INVESTIGATIONS ON BACTERIAL WILT OF SOLANACEOUS VEGETABLES CAUSED BY Ralstonia solanacearum (Smith)
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Date
2015-06-30
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UNIVERSITY OF AGRICULTURAL SCIENCES, RAICHUR
Abstract
Bacterial wilt of solanaceous vegetables caused by Ralstonia solanacearum (Smith) is the most devastating disease in tropical, subtropical and warm temperate regions of the world, leading to heavy economic loss. Considering the magnitude and resultant losses due to the disease, investigations were undertaken to study the disease, pathogen, variability and in vitro evaluation for management. The survey report revealed that the bacterial wilt incidence was highest in Narayanapura village of Hassan district and lowest disease incidence in Kappagal village of Ballari district. Global Positioning System (GPS) based survey indicated that, the per cent disease incidence of bacterial wilt varied from location to location (spatial variation). Bacterium is gram negative is rod shaped, non-capsulated and non-spore forming and is strictly aerobic. On TZC medium, virulent colonies are irregular to round, fluidal, white cream coloured having pink to red tinge at the centre, surrounded by white mucilod layer. Avirulent colonies are round in shape, butyrous, deep red in colour and not surrounded by narrow white border. On CPGA medium the colonies are small, irregular to round, flattened, white to light cream coloured surrounded by muciloid layer without any pink or red tinge at the centre. The pathogen is positive for gelatin liquefaction, catalase, oxidase and KOH solubility test and negative for starch hydrolysis and levan production from 5 per cent sucrose. The isolates exhibited 100 per cent polymorphism for OPH-01, OPH-03, OPH-11 and OPF-01primers showing significant molecular variability. Among the antibiotics tesed, bacterinol-100 was found to be highly effective in inhibiting the growth of R. solanacearum and copper hydroxide exhibited superior efficacy among antibacterial chemicals. Among bioagents Pseudomonas fluorescens was found significantly superior in inhibiting the growth of pathogen.
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