An almond milk startup says oat milk is too problematic to add to its lineup for now. New Barn Organics, a California-based almond milk producer, says it’s not rushing into making beverages from oats until a cleaner supply is available.

Oat milk is all the rage these days among fancy coffee-shop frequenters – for its froth-ability and as part of the trend toward plant-based foods. But it faces environmental issues, according to Ted Robb, chief executive officer of New Barn, the startup backed by former Whole Foods Market Inc. Co-CEO Walter Robb, who’s also on the company’s board.

Most oats are “bathed in glyphosate”, Ted, Walter’s son, said in a recent internal memo to company employees. The memo referenced Roundup, the world’s No. 1 weedkiller, whose active ingredient is glyphosate. He also said oats create “very little value” for farmers.

“I’m not opposed to making an oat milk some day, but it needs to be done right,” he said.

That includes regenerative organic oats, grown in the US as a cover crop, and transparency through the supply chain, Robb said. Bloomberg DM