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Disease-Carrying Vineyard Pest Reappears in Sonoma

Lynn Alley
Posted: June 14, 2000

For the second time in less than 30 days, eggs of the glassy-winged sharpshooter -- an insect that carries Pierce's disease, a devastating grapevine malady -- were found in Sonoma County, one of California's top wine regions.

Two egg masses, one of which was viable, were found by an agricultural inspector on a shipment of ornamental plants to Neon Palm Nursery in Santa Rosa on June 7. The entire shipment was returned to its point of origin at a wholesale nursery in southern California's Ventura County. The first sighting of the bug in Sonoma was at a Home Depot in Rohnert Park, just south of Santa Rosa, on May 15.

The new sightings of the insect have heightened fears among agricultural officials, grapegrowers and winemakers about the devastation that Pierce's disease, which has no cure, could wreak on North and Central Coast viticultural regions. The glassy-winged sharpshooter carries the Xyllela fastidiosa bacteria, which chokes off a vine's water-carrying tissues, eventually killing it.

"We now have 700 traps in place throughout the county, with six full-time agricultural inspectors canvassing the county's nurseries, looking for signs of the glassy-winged sharpshooter," said Joseph Gray, senior agricultural biologist at the Sonoma County Agricultural Commissioner's office.

The glassy-winged sharpshooter has also been sighted recently in Alameda County, in the Livermore Valley wine region. There, two egg masses and seven nymphs, or juvenile sharpshooters, were discovered in a nursery in Sunol on May 16, and an adult was found in a nearby vineyard, about a quarter of a mile away from the nursery, on June 1.

Also in May and early June, a total of six adult glassy-winged sharpshooters were found in or near nurseries in Lodi, a Central Valley wine appellation.

In recent weeks, the number of counties officially designated as "infested" by the California Department of Food and Agriculture has jumped from eight to 10. Fresno and Tulare counties -- both in the Central Valley wine region -- joined the list of eight southern California counties (Santa Barbara, Riverside, San Diego, Orange, Los Angeles, Kern, San Bernardino and Ventura) that were first hit by the pest. The CDFA defines an "infested" county as one in which five live adult sharpshooters have been found outside of a nursery setting.

To help deal with the growing problem, CDFA Secretary Bill Lyons Jr. has formed a new scientific advisory panel, made up of six of the country's most prominent researchers in the field of Pierce's disease and sharpshooter management. The panel will initially work in Tulare County, where an entire colony of glassy-winged sharpshooters was recently discovered.

Also joining the battle against the sharpshooters are 50 members of the California Conservation Corp., which is made up of people between the ages of 18 and 23 years who perform service-oriented conservation work around the state for minimum wage. CCC members have been taught by CDFA personnel how to identify the bug, and they are currently involved in door-to-door canvassing and field work in Tulare, Fresno and Madera Counties.

# # #

  • May 18, 2000
    Vineyard Pest Established in California's Central Valley

  • May 16, 2000
    Deadly Vineyard Pest Reaches Sonoma County

  • May 11, 2000
    Vine-Killing Pest Found Near California's Lodi Wine Region

  • April 4, 2000
    As Deadly Vine Disease Spreads, California Promises Funds to Fight It

  • Feb. 25, 2000
    Deadly Vine Disease in California Draws Congressional Attention

  • Feb. 14, 2000
    California Growers Battle Carrier of Pierce's Disease

  • Oct. 13, 1999
    New Pierce's Disease Carrier Spreads to Lodi

  • Sept. 16, 1999
    Pierce's Disease Devastates Vineyards in California's Temecula Region

  • May 14, 1998
    An Old Pest Poses a New Threat to California Vineyards

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