ASSESSMENT OF YIELD LOSSES CAUSED BY PURPLE BLOTCH DISEASE IN ONION (ALLIUM CEPA L.) AND ITS MANAGEMENT

Abstract

Onion is one of the most important commercial vegetable crops grown in Pakistan. It is valued for its distinct pungent flavor and is an essential ingredient for the cooking in many regions. A number of diseases attack onion crops but purple blotch is the most important one and cause huge losses in different parts of world. To search out sources of resistance against this disease, twenty one varieties/ lines were evaluated against it. Not a single variety out of all varieties screened showed highly resistant/immune response towards disease. One variety i.e. Phulkara, exhibited resistant response, while five varieties/lines i.e. Desi red, Early red, Robina, Dark Red and Mirpurkhas showed moderately resistant response.VRIO-6, VRIO-1, VRIO-4 Red nasik, Desi black expressed moderately susceptible response and  five i.e.VRIO-9, Pak-10321, Faisalabad Red, Pusa red, Red imposta expressed susceptible reaction while VRIO-3, VRIO-5, VRIO-8, VRIO-7, VRIO-2 showed maximum disease development with rating 5 towards purple blotch disease. For management, three fungicides and three plant extracts at three different concentrations were evaluated against purple blotch disease of onion under field conditions. Among these fungicides Mancozeb expressed minimum disease incidence, followed by Score, Dorazole, and Dora as compared to control. Among the plant extracts Moringa oleifera expressed minimum disease incidence followed by A. indica and A. sativum as compared to control. The present study will be helpful in order to manage the purple blotch disease in onion.