Bacteriophage of Erwinia amylovora - Host Range and Fire Blight Control Potential

Abstract

In search for an alternative to chemical control of fire blight, we isolated seven bacteriophages specific to E. amylovora. Three phages were isolated from water, three from symptomless pear leaves and one from apple leaves with characteristic fire blight symptoms. Host-range studies showed that the phages differed in the ability to lyse 40 strains of E. amylovora isolated in Serbia. Based on its lytic activity, phage Phi Ea2 was chosen for further study of biological control potential in pear and apple blossom bioassays. A phage suspension of 10(8) PFU/ml was applied on blossoms either 2 h before, 2 h after or at the same time of inoculation. In three fully replicated bioassay experiments, application of host-specific phages 2 h before inoculation and at the time of inoculation significantly reduced fire blight symptom development compared to untreated control. However, disease reduction was not significant when phages were applied 2 h after inoculation.