The aim of this project is to evaluate the fate of the Pierce’s disease (PD) bacterium (Xylella fastidiosa) in various plant species to enable vegetation management for control of PD. Plant species that are preferred hosts of PD vectors are being tested first, but we are also screening plants to identify plants that are not hosts and thus are potential replacements for plants that are good hosts of the bacterium. Of 4 woody perennials inoculated with PD bacteria in late summer, 1994, we detected survival and multiplication of the bacterium in live oak and maple but not in spice bush or bay laurel. Survival over the last winter will be estimated in late summer, 1995. There was some indication of systemic movement of bacteria in maple; further tests are underway in greenhouse and field trials. The bacterium multiplied and spread in French broom, was transmitted from broom to grape in insect vector trials, and was recovered from naturally-infected broom near vineyards. Multiplication without systemic (within-plant) spread was detected in coyote brush, elderberry (more tests needed to evaluate spread), ivy, and mugwort. No bacterial multiplication was detected in 8 additional plant species evaluated in the lab. Fifteen perennial plant species located in riparian vegetation along a stream in Napa Valley were mechanically inoculated (40-60 sites for each species) with X. fastidiosa in April-May, 1995 and will be tested in late summer for bacterial multiplication, within-plant movement, and overwinter survival. Greenhouse-grown seedlings of these and other plant species were inoculated in the lab with infective sharpshooters for greenhouse studies. Strains of X. fastidiosa that were isolated from throughout California in the first 6 months of this project now are being examined for genetic differences by isolating bacterial plasmids and by using molecular probes that have been widely useful in distinguishing strains of other Gram-negative bacteria. The most genetically divergent strains will be inoculated into a range of plant host species to assess possible host range differences among strains of X. fastidiosa.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF1994-11-22 17:31:362017-11-22 17:32:19Pierce’s disease epidemiology and management