Insect Pest Fails to Reach Wine Country, State Says

State officials believe they have stopped the devastating glassy-winged sharpshooter short of the Northern California grape-growing region that is the heart of the state’s wine industry.

Two years into the state’s protracted battle against the pest, a new report to the Legislature from state agriculture Secretary William J. Lyons Jr. said that despite new infestations in the last year, the $38-million battle is going better than most had hoped.

In Northern California, the bug has been found only in isolated places, none of them agricultural, Lyons said. Authorities also think that they have successfully clamped down on the major route by which the bug has been spreading since its discovery in Southern California in 1999: unregulated shipments of nursery plants.

The eradication effort “has brought considerable resources and expertise to bear against the glassy-winged sharpshooter and the disease-carrying bacteria it spreads, and we’ve achieved marked success,” said Lyons in a statement.

With wide areas of Southern California still infested, however, officials said the battle will be a long one. “We’re only about two years into a project that will probably take five to 10 years,” said Jay Van Rein, a spokesman for the California Department of Food and Agriculture. “But we’ve already done better than anyone expected us to do.”

Despite the optimistic tone of the report, some officials are declining to declare victory.

“I don’t feel content, because this has been working its way north,” said Assemblywoman Patricia Wiggins (D-Santa Rosa). “It’s good news for Northern California that [the sharpshooter] hasn’t taken hold here. That doesn’t mean it’s not coming.”

Unlike other pests that feed on fruit, the sharpshooter does its damage by delivering a bacterium called Xylella fastidiosa that it carries in its mouth. The bacterium causes Pierce’s disease, which clogs the water-carrying vessels in the plant, starving it of nutrients. Though Pierce’s disease has been around for more than a century in California farm country, the arrival of the aggressive, fast-moving glassy-winged sharpshooter from Mexico in 1994 supercharged its spread.

The sharpshooter has been found throughout Southern California, with satellite infestations in Butte, Contra Costa, Fresno, Sacramento, Santa Clara and Tulare counties. The worst damage has occurred in Temecula, where 1,000 acres of wine grapes have been destroyed, costing growers $40 million.

The only other large infestation in a farming region was in Kern County, where the pest has invaded a 13,000-acre area at the base of the Tehachapi Mountains. Farmers there have been pulling out infected vines, using repellents and releasing wasps that eat sharpshooter eggs.

Because grapes are a $438-million business in Kern County, this infestation has served as a kind of “huge laboratory” to test eradication procedures.

It is believed the pest spread north at least partly by hitchhiking on ornamental plants shipped from Southern California nurseries. In 2000, outbreaks were found in residential areas of Fresno, Chico, Rancho Cordova and San Jose. As local officials battled those, the state ordered a pervasive inspection program to check plants at their shipping and destination points.