An experiment for the management of purple blotch of onion (Allium cepa L.) caused by Alternaria porri (Ellis) was carried out in Department of Plant Pathology, Rajasthan College of Agriculture, Udaipur during 2014-2015.Among 5 cultivars evaluated Nasik red showed susceptibility and Agri found light red showed resistance reaction against A. porri infection. Out of the six fungicides tested in vitro, Difenaconazole completely inhibited the mycelial growth of A. porri at concentration of 250, 500, 1000 and 2000 ppm, followed by Tebuconazole at 1000 and 2000 ppm. Neem formulations Azadirachtin was found effective in vitro followed by Garlic extract and Neem oil proved to be least inhibitor. Under pot culture study, combination of Difenaconazole and Azadirachtin was found most effective when applied as foliar spray. The application of fungicide and botanical resulted in significantly great disease control, over their individual applications as well as over untreated control. It would therefore, be desirable to apply integrated management practices to reduce the chances of development of resistance against fungicides, for effective and sustainable management of purple blotch of onion.

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