MEXICO CITY (Reuters) - A ban on planting genetically modified corn in Mexico is likely to continue for years as a slow-moving legal battle grinds on, said a top executive of U.S.-based seed and agrochemical company Monsanto Co.

A trader works at the post where Monsanto Co. is traded on the floor of the New York Stock Exchange (NYSE) in New York City, U.S., August 25, 2016. REUTERS/Brendan McDermid/File Photo

Last week, a Mexican court upheld a late 2013 ruling that temporarily halted even pilot plots of GMO corn following a legal challenge over its effects on the environment.

“It’s going to take a long while for all the evidence to be presented,” Monsanto regional corporate director Laura Tamayo said in an interview. “I think we’re talking years.”

The impasse comes as yellow corn imports are expected to rise by more than a fifth next season on higher production costs and a weak peso, from about 15 million tonnes in the 2016/2017 cycle that ends in March.

While Mexico is self-sufficient in white corn used to make the country’s staple tortillas, it depends on imports of mostly GMO yellow corn from the United States for its livestock.

Several years ago, Monsanto submitted two applications for the commercial planting of GMO corn in Mexico. Both sought 700,000 hectares (1.7 million acres) in the northwestern state of Sinaloa, the country’s largest corn-producing area.

Both applications are still pending for Monsanto, the subject of a $66 billion takeover by Germany’s Bayer AG.

Mexico is the birthplace of modern corn, domesticated about 8,000 years ago and today the planet’s most-produced grain.

If new U.S. President Donald Trump upends the North American Free Trade Agreement as he has threatened and U.S. supplies are not longer available, Tamayo said Mexico might have to look to other major corn producers, like Argentina and Brazil.

Prominent Mexican politicians, including former President Felipe Calderon, say the nation should consider ending purchases from U.S. corn producers in favor of Brazil and Argentina if Trump applies new taxes on Mexican exports to its northern neighbor.

“But there’s no magic wand to do that,” she said. It would be “disastrous” in the short term to source from new South American suppliers since that would mean higher transport and other costs, she added.

To boost both yellow and white corn output in the near term, Tamayo said Monsanto was about a year and half away from introducing what it dubs “nano corn,” a conventional hybrid variety that she says is about 20 percent more productive.

The smaller, shorter plant with less foliage aims to divert more growth into the actual fruit, said Tamayo, who previously worked for Coca-Cola Co and commodities trader Cargill.

Monsanto’s main business in Mexico is developing and selling conventional corn seeds and vegetable seeds, but Tamayo says the company is determined to defend the benefits of genetically modified crops on scientific grounds.

Nevertheless, she noted that for years Monsanto did not see the need to persuade consumers and focused exclusively on convincing farmers to buy its products, allowing some environmental organizations to dominate the debate.

Critics say genetically modified corn plantings will contaminate age-old native varieties and that toxins designed to protect the GMO grain against pests may be linked to elevated insect mortality.

“We made a mistake; it’s just that simple,” Tamayo said. “For 18 years we didn’t explain (to the consumer) what is biotechnology, what’s it for and why it’s safe.”