Reuters –– U.S. farmers suing Syngenta over its decision to commercialize a genetically modified (GMO) strain of corn before China approved importing it sought court approval on Monday of a record US$1.51 billion settlement with the Swiss seed company.

The deal covers U.S. corn producers, grain handling facilities and ethanol plants nationwide that sold corn priced after Sept. 15, 2013, according to a filing in Kansas federal court. Lawyers for the plaintiffs said in a statement that they believed the deal to be the largest agricultural class action settlement in U.S. history.

“We are very pleased with this outcome,” they said.

Cargill is still pursuing separate claims against Syngenta and is not part of the settlement. Archer Daniels Midland (ADM) announced it reached a separate settlement with Syngenta in February.

Syngenta, now owned by Chinese chemical company ChemChina, could not immediately be reached for comment.

The settlement was first reported in September, but its details were not made public until Monday’s filing.

The farmers’ class action lawsuit, which was certified in 2016, concerns Syngenta’s 2010 decision to sell a strain of insect-resistant GMO corn called Agrisure Viptera in the U.S.

Lawyers for the corn farmers said Syngenta negligently commercialized the seeds before obtaining import approval from China, then a major buyer of U.S. corn.

Chinese authorities ultimately rejected millions of tonnes of the U.S. corn imports before the country later approved Viptera for import in December 2014.

More than 90 per cent of corn grown in the U.S., the world’s top supplier, is genetically engineered, according to the U.S. Department of Agriculture.

The loss of the Chinese market caused U.S. corn prices to plummet, the farmers’ lawyers said.

Syngenta denied wrongdoing. It said at the time that no company had ever delayed launching a U.S.-approved corn product in the U.S. just because China had yet to approve its import.

It also said the decline in sales to China was offset by exports to other countries.

In addition to the nationwide class of farmers, several state classes were certified. One of those went to trial, resulting in a US$217.7 million for more than 7,000 Kansas farmers in June.

— Reporting for Reuters by Brendan Pierson in New York.