Agricultural officials in San Luis Obispo County launched an investigation after learning that a Fresno County wholesale nursery shipped grape plants containing viable glassy-winged sharpshooter life stages to Costco locations across California between April 21 and May 21.
Paul Clark, Executive Director of the San Luis Obispo County Farm Bureau, explained why the pest poses a significant threat to the wine and grape industry.
"It spreads a disease called Pierce's disease," Clark said. "It essentially kills the grapevine by preventing the water from passing through the xylem, making the plant dry up and die."
The contaminated plants were distributed to 23 counties:
- Alameda, Butte, Contra Costa, Humboldt, Kings, Marin, Mendocino, Merced, Monterey, Napa, Placer, Sacramento, San Joaquin, San Mateo, Santa Clara, Santa Cruz, Shasta, Solano, Sonoma, Stanislaus, Tulare, Yolo and Yuba
David Aguayo, Assistant to the Agricultural Commissioner, said officials determined that while the Fresno nursery did ship plants to the San Luis Obispo Costco, none of those shipments included grape plants or any detectable life stages of the sharpshooter.
A link to the investigation can be found HERE.
"From there, we went in and inspected the necessary product that was received not only from that particular nursery, but what they had in stock as well, just in case anything was co-mingled," Aguayo said.
As a precautionary measure, county agricultural staff placed insect detection traps on the Costco property and throughout the shopping center.
Clark emphasized the importance of vigilance in preventing the spread of invasive species, particularly through casual plant purchases.
"On a commercial scale with vineyards, with nurseries, everyone is pretty aware," Clark said. "But when it's a casual transaction, bringing plants from other counties or other states, you have the potential to spread species that could cause a lot of damage to our agricultural economy."
County officials are asking residents who purchased grapevines outside San Luis Obispo County and brought them into the region to contact the agricultural commissioner's office.
