Mexico on Saturday, June 24, imposed a 50% tariff on white corn imports. The tariff is expected to remain in place through the end of the year.

It’s a decision that Mexican President Andrés Manuel López Obrador said can boost national production and prevent imports of genetically modified corn.

The measure comes amid a trade dispute between Mexico and the U.S. and Canada over genetically modified corn. Mexico wants to restrict genetically modified white corn and eventually yellow corn, which is used for animal feed.

In 2022, the U.S. exported 13.8 million tons of yellow corn and 1.6 million tons of white corn to Mexico. This is the largest foreign market for U.S. corn, and nearly all of it was grown from genetically engineered seeds.

The tariff, however, goes against the U.S.-Mexico-Canada free trade agreement and could further complicate the trade dispute already underway between the countries.

Both the U.S. and Canada have expressed concerns about Mexico’s restrictions threatening scientific progress.

“We fundamentally disagree with the position Mexico has taken on the issue of biotechnology, which has been proven to be safe for decades,” U.S. Secretary of Agriculture Tom Vilsack said in early June when the U.S. officially requested dispute settlement consultations with Mexico. “Through this action, we are exercising our rights under USMCA while supporting innovation, nutrition security, sustainability, and the mutual success of our farmers and producers.”

Canada sided with the U.S. on the issue.

“The Government of Canada is committed to science-based decision-making and keeping food, feed and the environment safe, while supporting the ability of our farmers, workers and exporters to succeed in an innovative and sustainable agricultural sector,” Bibeau’s office wrote in a statement. “Canada shares the concerns of the U.S. that Mexico’s measures are not scientifically supported and have the potential to unnecessarily disrupt trade in the North American market.”

A complete ban on biotech corn would cause the U.S. economy to lose about $74 billion in economic output and cause the price of corn in Mexico to inflate by an average of 19% over a 10-year period, according to a World Perspectives report.