In a letter last week to John Mackey, cofounder and co-CEO of Whole Foods, five organic farmers gave him — and the world — a piece of their minds regarding the company’s new “Responsibly Grown” ratings system. Whole Foods has long used scales, like their numerical 1-5 meat ratings, to help consumers find the sweet spot where ideal price point meets ethics. Within the “Responsibly Grown” program, produce is labeled either “conventional” or “organic,” with further categorization — “unrated,” “good,” “better” and “best” — doled out according to sustainable-farming practices but irrespective of certification.

Basically, the farmers told Mackey that with these ratings, his company is throwing them under the bus and undervaluing their work to produce organic food. A big part of that has to do with the expense — between $5,000 and $20,000 per farm — and paperwork that goes into participating in the Whole Foods system.

Not only did the farmers state that it is not cool to be paying these amounts — essentially a sort of required marketing fee just to have their produce in Whole Foods — but they also criticized the scheme itself. They wrote in the letter that “the ‘Responsibly Grown’ program allows conventional farmers utilizing lower-cost management techniques, still incorporating toxic inputs, to unfairly compete with Certified Organic produce in your stores on a level footing with — or even rated better than — organic farmers.”

The farmers point out, “Why would your customer buy a ‘good’ asparagus, from a local, Certified Organic farm, when they could spend a lot less to buy the ‘best’ asparagus from a conventional farm in Mexico?”

That organic farmers can stand up to Whole Foods in this way suggests that the U.S. food movement has reached a peak in terms of awareness about, and consumption of, organically produced foods. As the Organic Trade Association has reported, sales of certified organic products have increased dramatically in recent years, with sales up more than 11 percent last year — a big jump.

Co-ops, CSA programs and farmers’ markets have played a role in this increase, and together they pose a potential threat to Whole Foods’ image as a principal retailer of healthy, organic foods. But the number-one purveyor of organic foods in the U.S. is perhaps the most unlikely source: Costco. The Seattle Times reported recently that Costco’s sales of organic products exceeded $4 billion last year, whereas Whole Foods’ organic sales were $3.6 billion.

Nevertheless, even in this competitive climate, Whole Foods is still an industry leader. It is symbolically important as a large company that purports to be an agent in a healthy national food system, a company that is rapidly expanding in U.S. cities, with a new shop, 365, planned that will cater to less-affluent, eco-conscious millennial consumers.

The controversy raises some interesting questions not only about how far the U.S. has come in regards to improving its farming system, but also about which challenges exist on a large scale. Thanks to regular people and organizations building awareness about the benefits of growing and eating organic foods over the decades, large companies like Costco and Wal-Mart now understand that they must carry organic products to appeal to everyday consumers. But by moving into the mainstream, “organic” has become nuanced enough that Whole Foods feels the need to employ this new ratings system. How will the company respond to the farmers’ letter and their list of demands, one of which proposes that “No produce should ever be rated ‘better’ or ‘best’ in the program unless it is Certified Organic”?

Perhaps the company will rescind its ratings system or put a better one in place — one that helps consumers who want to eat well at a reasonable price — without asking farmers to shoulder an additional financial burden or devaluing the work they do to put organic food on the market.