Characterization of Myoviridae and Podoviridae family bacteriophages of Erwinia amylovora from Hungary - potential of application in biological control of fire blight

Twelve bacteriophage isolates of Erwinia amylovora, the causal agent of fire blight, were isolated from blighted apple, pear and quince trees from different sites in Hungary. According to morphological characteristics they were assigned to the order Caudovirales, two isolates belonging to the Podoviridae and ten to the Myoviridae families. Examining plaque morphology, host range and molecular characterization by PCR established that these phages are not identical neither to the three North American strains used as references nor the earlier isolated Hungarian Siphoviridae strains. Studying the efficacy of selected phages in apple blossoms and green pear fruit slices it was found that a combination of three phage isolates (ΦEaH2A, ΦEaH5K and ΦEaH7B) significantly reduced bacterial multiplication and fire blight symptoms as compared to untreated controls. Combined application of these new E. amylovora-specific phages as biocontrol agents may contribute to a better control of E. amylovora under field conditions.