UPDATED, Nov. 25, 2015 — Chicago | Reuters — The U.S. Environmental Protection Agency (EPA) is seeking court approval to withdraw registration of Dow AgroSciences’ herbicide Enlist Duo, as the agency studies new information regarding the product’s impact on non-target plants, according to court documents filed late Tuesday.
The EPA approved the herbicide for sale and use in several U.S. states more than a year ago, but later found that its assessment of the product’s two active ingredients was incomplete.
Enlist Duo is among a group of next generation herbicides designed to combat weeds resistant to glyphosate, a widely used herbicide in the United States and the active ingredient of Monsanto’s Roundup.
Enlist Duo, which combines 2,4-D with glyphosate, is meant for use on corn and soybeans that have been genetically altered to tolerate it while killing surrounding weeds that can drag down crop yields.
The EPA said it discovered claims by Dow AgroSciences, the registrant of Enlist Duo, in its patent filings that the two active ingredients work better in combination, according to a court filing seen by Reuters. The EPA’s study had assumed the components did not have such “synergistic effects.”
“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 court filing said.
Dow Chemical said it was working with the EPA to provide further assurances for Enlist and it expects a “prompt resolution of all outstanding issues.”
Health Canada’s Pest Management Regulatory Agency approved Enlist Duo in 2013, a year after Enlist corn and soybeans picked up Canadian approval.
The herbicide’s Canadian approval covers its use to control annual and perennial weeds in Enlist field corn and Enlist soybeans, and in summerfallow. It can also be applied pre-seeding or pre-emergence in spring wheat, winter wheat, durum, barley, rye and field corn.
Both 2,4-D and glyphosate have long been available individually from other ag chem companies, but Dow has said its “proprietary blend” of glyphosate with 2,4-D choline offers “advanced technology” to reduce drift and “off-target movement” of its herbicide.
Monsanto said it is not worried that its next generation herbicide platform Xtend, which combines the herbicide dicamba with glyphosate, would be similarly targeted by EPA.
“Monsanto’s patent submissions have not made claims of synergistic activity between glyphosate and dicamba. We believe we have submitted a regulatory data package that supports approval of our product,” Monsanto spokesperson Sara Miller said.
— Karl Plume reports on agriculture and ag commodity markets for Reuters from Chicago. Additional reporting for Reuters by Sneha Banerjee in Bangalore. Includes files from AGCanada.com Network staff.