Relative Resistance of some Local and Commercial Cherry Genotypes to Pseudomonas syringae

In this research, relative resistance of leaf and shoot of sixteen local genotypes and seven commercial sweet cherry and sour cherry cultivars to Pseudomonas syringae was studied in glasshouse condition. Shoot evaluation was performed by inoculating winter shoots and leaf evaluation by direct inoculation, inoculation in water-agar medium and using vacuum pump. A pathogenic strain of P. syringae was isolated from an infected sweet cherry tree in Karaj, identified by phenotypic and molecular methods and used as inoculum. Based on the results, high variation was observed in leaf and shoot reactions to the bacterium. Grouping based on shoot resistance levels indicated that 43.5% of genotypes were relatively resistant, 43.5% intermediate and 13% susceptible. Hamedan and KB8 were rated as the most susceptible and resistant genotypes, respectively. The most efficient method for leaf inoculation was through using vacuum pump. The results of this method indicated that 6% of genotypes were relatively resistant, 35% intermediate and 59% susceptible. Blamarka and Dirres-e-Daneshkade were rated as the most susceptible and RD Jobileum as the most resistant genotypes. As no correlation was observed between leaf and shoot susceptibilities, leaf susceptibility level could not be indicative of resistance of shoots to bacterial canker.