(UDPATED COVERAGE, Aug. 22) South Korea has banned imports of potatoes from Oregon, Washington and Idaho over fears of zebra chip disease.

The ban went into effect Aug. 17, said Bill Brewer, executive director of the Portland-based Oregon Potato Commission. It covers fresh potatoes and chipping potatoes, said Matt Harris, trade director for the Moses Lake-based Washington State Potato Commission.

Oregon growers could be the ones hardest-hit.

“We ship quite a bit, Washington a fair amount and Idaho a little,” Brewer said.

The majority of Oregon, Washington and Idaho potatoes shipped to South Korea are for processing, Brewer said. In 2011, about 16,700 metric tons of fresh-market U.S. potatoes, worth about $6 million, were shipped to South Korea, according to the U.S. Department of Agriculture’s Foreign Agricultural Service.

The ban came as a “little bit of a shock,” Brewer said. Zebra chip, which affects quality but doesn’t pose a risk to humans, is spread by psyllids, and sprout-inhibition treatments Oregon potatoes receive prior to shipment should erase any risk of zebra chip contamination, Brewer said.

“We don’t think (the ban) is justified, because of scientific reasons,” he said. “The probability of something getting there is very slim.”

Brewer added that none of the scientific data received from South Korea’s equivalent of the USDA’s Animal and Plant Health Inspection Service indicates the presence of psyllids in South Korea.

The issue could come up at trade talks scheduled for later this month between USDA and South Korea, Brewer said.

Harris said the U.S. potato industry is working with APHIS officials on short- and long-term solutions to address the ban. Washington growers shipped about 7,000 tons of potatoes to Korea last year, most of it for chipping, he said.

Because of an earlier ban for pale cyst nematodes, fresh potato exports from Idaho to South Korea have been very limited in recent years, said Frank Muir, president and chief executive officer of the Eagle-based Idaho Potato Commission.

“We were only getting back into the market,” Muir said.

Muir is confident that once APHIS officials meet with their South Korean counterparts and discuss how zebra chip is contracted through psyllids and not from the potatoes themselves, the ban will eventually be lifted.

“But we respect the Koreans’ right to ask the questions to ensure they are not at risk,” he said.