Forty eight cultivars and seedlings of plum involving the species Prunusamericana, P.auqustifolia, P.cerasifiera, P.munsoniana, P.salicina, P.simoni, and P.triflora were evaluated for the presence of xylem limiting bacteria (Xyllelafastidiosa) and tree longevity. Plum leaf scald (PLS) ratings, based on the percent of scalded leaves in the tree were correlated with the concentrations of bacteria in the twigs and leaf petioles. Observations of symptoms of PLS and monitoring of progeny from interspecific crosses, cultivars, and seedlings indicate that resistance to the PLS organism is present in the Auburn material and heritable. Uniform infection of seedlings was made by double budding of one year whips with buds from infected trees. Resistance to PLS has been incorporated into horticultural types and seedlings are currently being evaluated for possible release for commercial and home use.