Epidemiological studies on grapevine Pierce's disease (Xylella fastidiosa) in California, US
Strains of Xylella fastidiosa (EPPO A1 quarantine pest) causing grapevine Pierce's disease can infect numerous other plant species without necessarily causing disease. However, these plant species could play an important role in the epidemiology of the disease. In coastal California (US), it has been observed that the incidence of grapevine Pierce's disease is constantly highest along the margins of vineyards adjacent to riparian habitats which harbour overwintering populations of insect vectors, in particular Graphocephala atropunctata. Previous studies have already showed that plants such as Artemisia douglasiana, Echinochloa crusgalli and Rubus procerus could carry bacterial populations. A list of perennial plants on which Graphocephala atropunctata was found, and which are commonly occurring in riparian habitats in California was compiled. These plants were inoculated in the field (mechanical inoculation) or in the laboratory (using infective G. atropunctata). Results showed that populations of X. fastidiosa were highest in most plant species within 3 to 6 weeks after inoculation and decreased over the next 3 to 4 months. It was found that the following plant species could support systemic populations of X. fastidiosa which survived throughout the year: Acer macrophyllum, Aesculus californica, Rubus ursinus, Quercus agrifolia, Sambucus mexicana, Genista monspessulana, Vinca major, Quercus lobata and Vitis rupestris.
Sources
Purcell, A.H.; Saunders, S.R. (1999) Fate of Pierce's disease strains of Xylella fastidiosa in common riparian plants in California.
Plant Disease, 83(9), 825-830.