Varietal reaction of onion cultivars against Alternaria porri causing purple blotch and its management

Abstract

Ten onion cultivars were evaluated during kharif 2021-22 and 2022-23 for their reaction to Alternaria porri under field conditions. Of them, three varieties viz., Arka Kalyan, Arka Niketan and Arka Bheema showed resistant reaction while two varieties viz., Rampura and Satara local were moderately resistant and rest were moderately susceptible. Among 10 fungicides, 10 botanicals and six bio agents evaluated in vitro against A. porri, 0.1%Azoxystrobin- 23EC, 0.1% Tebuconazole-25EC. Allium sativum (15%) and Trichoderma harzianum recorded the maximum inhibition of mycelial growth of Alternaria porri. The field evaluation of different fungicides and botanicals during indicated that 0.1% Tebuconazole-25EC was recorded minimum PDI of 22.68 and yield of 271.00q/ha. 0.1% Azoxystrobin- 23EC.0.1% Difenconazole-25EC.0.2%Mancozeb-75WP and Allium sativum cloves extract were next best treatments in reducing the disease intensity by recording PDI of 24.00, 26.00, 28.00 and 46.00 and yield of 268.00q/ha, 262.65q/ ha. 264.00q/ha and 234.65q/ha respectively. During kharif 2022-23 also 0.1% Azoxystrobin-23EC was found to be the effective treatment followed by 0.1% Tebuconazole-25EC.