Abstract

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Unacquainted disease was reported at epidemic level in ginger crop in southwestern part of Ethiopia and induces heavy annual losses. To quantify the distribution of the disease, survey was conducted in Southern Nation Nationality and People Sate zones in 2012-and 2014 main crop season and covered 11 zones. In ginger farmers’ and private farm fields, it was observed that some plants with pathogenicity symptoms including yellowing of leaves and wilting, stunting growth and chlorosis. The prevalence of the disease was 100% but the mean maximum incidence was recorded in Sheka zone, 93.5%, followed by Benchmajizone, 91.6 %, while the lowest wilt incidence was recorded in Gamogofa zone 10.7 %. During 2014 season wilt incidence was increased to 98.9% and 97.4% in Benchmaji zone and Sheka zone respectively. In the same season 78.4% was recorded in Keffa zone. Alongside some studies was carried out to identify the causal organism of the disease; pathogenicity test and classify the strains on biovars, types and races. The result showed that the pathogen isolated and inoculated on disease free ginger plant generated from rhizomes produced through tissue culture have been developing identical symptoms to the symptom observed on the diseased plants at field conditions. Cultural characteristics of isolates on Tetrazolium Chloride (TZC) Agar selective medium showed light to red color with the characteristic red center which resembles the pathogen Ralstoniasolanascearum. Biochemical and physiological characteristic revealed that similarities among isolates and strains were grouped in biovar III and corresponds to race 4 of the pathogen.

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