Xylella fastidiosa, a bacterium in the class Gammaproteobacteria, is an important plant pathogen that causes phoney peach disease in the southern United States, bacterial leaf scorch, oleander leaf scorch, and Pierce's disease (in grapevines), and citrus variegated chlorosis disease (CVC) in Brazil. In Europe it has attacked olive trees in the Salento area of Southern Italy causing the Olive Quick Decline Syndrome (OQDS).