Management of Alternaria leaf spot of cauliflower caused by Alternaria brassicicola (Schwein) Wiltish through new molecule of fungicide

Abstract

Alternaria leaf spot, caused primarily by Alternaria brassicicola, is a major constraint in cauliflower production. In the present study, six new molecule commercially available fungicides were evaluated for their efficacy against A. brassicicola through poisoned food technique (in-vitro) done with pot and field experiments (in-vivo). Among the treatments, Tebuconazole 50% + Trifloxystrobin 25% WG and Azoxystrobin 4.7% + Mancozeb 59% + Tebuconazole 5.6% WG exhibited complete (100%) inhibition of mycelial growth at 250 ppm and consistently outperformed others in reducing disease severity in both pot and field conditions. In pot trials, the lowest Percent Disease Index (PDI) was recorded with Tebuconazole + Trifloxystrobin (3.25%), followed by Azoxystrobin + Mancozeb + Tebuconazole (4.06%). Similarly, in field trials, the same treatments gave PDI of 3.37% and 4.49%, respectively, after the second spray. Carbendazim 12% + Mancozeb 63% WP was the least effective treatment among all treatments. The findings suggest that strobilurin-triazole fungicide combinations offer superior protection and can serve as an integral component of an integrated disease management strategy for sustainable control of Alternaria leaf spot in cauliflower.