Pathogenicity of Pseudomonas morsprunorum in Relation to Host Specificity

Abstract

SUMMARY: Differences in phage type between plum and cherry strains of Pseudomonas morsprunorum were stable during passage through the homologous and heterologous hosts. In experiments controlled by phage typing reisolates from lesions, both strains were specific for the homologous plant when inoculated into leaves at low concentrations (< 105/ml.) but not at high concentrations (> 106/ml.). No specificity was observed in wound inoculations of branches made during the winter. Autumn inoculation of cherry leaf scars with cherry strains resulted in severe disease, with a dose response type of relationship between inoculum concentration and infection. Plum strains were ineffective through cherry leaf scars and inhibited infection by cherry strains when present in the same inoculum. The inhibitory effect was not observed with plum strains killed by heat or streptomycin, or with plum strains inoculated live in the presence of bacteriostatic levels of streptomycin.