What is Pierces Disease?
Pierce’s disease is a fatal bacterial disease of grapes. It is caused by the organism, Xylella fastidiosa. The bacterium blocks the xylem tissues of the plant. Xylem tissues are the water- and nutrient-conducting vessels of plants. The typical symptoms are for leaves on the plant to begin to dry or to scorch. Infected vines can die in as little as one to two years. Pierce’s disease has existed for more than 100 years in the state, but until the arrival of the GWSS, there really was not a “effective” vector capable of rapidly transmitting the bacteria from vine to vine throughout a vineyard. Pierce’s disease decimated 40,000 acres of grapes in the Anaheim, California area in the late 19th century. It was dubbed “Anaheim disease”, but the name was later changed in honor of Newton Pierce, who studied the infection. The incurable plant disease has appeared on and off ever since, but its spread and transmission has been limited. Until the arrival of GWSS, the principal carrier, or vector, o
