WEDNESDAY, MAY 27, 2026. BY SAN JOAQUIN CO. AG COMMISSIONER’S OFFICE.
Stockton, CA – The San Joaquin County Agricultural Commissioner’s Office is urging residents to take immediate precautions after the invasive glassy-winged sharpshooter (GWSS, pictured above right) was discovered on grape plants sold at Costco stores throughout the wider Northern California Region including the Central Valley. The Costco stores in Stockton, Lodi, Manteca, and Tracy are among those that received these grape plants from a wholesale nursery located in Fresno County.
The insect, a type of leafhopper, spreads Pierce’s disease, a plant bacterium that kills grapevines and can also harm almond, citrus and ornamental plants, creating a serious risk for California agriculture and home gardens. The pest threatens the state’s grape industry and is known to feed on more than 250 plant species, damaging vineyards and ornamental landscapes alike.
A plant tag for an “Autumn Royal” grape vine from Burchell Nursery, a variety of seedless purple table grape.
Anyone who purchased grapevines, citrus trees, or fruit trees from Central Valley Costco locations on or after April 21 should contact their county agricultural office to help stop the pest from spreading further.
The GWSS poses a significant threat to a wide range of agricultural commodities, making the prevention of further spread critically important. The San Joaquin County Agricultural Commissioner’s Office is working closely with Costco Wholesale, along with our state and local partners, to identify affected plants and protect agriculture, home gardens, and landscapes. The food supply remains unaffected. Costco has been cooperative and responsive throughout this process and is not responsible for the discovery, as the issue originated at the nursery supplier level.
What To Do If You Purchased a Plant
If you purchased a grapevine, citrus tree, or fruit tree from Costco in an affected county between April 21 and May 19, take the following steps:
1. Isolate the plant:
– Keep the plant in its original pot or container and away from other plants.
– Do not put the plant in the ground if you have not already done so.
– If possible, place the plant(s) in two trash bags, one inside the other, and seal them closed.
– Do not return, transport or relocate the plant.
– Do not place the plant in the trash or compost bin.
2. Contact the San Joaquin County Agricultural Commissioner’s Office at 209-953-6000 or StocktonAg2@sjgov.org to arrange an inspection.
– An agricultural inspector will come to look at the plant and other nearby host plants.
– If inspectors find GWSS on the grapevine, they will safely remove and dispose of the plant.
– GWSS monitoring traps may be placed on the property.
For more information, visit the California Department of Food and Agriculture.
A glassy-winged sharpshooter fact sheet from Contra Costa Co. can be found HERE and a bilingual fact sheet on the pest from Napa Co. is linked HERE.
Contact: San Joaquin County Agricultural Commissioner Office
StocktonAg2@sjgov.org, (209) 953-6000
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