Evaluation of the Efficacy of Fungicides in Controlling Brown Spot (Bipolaris oryzae) Disease in Rice

Brown spot, caused by the fungal pathogen Bipolaris oryzae, poses a significant threat to rice production worldwide, leading to considerable economic losses for farmers. This study aimed to identify the most effective commercial fungicide for managing brown spot disease in rice. Eight commonly reported fungicides namely Azoxystrobin 23% SC, Diethane M45 75% WP, Hexaconazole 5% EC, Mancozeb 75% WP, Propiconazole 25% EC, Tebuconazole 25.9% EC, Tricyclazole 75% WP, and Trifloxystrobin 25% WG, were evaluated by poisoned food technique in vitro using four different concentrations (500, 1000, 1500, and 2000 ppm), each comprising of five replications. Among these, Tebuconazole, Tricyclazole, and Propiconazole demonstrated significant inhibition of B. oryzae growth compared to the controls during in vitro assessments. Interestingly, field evaluations conducted during the 2022 Rabi and Kharif seasons revealed that only Tebuconazole 25.9% EC exhibited the highest efficacy in controlling brown spot by showing the lowest disease incidence recorded at a concentration of 2000 ppm. Consequently, Tebuconazole 25.9% EC at 2000 ppm or 0.2% concentration is recommended for effective brown spot management in rice cultivation.