Bad Armadillo Vineyard - Pierce's Disease

Pierce's disease (PD), a lethal disease of grapevine, is caused by the bacterium Xylella fastidiosa and is spread by certain kinds of leafhoppers known as sharpshooters. Pierce's disease is only known from North America through Central America and has been reported from some parts of northwestern South America. It is present in some California vineyards every year, with the most dramatic losses occuring in the Napa Valley and in parts of the San Joaquin Valley. During severe epidemics, losses to PD may require major replanting. In Florida and other southeastern states, PD has precluded commercial production of European varieties, but some muscadine grapes and hybrids of American wild grape species wtih European grapes (Vitis vinifera) are tolerant or resistant to PD.

Pierce's disease, named after N.B. Pierce, seems to be restricted to portions of North America with mild winters. The disease is less prevalent where winter temperatures are colder, such as at higher altitudes, farther inland from ocean influences, and at more northern latitudes. It has been found in all southern states that raise grapes commercially; from Florida to California, and in Mexico and Central America. In the southeastern states, from Florida through Texas, PD is the single most formidable obstacle to the growing of European-type (Vinifera) grapes. Since the mid-1970s, many other strains of Xylella fastidiosa have been discovered, and almost all of these cause leaf scorching of woody perennials such as American elm, maple, mulberry, or plum. In some plants, such as peach and alfalfa, the bacterium slows and stunts plant's growth.