Antagonists of Erwinia amylovora isolates from fire blight diseased fruit trees in Georgia

Fire blight, a devastating disease of pomaceous plants after its appearance in Kartli in 2016 has spread in some other regions of Georgia. A causative agent of the disease, Erwinia amylovora was detected by PCR using specific primers pair in different organs of symptomatic apple, quince and pear plants. King’s B, SNA and CCT agar media were used for maximum recovery of E. amylovora from these samples. Colonies of E. amylovora on NSA medium appear at 24 h and are whitish, circular, domed, smooth and after 48 h mucoid. Colonies of E. amylovora on CCT form only one morphological type and are pale violet, circular, highly convex to domed, smooth and mucoid after 72 h. Colonies on King’s B appear at 24 h and are creamy white, circular, tending to spread and non-fluorescent under UV light. PCR analysis, based on amplification of sequence near termini of the chromosomal pEA71 insert region confirmed that the isolates are E. amylovora. Out of tested 24 actinobacteria, four isolated from soils in Imereti ## 2IM, 3IM, 5IM and 8IM and two from soils of Samegrelo-Zemo Svaneti ##37A and 99A expressed antagonistic activity against E. amylovora isolates. These actinobacteria could by applied for biological control of fire blight.