency, said it regularly reviews all new health and safety information on products.

“Should new information emerge the department will evaluate the data and assessments. A pesticide is registered in Canada only when a rigorous science-based risk assessment determines that it will not harm human health or the environment and that it has value as a pest control product,” a department official said in an email.

Dow Chemical Company, which owns Dow AgroSciences, said in a news release Nov. 25 it’s “working quickly” to provide the information the EPA needs.

Enlist corn and soybeans have been genetically modified to tolerate glyphosate, a non-selective herbicide and 2,4-D, which kills a wide variety of broadleaf plants and can damage non-modified corn.

Dow AgroSciences says Enlist Duo can help farmers control certain glyphosate-resistant weeds and glyphosate-tolerant crops. For example glyphosate-tolerant volunteer canola is killed when sprayed with 2,4-D.

Enlist Duo was registered in some U.S. states more than a year ago. But the EPA announced in a court filing in connection to a lawsuit aimed at blocking the product’s commercialization that it had discovered new data.

“The information suggests that EPA’s analysis may have understated the phytotoxicity of the product. Therefore EPA can no longer be confident that Enlist Duo will not cause risks of concern to non-target organisms, including those listed as endangered,” the EPA court filing said.

The Associated Press reported the EPA said it “might not have issued the existing registration had it been aware” of the new information.

The EPA asked the court for the authority to reverse its decision while it reconsiders Enlist Duo, including whether or not to widen buffer zones to protect non-target plants, AP said. The EPA’s registration required farmers to leave a 30-foot downwind buffer around field edges.

“EPA is seeking a remand because this new information could lead EPA to a different decision on the restrictions for using Enlist Duo,” Ag Insider reported court documents as stating. “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.”

Environmental groups claim the EPA failed to properly assess Enlist Duo in the first place.

“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,” Dow AgroSciences president and CEO Tim Hassinger said in a release.

“It’s possible that we could see some changes to use conditions on the existing Enlist Duo label,” he said. But he said the company expects the product will return to the marketplace in time for the 2016 growing season.

About the author

Reporter

Allan Dawson

Allan Dawson is a reporter with the Manitoba Co-operator based near Miami, Man. Covering agriculture since 1980, Dawson has spent most of his career with the Co-operator except for several years with Farmers’ Independent Weekly and before that a Morden-Winkler area radio station.

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