Invasive glassy-winged sharpshooter detected on plants sold at Northern California Costcos.

Agricultural inspectors have discovered a damaging and invasive pest known as the glassy-winged sharpshooter (GWSS) on grapevine shipments sold at select Costco locations across Northern California. 

The detection of the pest is concerning as it can damage citrus trees, landscape plants and crops, as well as spread a bacterium that causes Pierce’s disease, a fatal grapevine disease known to threaten California vineyards.

The California Department of Food and Agriculture’s Pierce’s Disease Control Program is working with Costco Wholesale and county agricultural officials to prevent the pest from spreading further. 

People who purchased a grapevine or fruit tree at Costco in Sand City or Salinas between April 21 and May 19 should contact the County of Monterey Agricultural Commissioner’s Office at (831) 759-7370. 

"We have gotten several telephone calls from the public in the last few days, and we have collected suspect specimens on a couple of inspections," says Agricultural Commissioner Juan Hidalgo. "These were sent to the CDFA state lab for analysis and so far, none has been found to be GWSS. GWSS is a pest not found in our county and we do yearly surveillance for it from spring until fall." 

The Agricultural Commissioner’s office also recommends that affected customers isolate the plant by keeping it in its original pot away from other plants, avoid putting the plant in the ground, place the plant in two trash bags and seal the bags.

People who believe they have a plant matching these details should not return or relocate the plant, and should not place the plant in the trash or compost bin.

Fresno County Agricultural Commissioner staff and CDFA personnel have been working onsite at Burchell Nursery since May 19 to stop shipments, investigate the situation and determine corrective actions.

Costco has reportedly been notifying customers, issuing refunds and helping connect purchasers with local county ag commissioners for inspection and disposal guidance.

Monterey County has received plant shipments, but inspections have not yet detected any glassy-winged sharpshooter.

The pest has been confirmed on plants shipped to Alameda, Marin, Placer, Sacramento, San Mateo, Solano, Stanislaus and Yolo counties. 

Officials are still evaluating additional suspect samples from several other counties, including Butte, Contra Costa, Humboldt, Merced, Napa and Sonoma counties.