Exploring novel fungicides to manage Alternaria blight disease in rapeseed-mustard

Abstract

Alternaria blight, caused by Alternaria brassicae (Berk.) Sacc and Alternaria brassicicola (Schw.) Wiltshire, is a widespread and economically significant disease of rapeseed-mustard (Brassica spp.). The disease is characterized by circular spots with concentric rings on leaves and pods, which later merge, leading to blighting of leaves. The disease is highly responsible for affecting mustard yield, causing yield losses up-to 50% and decreases the oil content by 14-36%. This field study was conducted in two successive rabi seasons (2022-23 and 2023-24) in order to evaluated the effectiveness of novel fungicides, including Tebuconazole 25.9% EC (Folicur), Propiconazole 25% EC (Albu), Penflufen 13.8% + Trifloxystrobin 13.8% FS (Evergol), Fluopyram 17.7% + Tebuconazole 17.7% SC (Luna), and Tebuconazole 50% + Trifloxystrobin 25% WG (Nativo), against Alternaria leaf spot. Among these, Fluopyram 17.7% + Tebuconazole 17.7% SC (Luna) showed the best results, with the lowest disease severity (3.83%) on leaves and (6.83%) on pods at 100 and 120 days after sowing (DAS) respectively. This was followed by Tebuconazole 50% + Trifloxystrobin 25% WG, which recorded 10.67 and 23.33 per cent disease severity on leaves and pods respectively, compared to the untreated control, which had 41.67 and 52.50 per cent disease severity. All fungicides significantly improved crop growth and yield. The highest yield was recorded in Luna (26.85 q/ha), followed by Nativo (24.85 q/ha), while the untreated control yielded only 17.28 q/ha.