ISOLATION, DIAGNOSIS, AND İN VİTRO BIOLOGICAL CONTROL OF THE OLIVE KNOT PATHOGEN Pseudomonas savastanoi pv. savastanoi.

In this study, 18 olive production areas in Mersin and Osmaniye provinces were visited and 26 pathogenic bacterial strains were isolated from 6 infected trees showing knot disease symptoms. The pathogenic bacterial strainswere identified as Pseudomonas savastanoi pv. savastanoi by Gram Reaction with potassium hydroxide test, LOPAT characters, pathogenicity tests on carrot slices and pathogenicity test on olive branches and MALDI-TOF tests based on peptide mass fingerprint analysis of proteins of bacterial strains. In biological control research, the antibacterial effect of 19 epiphytic and endophytic antagonist bacterial strains in the culture collection of our department was investigated by in vitro petri trials. In the dual culture test, all antagonists suppressed the growth of the pathogen and formed an inhibition zone between 2.00mm-9.33mm. Five antagonists in the same statistical group (KSY9, ABK-FY-2-5, MTHM3, FT2.1, MTHM2) were the most successful isolates in inhibiting pathogen growth. KSY9 coded strain was determined as the most successful antagonistic strains with an average inhibition zone of 9.33 mm. In the MALDI-TOF diagnostic tests of the successful antagonists, it was determined that all of them were isolates belonging to the genus Bacillus. This study highlights the importance of biological control, which is one of the environ mentally friendly and organic farming methods used to suppress diseases.