By MITCH LIES
Capital Press
The South Korean government will shut off all shipments of fresh potatoes from Oregon, Washington and Idaho beginning Aug. 17 because of concerns over the presence of zebra chip in Pacific Northwest potatoes.
The disease, which was found for the first time in the Northwest last year, has been found in one field in Oregon and four fields in Idaho this summer.
The announcement, which came to the attention of the Oregon Department of Agriculture Aug. 10, threatens to undermine a significant market for Northwest potato growers.
Oregon growers shipped just under 12,000 tons to Korea last year and more than 17,000 tons in 2010.
The majority are used to make potato chips.
“We have producers in the Klamath Basin who produce based on contracts and who may not have a home for their potatoes,”  said Jim Cramer, administrator of the department’s commodity inspection division.
Cramer said the department will work with federal officials and officials from Idaho and Washington to try and get the export ban lifted.
One approach under consideration is to develop a paper explaining why the presence of zebra chip on Northwest potatoes poses virtually no risk to the Korean potato industry.
“It is a quality issue,” Cramer said, “but it is not a phytosanitary issue.”
“All these potatoes are washed first and they are never going to see the light of day other than a chip plant,” said Phil Hamm, an Oregon State University Extension plant pathologist. “I’m not sure why South Korea would be concerned if they’re only bringing them in for processing.”
Zebra chip reduces yields and produces bands in tubers that darken when fried, making potatoes infected with the disease unmarketable.
The disease is vectored by the potato psyllid and is not believed to spread from tuber to tuber.
Potatoes infected with the disease are unlikely to sprout, according to research. In the unlikely event an infected tuber was planted and sprouted, it would require a potato psyllid to feed on the infected plant before it would be at risk of spreading, Hamm said.
“It is very, very, very unlikely to be an issue,” Hamm said.
Zebra chip was first recorded in Mexico in 1994 and first observed in the U.S. in Texas in 2000.