Study of fire blight disease using pathogenicity and streptomycin resistance diversity.
Fire blight of pome friut trees caused by Erwinia amylovora (Burrill) Winslow et al., 1920 has become one of the most important diseases of pome fruits in Iran. Ninety five strains of bacteria were isolated from affected tissues (leaves, branches, flowers and fruits). All samples 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 to tobacco and geranium. All 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 had homogenous phenotypic characteristics and antibiotics resistance, regardless of their original hosts or geographical areas. There was no chance of finding new species of E. pyrifoliae.