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WASHINGTON (AP) — The Agriculture Department says unregulated genetically modified wheat has popped up in a second location in the U.S., this time in Montana.

According to NPR, the wheat was found when workers attempted to clear a field using weedkiller, and some of the plants would not die. It was because of a gene inserted into the plants that gives them a tolerance to an ingredient in the weedkiller.

No genetically engineered wheat has been approved for U.S. farming. Unapproved genetically modified plants pose a potential threat to U.S. trade with countries that have concerns about genetically modified foods.

USDA said Friday that the Montana wheat covered a much smaller area than a similar discovery in Oregon last year. And the wheat was found in a location where agricultural giant Monsanto legally tested such seeds 11 years ago. The plants in Oregon were found in a field that had never conducted such tests.

USDA has said the wheat would be safe to eat if consumed but that none of it ever entered commerce.

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