Occurance of pear and apple blast disease in Razavy and North Khorasan Provinces

During 2006-2009 canker symptom and blast in pear (Pyrus communis) and apple(Malus communis) trees were observed in several orchards. The symptoms partly resembled to fire blight disease caused by Erwinia amylovora, except for the absence of gum exudation the affected tissues. A gram-negative, rod-shaped and aerobic bacterium was consistently isolated from affected tissues. All colonies produced levan on SNA(Sucrose nutrient Agar). Fluorescent pigment was produced on King,s B medium. Strains were catalase positive, oxidase and arginine dihydrolase negaative and did not rot potato tuber slices. They showed negative reaction for starch and esculin hydrolysis, production of acetoin, indole and H2S. Six strains produced syringomycin and a hypersensitive reaction in tobacco and geranium. Froctuse, glucose, galactose, sucrose, mannose, mannitol, glycerol, citrate, fumarate, succinate and lactate used as carbon sources. No strain utilized maltose, inulin, starch, dextrin, oxalate, formate or benzoate. Based on these and additional characteristics, the strains were identified as pseudomonas syringae pv syringae. Pathogenicity tests on twings and seedlings of a local cultivar of pear was performed by two strains. This is the first report of apple blast occurence in Iran