Comparative Assessment of Fungicidal Efficacy against Alternaria brassicae in Mustard under an in vitro Condition

The effectiveness of five commercially available fungicides against Alternaria brassicae, the causative agent of Alternaria blight in mustard (Brassica juncea), was assessed in an in vitro study. Radial growth inhibition was assessed using the poisoned food approach at four different concentrations (50, 100, 150, and 200 ppm). With a definite dose-dependent response, all fungicides dramatically decreased fungal growth as compared to the untreated control. The most effective combination of treatments was Azoxystrobin + Tebuconazole, full inhibition at 100 ppm. While copper oxychloride and chlorothalonil were somewhat ineffective and did not achieve total inhibition at any tested concentration, azostrobin alone and captan + hexaconazole were moderately effective. The results indicate that systemic and combination fungicides, especially formulations based on azoxystrobin, have a great chance of being incorporated into integrated disease management plans to combat A. brassicae in mustard farming.