(Aug. 2) It appears California’s fresh tomato grower-shippers may relax, at least temporarily, according to a researcher studying the tomato yellow leaf curl virus, which appears to have been isolated in a remote region of Southern California.

“We’re optimistic we may have dodged a bullet due to the early identification of the virus,” said Robert Gilbertson, plant pathology professor at the University of California-Davis, during a July 30 news conference in St. Paul, Minn.

The virus was discovered in a greenhouse on a high school campus in the Imperial Valley, Gilbertson said at a meeting of the American Phytopathological Society. It was the first discovery of the virus in California, he said.

“This is widely considered the most damaging virus of tomatoes in the world,” Gilbertson said.

Whiteflies carry the disease, and researchers suspect the insects carried the virus from Mexico to Brawley, Calif. There have been no outbreaks found in the valley’s commercial tomato fields.

“The DNA of the virus discovered in the greenhouse was an exact genetic match with the virus found in Mexico,” he said.

Gilbertson said the virus was discovered in some backyard gardens and in some weeds near the campus. The weeds are a particular concern, he said, because the virus is not fatal to host weeds. It’s impossible to spot the virus in weeds via visual inspection, he said.

Research is underway to determine how well the whitefly can pick up the virus from the weeds.

“That’s a big concern,” Gilbertson said. “Traditionally, it’s been impossible to eradicate the virus because it becomes established in the weeds.”

As Imperial County and California Department of Food and Agriculture officials continue to scour the Brawley area for the virus, apprehension persists among scientists and grower-shippers.

“We’re very worried about the movement of this virus into the San Joaquin Valley and its potential to devastate California tomato production,” Gilbertson said.

Gilbertson said whiteflies are very sensitive to cold climates and are unable to overwinter in the San Joaquin Valley, where a majority of the state’s tomatoes are grown.