Investigations On Bacterial Soft Rot Of Vegetables With Special Emphasis On Soft Rot Of Carrot And Its Management

Abstract

The pathogen Pectobacterium carotovorum subsp. carotovorum isolated from newlinedifferent soft rot infected vegetables grew well on specific CVP medium with the formation newlineof characteristic pits indicating the production of pectolytic enzymes. This is unique newlinecharacteristic feature of the Pectobacterium spp. Among the differential media assessed for newlinethe growth and cultural characteristics, nutrient agar and peptone sucrose agar were found to newlinebe significantly superior in promoting the growth of the pathogen. The pathogen showed newlinepositive reaction for various physiological and biochemical properties except starch newlinehydrolysis. Among the different pectolytic enzymes, pectinase production was more newlinecompared to other enzymes. The temperature between 30- 35 °C and pH ranged between newline5.2- 7.6 was found to be best congenial for the maximum production of pectolytic enzymes. newlineAmong the different carbon sources pectin (Pectinase and Polygalacturonase), carboxy newlinemethyl cellulose (Cellulase) and skimmed milk powder (Protease) supported greater newlineenzymatic production. Among the 33 different isolates of bacterial pathogens subjected for newlinemolecular characterization, 20 were confirmed as P. carotovorum subsp. carotovorum and newline13 other isolates were characterized as P. aerugenosa, Pantoae sp. Pantoae agglomerans, newlineK. pneumonia, K. aerogenes, Aeromonas caviae, Providencia vermicola, Enterobacter newlinecloacae, P. atrosepticum and P. wasabiae. Among the 14 isolates, seven and ten isolates of newlineP. carotovorum were detected for the presence of streptomycin resistant genes strA and strB newlinerespectively. None of the isolates found positive for the copper resistant genes. Efficacy of newlinedifferent antibacterial compounds copper oxy chloride, Tagmycin, P. fluorescens, nilgiri newlineplant extract and cinnamon oil were significantly effective in inhibiting the growth of the newlinepathogen. Field and pot culture studies revealed that drenching with copper oxychloride at newline3g/ l followed by the treatment with soil application of P. fluorescens at 2.5 kg/ 100 kg FYM newlinealong with neem cake follo