The first record and distribution of the fire blight pathogen Erwinia amylovora in Syria

Abstract

A survey of all major pome fruit growing regions was conducted during 2005 and 2006 to establish whether Erwinia amylovora, the causal agent of fire blight, was present in Syria. Samples were collected from quince (Cydonia oblonga), pear (Pyrus communis) and apple (Malus domestica) trees suspected of being infected with E. amylovora. Seventy-five isolates of E. amylovora were recovered, mainly from quince and some from pear but none from apple. All isolates produced typical symptoms of fire blight when tested on immature pear fruit. Two isolates were shown to induce a delayed hypersensitivity reaction on tobacco. All the isolates were confirmed to be E. amylovora by PCR using primers specific for this bacterium. One set of primers amplifies a fragment of the native plasmid (pEA29) and a second set amplifies a fragment involved in the synthesis of amylovoran, the structurally unique exopolysaccharide of this bacterium. Fire blight was found to prevail in the Al-Zabadani region (Rif Damascus), an area with a moderate temperature range (10–29°C) and high relative humidity (above 70%) during the blossom period. However, the diseasewas found to be restricted within Syria and observed only in isolated foci near the Lebanese border. This is the first isolation and identification of E. amylovora from Syria