An appeals court has rejected the U.S. Environmental Protection Agency’s (EPA) move to overturn its own registration for Dow AgroSciences’ Enlist Duo herbicide combo.

The EPA in November had sought court approval to withdraw its previous registration for the proprietary glyphosate/2,4-D combination. The agency said it wanted to re-examine the product, which Enlist varieties of corn and soybeans are genetically modified to tolerate.

The EPA, in its court filing, had said it since learned Dow Agro was claiming Enlist Duo’s two active ingredients work better together.

Until 2014, the choline salt form of 2,4-D used in Enlist Duo — billed as less prone to drift and volatilization than other forms of 2,4-D — hadn’t been registered for any U.S. herbicide use.

EPA in November said its earlier study of Enlist Duo assumed the 2,4-D and glyphosate components didn’t have such “synergistic effects” and may have understated the product’s phytotoxicity.

But a three-judge panel from the U.S. Court of Appeals for the Ninth Circuit on Monday denied the EPA’s motion to vacate the Enlist Duo registration.

The EPA’s request to vacate came as a result of related actions against both the agency and Dow by two U.S. groups, the Center for Food Safety and the Natural Resources Defense Council.

The judges said their decision is made “without prejudice to the rights of either party to litigate that question before the agency.”

Dow Agro, in a separate statement by email, said it “agrees” with the appeal court’s decision and “will continue to work co-operatively with the U.S. EPA concerning Enlist Duo.”

Meanwhile, Dow said, “as a result of the decision, the current U.S. registration for Enlist Duo remains fully intact for all labeled uses.”

Enlist Duo, Dow Agro said in November, “continues to be available in Canada for its registered uses” and the Enlist traits in corn and soybeans are still “fully approved for cultivation in Canada.”

Apart from its uses on Enlist crops, Enlist Duo is also registered in Canada for pre-seeding and pre-emergent use on spring, winter and durum wheat, barley, rye and field corn acres. Canadian regulators approved the herbicide in May 2013, while its use in several U.S. states wasn’t approved until 2014.

Dow had already kept Enlist corn and soybeans from full Canadian commercial release until the traits were approved in the U.S., “out of respect for movement of grain between the two countries.” — AGCanada.com Network