Ag Commissioner Update: Oriental Fruit Fly Detection

On Tuesday, August 6, 2024, an adult male Oriental Fruit Fly (Bactrocera dorsalis) was detected in a pest detection trap in Sonoma County, just outside the town of Sonoma. The trap, located in a fruit tree on a residential property near 8th Street East and Old Winery Road, caught the attention of the California Department of Food and Agriculture (CDFA) and local county agricultural departments. While the discovery of a single fly does not immediately trigger a quarantine, it does call for increased fruit fly trapping and monitoring, which in this case, extends into parts of Napa County.

In response to this finding, Sonoma County Ag, Napa County Ag, and CDFA are collaborating to place additional delimitation traps around the core area of the detection. Over the next week, 425-450 traps will be deployed within a 4.5-mile radius, covering parts of southwest Napa County, including areas around Redwood Road, Partrick Road, Mt. Veeder Road, and the western section of Carneros. CDFA staff began placing traps on August 9 and 10, primarily in residential and roadside host trees, with the goal of ensuring no further adult flies are found, thereby avoiding a quarantine. So far, CDFA has successfully treated the initial find site and adjacent properties in Sonoma County.

As of today, all delimitation traps have been successfully deployed around the find site, encompassing the core area (1 square mile), the first buffer zone (9 square miles), and the outer buffer zones (16-32 square miles). These traps have been checked and serviced multiple times. Initially, daily checks were conducted during the first week. With no additional findings, the frequency of servicing has been reduced to weekly, starting August 19. Currently, 222 traps are set in Sonoma County and 62 in Napa County. CDFA staff will continue their trapping activities throughout the delimitation process.

It’s important to note that last year saw an unprecedented number of exotic fruit fly detections and active quarantines in California. Fortunately, all seven fruit fly quarantines last season, including those in nearby counties like Sacramento, Contra Costa, and Santa Clara, successfully eradicated the pest populations, allowing the quarantines to be lifted. This serves as a reminder of the importance of ongoing pest exclusion and detection efforts to protect our agricultural communities.

Growers within the delimitation area in Napa have been notified, but it’s important to stress that there is currently no quarantine in place, so vineyard and winery operations can proceed as usual. We remain vigilant and committed to safeguarding our agricultural lands from invasive species and ensuring that Napa’s renowned wine industry remains unaffected by these potential threats. Stay tuned for further updates as we continue to monitor the situation closely.