PREVALENCE OF BACTERIAL WILT PATHOGEN Ralstonia solanacearum OF POTATO IN SELECTED DISTRICTS OF NORTHERN BANGLADESH AND ITS in vitro MANAGEMENT BY SOME AGROCHEMICALS

Abstract

Several varieties of potato viz. cardinal,granola,diamant,asterix,laura,cumbica were collected from selected districts of northern Bangladesh viz. Rangpur, Naogaon, Lalmonirhat, Kaunia through different potato producing companies viz. Tradelink International Ltd., Ashmina, Shahan Trade International, Hay Agro during December, 2014 to August, 2015 to evaluate prevalence of bacterial wilt of potato (Ralstonia solanacearum) for developing suitable in vitro agrochemical management. Ralstonia solanacearum was isolated from collected potato tubers and it’s morphological, biochemical and cultural features were studied. The bacterium was gram negative, rod shaped and showed positive result in KOH solubility test, catalase test and pectolytic test and negative result in oxidase test, turbidity test and for some samples in pectolytic test. Some produced largely unmixed mucoid magenta deep red coloured colonies and some produced pink coloured with whitish margins on TTC medium. On NA medium, circular, mucoid, convex, lucid coloured colonies of bacterium were formed. After observing the features, pathogenic and non pathogenic bacteria were identified. In vitro efficacy of different agrochemicals was observed against pathogenic bacteria identified. In vitro evaluation of agrochemicals exhibited that among the agrochemicals Deoxymethasone (Neomycin) in 0.5% concentration and Streptomycin in 0.5% concentration were highly effective against Ralstonia solanacearum causing bacterial wilt of potato. Copper compounds (Cuprofix), Mancozeb (Indofil M-45 and Ridomil gold) showed satisfactory efficacy in 0.5% concentration against the pathogen.