Pests and Diseases


Agricultural Commissioner Sealer of Weights and Measures

Greg Clark, Agricultural Commissioner Sealer of Weights and Measures

Pests and Diseases 

Napa County Pest Updates:

Napa County’s mild climate and agricultural history make it home to many pests and diseases, and we are constantly concerned about the introduction of new, exotic and destructive organisms. A significant exotic pest infestation could affect everyone in the county, through the loss of markets for farm products, increased pesticide usage and production costs, and higher food prices for consumers. 

Many of the pests we deal with are considered "native"—meaning they are either endemic in Napa County or have become so well established in the area that pest management - not total eradication - is the only option. A Web site maintained by the University of California provides excellent, up-to-date information for the identification and management of many common pests, such as ants, yellow jackets, moles, scale and powdery mildew. If you find an insect pest or disease that you are unable to identify as one of our native pests, please bring it in to our office in Napa where we can identify it for you and determine if it is beneficial or destructive, and native or exotic. 

To help prevent the introduction of exotic pests and diseases, the Napa County Agricultural Commissioner’s Office cooperates with the California Department of Food and Agriculture to enforce quarantine regulations, conduct detection surveys and maintain an insect trapping program. The movement of fruits, vegetables and landscape materials is rigorously monitored through our plant shipment inspection program. Countywide surveys for noxious weeds and other pests often result in efforts to contain or eradicate infestations. Our insect trapping programs routinely monitor for exotic fruit flies, Gypsy Moth, Japanese Beetle, and Western Grapeleaf Skeletonizer

In recent years, several new pests and diseases have threatened our economy and the appearance of our beautiful region. In 2000, an intense exclusion program was instituted to thwart the introduction of Glassy-winged Sharpshooter into this county. Following that threat, discoveries of Olive Fruit Fly in 2001 and Vine Mealybug in 2002 have raised an alarm with growers, and the 2000 confirmation of Sudden Oak Death and its spread across the county have raised concern about the future of our woodlands and landscapes.