By MARY CLARE JALONICK, Associated Press

WASHINGTON (AP) — Unregulated genetically modified wheat has popped up in a second location in the United States, this time in Montana, the Agriculture Department said Friday.

No genetically engineered wheat has been approved for U.S. farming, and the discovery of unapproved varieties can pose a potential threat to U.S. trade with countries that have concerns about genetically modified foods.

USDA said Friday that the incident is on a smaller scale than a similar finding in Oregon last year that prompted several Asian countries to temporarily ban U.S. wheat imports.

The herbicide-resistant wheat was found on one to three acres in Montana, while the GMO plants found in Oregon were spread over more than 100 acres. And the plants were found at a university research center in Huntley, Montana, where GMO wheat was legally tested by seed giant Monsanto 11 years ago. The plants in Oregon were found in a field that had never conducted such tests, prompting questions about how it got there.

The department said it is investigating the discovery of the Montana wheat. USDA has said the wheat would be safe to eat but that none of it ever entered commerce.

In a final report also released Friday, USDA said it believes the GMO wheat in Oregon was an isolated incident and that there is no evidence of that wheat in commerce. The report says the government still doesn't know how the modified seeds got into the fields.

The discovery of the GMO wheat in Oregon prompted Japan and South Korea to temporarily suspend some wheat orders, and the European Union called for more rigorous testing of U.S. shipments.

Monsanto Co. suggested last year that some of the company's detractors may have intentionally planted the seeds. Robb Fraley, Monsanto's executive vice president and chief technology officer, said in June 2013 that sabotage is the most likely scenario, partly because the modified wheat was not distributed evenly throughout the field and was found in patches.

"It's fair to say there are folks who don't like biotechnology and would use this to create problems," he said then.

Bernadette Juarez, who oversees investigative and enforcement efforts for USDA's Animal and Plant Health Inspection Service, said the department wasn't able to prove any such scenarios.

"Ultimately, we weren't able to make a determination of how it happened," she said.

Most of the corn and soybeans grown in the United States are already modified, or genetically altered, to resist certain herbicides. But the country's wheat crop is not, as many wheat farmers have shown reluctance to use genetically engineered seeds since their product is usually consumed directly by people. Much of the corn and soybean crop is used as feed for animals.

There has been little evidence to show that foods grown from engineered seeds are less safe than their conventional counterparts, but several states have considered laws that would require them to be labeled so consumers know what they are eating. Vermont became the first state to enact such a law this year.

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