(May 6) FRESNO, Calif. — California agriculture officials are frantically trying to find the cause of and solution to a plant fungus that recently prompted South Korea to indefinitely halt the import of oranges from two of California’s largest citrus-producing counties.

They’re frantic because South Korea is one of California’s top citrus export markets and the counties in question — Tulare and Fresno — represent about 45% of all oranges grown in the state.

Inspectors in South Korea discovered the fungus septoria citri on some fruit recently shipped from California.

The ban, announced April 27, does not affect oranges from other California counties, including Kern, which is the state’s second-largest producer.

Bob Blakely, director of grower services at California Citrus Mutual, Exeter, said the fungus forms spots on orange rinds but does not affect the inside of the fruit. Blakely also said the fungus is periodically found on oranges in the U.S.

He said May 6 that inspectors from the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service and the California Department of Food and Agriculture were examining fruit that had been returned from South Korea.

“They’re trying to get a handle on what the Koreans are looking at, from some of the fruit that was rejected,” Blakely said, adding that initial samples showed no signs of infestation but that analysis was continuing.

In 2003, South Korea imported about 123,000 metric tons of fresh oranges from the two counties — about 84% of its total orange imports and about 87% of oranges shipped from the U.S., Blakely said. Thus far in 2004, about 110,000 metric tons of fruit from the counties has been shipped into South Korea, or about 91% of its total imports.

Blakely added that the fungus is brought on by weather conditions and is not uncommon.

“It’s something that’s pretty much around in most citrus growing areas,” he said. “They don’t have it in Korea, though, so it is a quarantined pest. If they’ve found and verified it, and science is on their side, we have to find a way to mitigate it and make sure fruit isn’t infected with it.”

The bright side, Blakely said, is that the navel season is over and that the valencia season, which is a relatively minor part — about 20% — of the counties’ export business with South Korea, is getting under way.

Blakely estimated that the number of shipments rejected was “on the order of 20.”

Gary Kunkel, Tulare County’s agricultural commissioner, said South Korea was the county’s top export destination last year.

Last year, oranges accounted for 48% of its fruit and nut commodity exports, he added.