Spread of olive knot disease caused by the bacteria Pseudomonas savastanoi pv. savastan in some regions of Syria

Abstract

Olive knot disease caused by the bacteria Pseudomonas savastanoi pv. Savastanoi is one of the most important olive tree diseases in the Mediterranean countries. Therefore, the aim of this research was to investigate the disease in some areas where olive trees are planted and to evaluate the incidence and severity of infection. The research was carried out in 2006-2007, where the survey included 237 fields in 10 governorates (Latakia, Tartous, Aleppo, Idleb, Homs, Hama, Daraa, Qunaitera, Damascus countryside, Suwayda). The results of the field survey showed the presence of the disease in 102 fields, which represent 43% of the total fields. The rate of infection was high in the governorates of Latakia and Tartous where it reached 69.9 and 61.4 respectively, while the lowest proportion was in Daraa and Quneitra (14.3% and 11.1%, respectively) and ranged between 20% and 35% in the other governorates. However, no disease was observed in both Damascus countryside and Sweida. 102 bacterial strains were isolated, they varied in it's aggressively by the number of tumors that occur on a branch, 32 isolates were highly aggressive, 58 were moderately aggressive and 12 were weakly aggressive.