Characteristics of isolates of Pseudomonas solanacearum in Ethiopia
1989
Yaynu Hiskias (Scientific Phytopathological Laboratory, Ambo (Ethiopia))
Bacterial wilt caused by Pseudomonas solanacearum E.F. Smith is an important disease of potato and tomato in many parts of Ethiopia. Isolates were collected from potato and tomato from eight locations and pathogens were characterized during 1985-1987. Cultural characteristics of 58 isolates on tetrazolium chloride agar medium showed variability in colony size and pigment formation. In contrast, physiological characteristics revealed no differences. All isolates utilized disaccharides --maltose, lactose, and cellobiose -- but did not oxidize hexose alcohols -- mannitol, sorbitol, and dulcitol. Based on these characteristics the isolates were classified as biovar II. Hypersensitivity and pathogenicity tests showed slight differences among isolates. Most isolates caused yellow chlorosis while a few others induced hypersensitive reaction on infiltrated tobacco leaves after 24 h. In a pathogenicity test with five solanaceous hosts, all isolates caused wilting of potato, eggplant, and tomato. In addition, a few isolates also infected tobacco plants slightly but none infected pepper. On the basis of the pathogenicity tests the isolates were classified as race 3, which also corresponded to biovar II of the pathogen
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