Two national advocacy groups are suing a Sioux City cooperative they say is falsely advertising its honey as pure, despite tests that show it contains traces of glyphosate, used in Roundup, the most widely used farm herbicide in the world.

The Organic Consumers Association and Beyond Pesticides claim that Sioux Honey Association, the 95-year-old cooperative that makes Sue Bee Honey, is misleading consumers by labeling its honey as pure and natural.

The advocacy groups say their lawsuit is more than a labeling dispute — it's an attempt to push retailers and, ultimately, federal agencies to adopt better standards and practices that would protect bees, honey and consumers from contamination from herbicides that are widely applied by farmers.

The lawsuit points to U.S. Food and Drug Administration documents that indicate Sue Bee Honey contains traces of glyphosate, the active ingredient in Roundup. It also highlights a gap in government oversight over the herbicide, which experts say is inadvertently getting into honey.

While the herbicide residue "may be due to the application of glyphosate on crops by neighboring farms and unrelated to beekeeping activities," the advocacy groups say "labeling and advertising of Sue Bee products as 'Pure,' '100% Pure,' 'Natural,' and 'All-Natural' is false, misleading and deceptive."

Sioux Honey Association, with 300 members nationally, didn't respond to requests for comment on the lawsuit and testing.