Tomato Crop Faces Virus Peril : Agriculture: Disease carried by pest has affected much of the county’s yield and all of Irvine’s. A USDA official fears it could spread to other produce.

Orange County’s $17-million tomato industry is threatened by a new and “extremely serious” virus that has destroyed much of the county’s recent crop, officials from the U.S. Department of Agriculture said Thursday.

According to researchers, the disease is transmitted by a nutrient-sucking insect called the greenhouse whitefly and currently has “affected 100% of the (tomato) crops in the Irvine area.”

Last fall, growers in Irvine contacted the USDA after their crops started to fail.

James E. Duffus, a USDA plant pathologist, said preliminary information has shown that the new, previously unidentified virus can be devastating.

“This is one of the most destructive diseases for tomato crops occurring in the state,” Duffus said.

He said the new virus is similar to a virus that has caused severe damage to desert lettuce and sugar beet crops.

Duffus presented his findings Thursday at a conference of California produce growers in San Francisco. He told them he was concerned about the disease’s “potential to spread” to other tomato-farming regions throughout the state.

California is the nation’s No. 1 producer of tomatoes. In Orange County, they grow on more than 1,700 acres of farmland and are the third most valuable crop, behind flowers and strawberries but ahead of oranges.

Marcia Wood, a USDA spokeswoman, said the virus has already “induced severe crop losses” in Orange County. No other region seems to be affected by the new virus.

Duffus said that at least one Orange County farm has stopped growing tomatoes because of the disease.

“They’re afraid to start growing again,” Duffus said.

The financial toll the virus has caused in Orange County is not yet known, Duffus said. No local growers could be reached for comment Thursday night.

Duffus said the disease causes yellowing, decay and death of the plant. He said it is possible that the disease could infect other crops in the county.

“We’re looking into that,” he said.

Researchers also are studying ways to control the spread of the virus. Although pesticides might work, Duffus said he hopes to find an environmentally safe alternative.

If the virus is not controlled, it could “force the abandonment” of Irvine as a tomato-producing area, he said, adding that it could be several years before an “antiserum” is found to defeat the virus.

“At this point we just don’t know a whole heck of a lot about this virus,” Duffus said.

The most important thing right now, Duffus said, is to discover the source of the virus that the pest carries. Once the source is isolated, “than maybe we can eliminate it as a problem,” he said.