Effect of weather parameters on incidence of purple blotch in onion

Red onion entries Bhima Red, Bhima Super, Bhima Shakthi and White Onion entries Bhima Shwetha and Bhima Safed were tested for the incidence of purple blotch in onion at Vegetable Research Station, Rajendranagar. Bhima Red, Bhima Super, Bhima Shwetha and Bhima Safed were tested during kharif, 2023 Bhima Red, Bhima Super, Bhima Shwetha and Bhima Safed and Bhima Shakhi during late kharif 2023-24, Bhima Shwetha and Bhima Shakthi during rabi 2023-24 as part of All India Network Research Project on Onion and Garlic. The incidence of purple blotch (PDI) was recorded on a scale of 0-5 (0: No incidence, 1:1-10%, 2:11-20%, 3:21-30%, 4:31-50% and 5:51-100%). All the tested entries showed purple blotch incidence during all the seasons. All the entries tested during kharif recorded a rating of 2 on a scale of 0-5, during late kharif conditions Bhima Red and Bhima Safed recorded a rating of 1 (1-10% PDI) and Bhima super, Bhima Shakthi and Bhima Shwetha recorded a rating of 2 (11-20% PDI) and during rabi season both the entries tested Bhima Shakti and Bhima Shweta recorded low incidence of purple blotch a rating of 1 (1-10% PDI) on a scale of 0-5. High amount of precipitation, higher relative humidity coupled with warm temperatures during kharif and late kharif seasons might have resulted in the greater incidence of purple blotch and promotion of higher disease development than in rabi with lower relative humidity.