CHICAGO, July 22 (Reuters) - A U.S. appeals court on Wednesday ruled that Corteva Inc can continue to sell an agricultural weed killer that environmentalists said was threatening to plants and wildlife.
The decision to allow sales of Enlist Duo boosts Corteva's advantage in the farm sector a month after the same court blocked a rival herbicide sold by Bayer AG. The companies compete for sales of chemicals and seeds in the $40 billion U.S. soybean market.
Enlist Duo, a blend of the chemicals 2,4-D choline and glyphosate, is sprayed on soybeans, corn and cotton that are designed to resist it.
A three-judge panel on the 9th U.S. Circuit Court of Appeals rejected a claim from environmental groups that the U.S. Environmental Protection Agency failed to properly consider the product's volatility, or tendency to evaporate into a gas and drift away. Instead, they said the agency properly relied on studies to conclude that the volatility of 2,4-D choline salt will not cause unreasonable harm to the environment.
The court in June ruled the EPA substantially understated the risks related to the use of dicamba, a chemical found in herbicides sold by Bayer, Corteva and BASF SE. Dicamba-based herbicides are known to drift away and damage other crops that are not resistant.
Farmers and seed dealers said the two rulings could drive a shift among farmers away from dicamba-resistant Xtend soybean seeds sold by Bayer to Enlist E3 soybean seeds sold by Corteva.
"Corteva is confident in the sustainability and effectiveness of Enlist Duo," the company said in a statement.
Environmental groups criticized the court's decision.
"The research the EPA cites does not even qualify as scientific data," said Stephanie Parent, a Center for Biological Diversity attorney involved in the case.
The court found EPA failed to properly assess the harm that Enlist Duo could cause to monarch butterflies but said the error was not "serious."
Reporting by Tom Polansek; Editing by Leslie Adler