The U.S. Department of Agriculture has confirmed the discovery of unapproved, genetically modified (GM) wheat plants growing in an un-planted agricultural field in Washington state. 

There was no evidence the wheat had entered the food supply, the USDA’s Animal and Plant Health Inspection Service said in a statement on Friday. The wheat is resistant to glyphosate, a widely used herbicide commonly referred to as Roundup. 

“USDA is collaborating with our state, industry and trading partners, and we are committed to providing all our partners with timely and transparent information about our findings,” the statement said. 

There are currently no commercially approved genetically modified wheat varieties, and incidences of rogue plants are rare. However, unapproved plants were found in 2018 in Alberta, Canada, in 2016 in Washington state, in 2014 in Montana and in 2013 in Oregon.

A Bayer Crop Science spokeswoman said the latest finding may have occurred on the site of a former field trial. Last year Bayer bought Monsanto, which in the late 1990s and early 2000s developed wheat genetically modified to withstand its Roundup herbicide, a weed killer containing glyphosate.