Pierce’s Disease Control Program / Glassy-Winged Sharpshooter Program

The Pierce’s Disease Control Program is primarily funded through a contract with the California Department of Food and Agriculture (CDFA), made possible by an assessment paid by grape growers. This program is a clear example of industry-funded efforts due to the direct benefits to the growers. Pierce’s Disease, caused by the bacterium Xylella fastidiosa, is spread by the Glassy-Winged Sharpshooter (GWSS), an insect that feeds on plant juices, particularly grapevines. The disease can severely damage vines, reduce yields, and, in severe cases, necessitate replanting.

Our department plays a key role in this program by inspecting all nursery stock shipments destined for restricted areas, ensuring 100% compliance with quarantine requirements. Crews from the department inspect over 75,000 individual plants monthly during peak periods to prevent the spread of GWSS.

The department also collaborates with CDFA, other California Agricultural Commissioners’ offices, and research institutions to further understand better pest control strategies and management. These efforts include conducting surveys, enforcing quarantine regulations, and educating stakeholders about GWSS and Pierce’s Disease. Through this integrated approach, significant progress has been made in controlling GWSS and reducing the impact of Pierce’s Disease. Ongoing research continues to build a foundation for long-term solutions to protect the region’s vineyards and grape industry.