Wine Country warned about harmful grapevine pest found on Costco plants

NAPA COUNTY, Calif. - Agricultural officials from across Northern California are tracing potentially infected grapevines sold at local Costco stores after detecting a highly destructive pest.

Invasive Pest Threatens Vineyards

The multi-county alert centers on the glassy-winged sharpshooter, an invasive insect resembling a cricket. While the insect itself does not kill vegetation, it carries Pierce’s disease, an incurable bacterial infection that blocks a plant's water-conducting systems and dries it out, eventually killing the vine.

Between 1994 and 2000, the pest caused an estimated $30 million in damage in Northern California, according to a 2008 study from the University of California.  

"The insect isn’t the deadly part," said Rene Byck, co-owner of Paradise Ridge Winery outside Santa Rosa, who received an alert from the Sonoma County Department of Agriculture. "It’s the Pierce’s disease that it actually carries to the vines, and that’s the big concern, because eventually the vines will die."   

Tracking Infested Retail Plants

The state's agricultural tracking efforts traced the affected grapevines back to Burchell Nursery in Fresno County. From there, the plants were shipped and sold at Costco locations across Marin, Solano, Yolo, Sonoma, and Napa counties.

"I think we’re all very concerned and are doing our best to try to trace forward those plants," said Tracy Cleveland, Napa County’s Agricultural Commissioner.

In Napa County alone, 63 grapevines delivered to a Costco location, including one found with an insect egg mass on it, have been successfully intercepted and destroyed. However, 157 grapevines sold to the public between April 21 and Tuesday remain completely unaccounted for.

Costco is working closely with agricultural commissioners across the affected counties to identify the buyers and has begun directly contacting customers who purchased the plants.

Crucial Instructions for Consumers

Agricultural authorities are urging consumers who purchased grapevines from regional Costco stores over the past month to take immediate containment measures rather than handling the plants normally.

"If you purchased plants and they’re still in the container, don’t put them in the ground," Cleveland warned. "If you can secure those plants, put them into trash bags, two trash bags, double bag it and seal it, so it can contain anything that might be on it."

Officials explicitly noted that residents should not attempt to return the plants to their local Costco, move them, or place them loosely into household trash or community compost bins. Instead, anyone who believes they bought one of the targeted plants should immediately contact their county agricultural commissioner's office for proper handling.

Vineyard Owners Brace for Economic Fallout

Local vintners are closely monitoring the situation. For business owners like Byck, who is currently navigating shrinking market demands for wine, after recovering from the catastrophic losses during the Tubbs Fire, an outbreak could prove devestating to the business.

"There’s no cure, if your vineyard gets it, you’ll just get passed from vine to vine," said Byck.

Replacing an infected vineyard is a grueling process that takes years of cultivation and substantial capital.

"You got to pull them out which costs money, you got to buy the root stock which costs money, you got to regear the whole trellis system," said Byck. "And there’s no insurance that covers something like this."