Field surveys were carried out in the main Egyptian olive growing regions to verify whether olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, was present and to determine its geographic distribution and incidence/severity. The presence of typical disease symptom i.e. knots on olive branches and trunk was observed in EI-fayoum region, with low disease incidence and severity. The isolation of the pathogen from the olive knots was difficult to perform due to the massive and constant presence of a bacterium overgrowing in vitro, which we identify as Brevundimonas diminuta on the basis of its 165 rDNA sequence. However, 4 bacterial isolates whose colonies resembling those of the pathogen were isolated from olive knots. Morphological, biochemical, physiological, pathogenicity and molecular tests, showed that Egyptian isolates belong to P. savastanoi pv. savastanoi.
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Molecular characterization of these isolates performed with rep-PCR demonstrated 97-100% of similarity with the pathovar reference strain LMG 2209T of P. savastanoi pv. savastanoi. This is the first report of olive knot disease in Egypt.
