Citrus disease find in California a mystery

Detections of sweet orange scab that began in California"s Imperial County groves have the citrus industry searching for an explanation - and a remedy.

The initial findings were in October in Bard, Calif. Subsequent discoveries included sites in Winterhaven, also in Imperial; and two other counties.

The fungus, which mars fruit appearance but not taste, turned up as well in inspections and tests at Blythe, Riverside County; and California State Polytechnic University, Pomona, in Los Angeles County.

"We were very surprised by the findings in Imperial County, and shocked about the findings at the campus of Cal Poly Pomona," said Joel Nelsen, president of Exeter-based California Citrus Mutual. "We"re trying to figure out what the sources of those infections are and how best to address it. Do we need a countywide quarantine? Do we need a smaller restricted quarantine area?"

Rind lesions that could render fruit unmarketable even when quality is otherwise intact are a big deal for California growers who send comparatively little citrus to the process market.

"Sweet orange scab is more critical to us than it is to our friends in Florida, because we"re not juice oriented," Nelsen said. "We"re fresh oriented and anything that impacts our fresh utilization is bad."

The biggest effect is likely to be in Imperial County.

"It"s just not a good situation in Winterhaven because we"ve got a lot of fruit there between lemons and oranges," Nelsen said. "Most of that fruit gets packed in other locales. So we"ve got to set up the right process and ensure we"re not spreading the windborne virus."