Author: David Aguayo, Asst. Agricultural Commissioner / Sealer
Date: 6/4/2026 4:07 PM

County agricultural inspectors have completed an investigation into a recent statewide nursery shipment incident involving the Glassy-Winged Sharpshooter (GWSS). Ongoing inspection and trapping efforts continue to protect local agriculture and nursery industries.

The San Luis Obispo County Department of Agriculture/Weights and Measures has completed its local investigation into a recent statewide nursery shipment incident involving the Glassy-Winged Sharpshooter (GWSS), an invasive agricultural pest capable of transmitting Pierce's Disease to grapevines. While GWSS poses no risk to human health, it is a California-rated pest of significant concern to the state's grape industry.

Between April 21 and May 21, 2026, a wholesale nursery in Fresno County shipped grape plants containing viable GWSS life stages to several retail locations throughout California. After being notified of the incident, San Luis Obispo County agricultural officials immediately initiated an investigation to determine whether any potentially affected plant material had been distributed locally.

The investigation confirmed that while the Fresno County nursery did ship plants to the San Luis Obispo Costco during the relevant period, none of the shipments included grape plants or any detectable life stages of GWSS. Collaboration between County agricultural officials and Costco representatives was instrumental in ensuring timely access to shipping records and plant materials for inspection.

"The coordination and cooperation demonstrated among county agricultural commissioners, the California Department of Food and Agriculture, Costco representatives, and the public in responding to this issue statewide has been commendable," said San Luis Obispo County Agricultural Commissioner, Martin Settevendemie. "Together, we will continue working to mitigate any potential risks posed by this situation."

Out of an abundance of caution, County agricultural staff conducted comprehensive visual inspections of all plant material at the San Luis Obispo Costco location. Inspectors examined plants for GWSS eggs, nymphs, and adults and found no evidence of the pest. In addition, insect detection traps were deployed on the property and throughout the surrounding shopping center to support ongoing monitoring efforts.

Based on the County's investigation, the risk to San Luis Obispo County from this statewide incident is considered extremely low. Nevertheless, protecting local agriculture remains a top priority, and monitoring efforts will continue. The Department maintains robust inspection and detection programs to prevent the introduction and spread of agricultural pests and diseases. San Luis Obispo County remains classified as non-infested for GWSS.