INFLUENCE OFEPIDEMIOLOGICAL PARAMETERS ON DISEASE DEVELOPMENT OF PURPLE BLOTCH OF ONION [Alternariaporri (Ellis) Cifferi]

The present study entitled “Studies on epidemiological parameters on disease development of purple blotch of onion [Alternariaporri (Ellis) Cifferi]” was conducted in the Division of Plant pathology, P.G. Department of Agriculture, Khalsa College Amritsar, Rabi 2022-23.Onion (Allium cepa L.) is major vegetable crop cultivated primarily as food and export worldwide.It contains various anti-inflammatory, anti-cholesterol, anticancer and antioxidant properties with phytochemicals such as ‘quercetin’. It includes compound namely ‘Allyl propyl disulfide’ which is responsible for its smell, pungency and irritation of the eyes.Correlation of meteorological parameters viz., temperature, rainfall and relative humidity with respect to per cent disease index studied from 01/01/2023 to 28/04/2023 for sixteen weeks. Weather parameters temperature and rainfall was significantly positively correlated with PDI (0.937** and 0.525*, respectively), whereas, relative humidity was non-significantly negatively correlated with PDI (-0.495NS).