(Aug. 9) A potato virus previously found only outside the U.S. has been discovered in Maine.

The mop top potato virus has been found in potatoes on one and possibly two farms in Maine, The Maine Potato Board, Presque Isle, said Aug. 8. The virus causes discoloration or rings inside potatoes and renders them unusable for the fresh and processed markets.

The good news, said Anna Cherry, a spokeswoman for The U.S. Department of Agriculture’s Animal & Plant Health Inspection Service, is that the virus cannot be passed through the air — so is easy to contain — and that it does not pose a health risk.

“It’s always the best thing in these cases to hear that the virus is not airborne,” Cherry said.

Cherry said Aug. 9 that an APHIS team was in Maine working with the Maine Department of Agriculture on a plan for dealing with the virus. For now, she said, investigators are looking only at the two farms in question. Additional farms in Maine and in other states could be inspected. Under USDA guidelines, fields found with the virus must be quarantined.

Because this is the first time mop top has been found in the U.S., APHIS investigators are taking their time before deciding how to proceed, Cherry said. Mop top virus has been found previously in Canada, Europe, Asia, and South and Central America.

A 2001 report by the Swedish University of Agricultural Sciences reported that mop top had been found in all Scandinavian countries during the 1990s and had been “very damaging” for some crops, producing substantial losses for growers. The report also said that mop top can remain in the ground for at least a decade.