Organic fruits and vegetables accounted for less than 5% and 10%, respectively, of the fruits and vegetables sold to U.S. consumers last year, but as their popularity continues to steadily increase, the U.S. Department of Agriculture is stepping up labeling enforcement.

In mid-August, the USDA’s National Organic Program issued an “instruction” on the use of brand and company names containing the word organic. Anyone who knowingly sells or labels a product as organic that does not meet the statutory definition can be fined up to $10,000 and be banned from organic certification for up to five years.

“The policy clarification is needed to provide fairness and equity in label use throughout the organic industry and to satisfy consumer expectations for organic products,” according to a statement from program officials.

Statistics compiled for United Fresh Produce Association by the Nielsen Perishables Group showed sales of organic produce increased in both volume and dollar sales in 2013. The United Fresh FreshFacts on Retail report showed organic vegetables accounted for 8.6% of total fresh vegetable sales with average weekly dollar sales up 18.2% compared to 2012.

Organic fruits were less popular, accounting for only 4.4% of total fresh fruit sales in 2013. However, those sales were up 17.8% on a volume basis and 22.1% on a dollar basis, according to the United Fresh report.

At least one industry watchdog group praised the USDA for increasing enforcement efforts.

Mark Kastel, co-director of the Cornucopia Institute, Cornucopia, Wisc., said some companies have made it standard practice to mislead consumers by using the word organic in their trade names.