Xylella fastidiosa, a bacterium in the class Gammaproteobacteria, is an important plant pathogen that causes phoney peach disease in the southern United States, oleander leaf scorch, and Pierce's disease, and citrus variegated chlorosis disease (CVC) in Brazil.

Pierce's disease was discovered in 1892 by Newton B. Pierce (1856–1916; California's first professional plant pathologist) on grapes in California near Anaheim. It became a real threat to California's wine industry and overall economy when the glassy-winged sharpshooter (its vector), native to the southeast United States, was discovered in the Temecula Valley in California in 1996. It triggered a unique effort from growers, administrators, policy makers and researchers to work together in finding a solution for this immense threat. No cure has yet been found, but the understanding of Xylella fastidiosa and glassy-winged sharpshooter biology have exponentially increased since 2000, when the California Department of Food and Agriculture, in collaboration with different universities, such as University of California, Davis; University of California, Berkeley, and University of California, Riverside, and University of Houston-Downtown started to focus their research on this pest. The research explores the different aspects of the disease propagation from the vector to the host plant and within the host plant, to the impact of the disease on California's economy. All researchers working on Pierce's disease meet annually in San Diego in mid-December to discuss the progress in their field. All proceedings from this symposium can be found on the Pierce's disease website, developed and managed by the Public Intellectual Property Resource for Agriculture (PIPRA).