The $35 billion U.S. organic-food industry has nearly tripled in size in the past decade, challenging the Agriculture Department’s ability to monitor the more than 25,000 farms and other organizations that sell organic crops and livestock.

There are currently 81 accredited “certifying agents,” or groups that stamp food as organic in the U.S. But of the 37 that had a complete review this year, 23 were cited for failing to correctly enforce certification requirements on farms in audits, according to an internal Agriculture Department report. The 23 firms didn’t properly conduct onsite inspections or correctly review applications for organic certification, among other things, the report said.

A separate Wall Street Journal investigation of USDA inspection records since 2005 found that 38 of the 81 certifying agents failed on at least one occasion to uphold basic Agriculture Department standards.

In that time, 40% of these 81 certifiers have been flagged by the USDA for conducting incomplete inspections; 16% of certifiers failed to cite organic farms’ potential use of banned pesticides and antibiotics; and 5% failed to prevent potential commingling of organic and nonorganic products, according to the Journal investigation.