First report of Pseudomonas savastanoi pv. savastanoi causing olive knot in Syria.
During field surveys carried out in 2007 in the main Syrian olive (Olea europaea) growing areas, bacterial knot symptoms were observed on olive twigs and branches, with the highest incidence (70%) in the coastal region (Lattakia and Tartous). Ten selected representative bacterial strains were subjected to identification tests. All strains were Gram negative, fluorescent on King's medium B and had oxidative but not fermentative metabolism. They were negative for levan, oxidase, potato rot and arginine dihydrolase and positive for tobacco hypersensitivity. One-year-old olive plants (cultivars Nebali and Jlot) were inoculated by introducing bacterial suspensions (108 cfu/ml) into wounds made in the bark with a sterile scalpel. Bacteria with characteristics identical to the original strains were reisolated from inoculated plants. Based on morphological, biochemical, physiological and pathogenicity tests as well as molecular analyses, it was concluded that the Syrian strains belong to Pseudomonas savastanoi pv. savastanoi. This is thought to be the first authoritative report of olive knot disease symptoms in Syria caused by Pseudomonas savastanoi pv. savastanoi.