Mehta, P. B.Sharma, Pradeep2018-06-182018-06-182000-10PRADEEP SHRMA_32615http://krishikosh.egranth.ac.in/handle/1/5810053589Cabbage (Brassica oleracea var. Capitata) is one of the important cole crops grown as winter vegetable in Gujarat. Among different diseases, black rot of cabbage, caused by Xanthomonas campestris pv. campestris (Pammel) lJowson, is one of the most destructive diseases throughout South Gujarat. Considering the seriousness of the problem, the present studies were carried out to generate more infOllIlation for developing suitable control measures. The isolation from infected cabbage leaves revealed the association of Xanthomonas sp. with black rot. The pathogenicity of Xanthomonas sp. was proved by artificial inoculation methods viz., tooth brush injury, pin pricking, carborundum powder injury and spraying of inoculum without injury with positive results. Thepathogenicity was confirmed upon detached leaves as well as in pot culture. Results of morphological, cultural and biochemical tests tallied with the reports of the earlier workers. Upon nutrient agar medium, pathogen produces creamy yellow, smooth, circular, bright raised colonies, while upon tetrazolium, fiat, dark brown, circular and smooth colonies. The pathogen is recorded for the first time in Gujarat. Among the various solid media tested, nutrient agar, SX agar and yeast glucose chalk agar were proved best for studying the growth and colony characters of Xanthomonas campestris pv. campestris. Fructose and sucrose were proved to be better while starch, galactose, mannitol, lactose and glucose were inhibitory sources of carbon. Di-ammonium hydrogen orthophosphate and potassium nitrate accelerated the growth while ammonium oxalate, sodium nitrate, arrunonium nitrate, urea and arrunonium sulphate inhibited the growth of the bacterium. Thermal death point of the pathogenic isolate was 52°C. Host range studies comprising of eight different plant and weed species belonging to different families indicated that X campestris pv. campestris readily infected three species namely cauliflower, mustard and radish belonging to family €ruciferae, which are the known hosts of this bacterium while. the leaves of brahmi showed the epiphytic survival of X campestris pv. campestris. Seed borne nature of the bacterium was detected by using moist blotter paper technique. Seed lots of susceptible variety'Golden Acre' and 'Pride of India' consisted more number of infected seeds than other varieties tested. The phyto-extracts of twenty two plant species were screened in vitro by paper disc method against X. campestris pv.campestris, gando baval proved strongly inhibitory followed by garlic bulb, sankal chain, turmeric rhizome, black basil and eucalyptus. In vitro screening of chemicals were carried out by the paper disc method, indicated that Streptocycline and MEMC (Emisan) were highly bactericidal to X campestris pv. campestris followed by Agrimycin, Mercuric chloride, Zirum (Cuman-L), Captafol (Foltaf) and Mancozeb (Dithane M-45). Among the fungicides and/or antibiotic and hot water treatment tested for their efficacy in eliminating seed borne infection of the bacterium, hot water (50°C for 30 minutes), Streptocycline (0.01 per cent) and Mercuric chloride (0.01 per cent) were found comparatively more effective. Inoculation of seeds with the culture of X campestris pv. campestris reduced their gellnination but, when the inoculated seeds were tested with Streptocycline and hot water, the ee7' OO) seed germination was improved, maximum seed genninatiol'.A was in Streptocycline (0.01 per cent). Among six evaluated cabbage varieties against the black rot, Hybrid NS-27, Hybrid NS-22 and Midorimaru were resistant, Express was moderately resistant while Golden Acre and Pride of India were highly susceptible under both natural and artificial inoculated conditions.ennullThesis