Sharpshooter out of grapes, now grapevines in trouble

The war against California's worst ever grape pest, the glassy-winged sharpshooter (GWSS) and the Pierce's Disease (PD) it vectors, has had good news and bad news of late.

The good news is that state inspectors have checked more than 60,000 shipments of grapes so far this season-without finding a single sharpshooter.

Unfortunately, the same cannot be said of those who are checking the grapevines.

Pierce's Disease (PD) was recently discovered in a vineyard in southeast Kern County, off General Beale Road. Six grapevines tested positive for PD and were removed even though the grower had made multiple treatments to control GWSS populations of glassy-winged sharpshooter (GWSS). The Kern County Agricultural Commissioner is conducting extensive PD sampling in surrounding vineyards. This is the first time vines have been removed from San Joaquin Valley vineyards since the sharpshooter first appeared in the northern valley. It is widespread in Southern California.

The Kern/Tulare GWSS/PD Task Force is meeting with USDA, CDFA, University of California Cooperative Extension Service, and the Kern ag commissioner's staff to develop a coordinated approach to control GWSS and PD in the General Beale Road area.

And, inspectors continue to find sharpshooters in residential neighborhoods and in nurseries throughout the state.

In late September, Santa Ynez County inspectors found a single adult female sharpshooter in a trap placed in a Santa Ynez residential neighborhood located near vineyards. The trap had been placed by the Santa Barbara County Agricultural Commissioner's staff as part of an ongoing effort to track this pest, which had not previously been found in this part of the county.

A week early inspectors found single adult sharpshooters in nurseries in three counties, Stanislaus, Sacramento, and Sonoma. All nurseries were surveyed and treated.

University of California, Riverside entomologists have released parasitic wasps from Mexico in three locations statewide to help reduce GWSS populations.

One area was in Kern County citrus, not far from where the grapevines were taken out and sharpshooters were swarming all over citrus.

The same wasp species has been released in Temecula where the sharpshooter has caused major damage, and in Ventura where citrus is a major crop and a primary host for sharpshooter.

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