A vine showing symptoms
of Pierce's Disease.
Pierce’s disease in grapevines was first noted in California near Anaheim around 1884. The disease is caused by a strain of the bacterium Xylella fastidiosa. It kills grapevines by clogging their water-conducting vessels (xylem). Several strains of this bacterium exist, attacking and causing damage to different host plants including grapes, citrus, stone fruits, almonds, oleander, and certain shade trees such as oaks, elms, maples, and sycamores. Since its discovery, Pierce’s disease has been reported and is known to exist in 28 counties (map of counties with PD). The University of California reported that the disease destroyed over 1,000 acres of grapevines in northern California between 1994 and 2000, causing $30 million in damages. There is currently no known cure for Pierce’s disease.Pierce's Disease Photo Gallery