Study of Fire blight disease using pathogenicity and streptomycin resistance diversity

Fire blight of pome friuts trees caused by Erwinia amylovora (Burrill) Winslow et al., 1920 has become one of the most important disease of pome fruits in Iran.Ninty five strains of bacteria were isolated from affected tissuse(leaves,,branches, flowers and fruits) all isolates were compared according to the standard physiological, biochemical and pathogenicity tests. Sensitivity of strains against some antibiotics such as streptomycin, oxytetracyclin and copper were determined.All strains produced hypersensitive reaction in tobacco and geranium. All of strains were the same in phenotypic characteristics moreover there was not any difference in disease severity between different strains. None of strains tested were resistant to streptomycin, oxytetracyclin and copper. All strians were homogenous phenotypic characteristics and anyibiotics resistance, regardless of their original hosts or geographical areas. There is no chance of finding new species of E.pyrifoliae.