Synthetic fungicides for controlling brown leaf spot of rice caused by Bipolaris oryzae

Abstract

Rice (Oryzae sativa L) is suffering from several biotic and abiotic factors. Among biotic factors, brown leaf spot of rice (BLS) is potentially devastating disease of rice causing the severe yield losses up to 100%. The current study was designed to evaluate most effective synthetic fungicides management strategy towards BLS disease. For this purpose, 12 fungicides were screened out under in vitro conditions and four most effective fungicides were further demonstrated against the targeted pathogen with three different concentrations (100, 150 and 150 ppm) by using poisoned food technique. The results revealed that propiconazole and thiophanate methyl showed the strong inhibitory effect against B. oryzae followed by contaf plus and bavistin respectively. The promising fungicides (propiconazole and thiophanate methyl) under lab conditions were further evaluated in vivo against BLS disease by using 3 types of applications i.e. Pre-inoculation, Post-inoculation and after symptoms appearance. Findings showed that, Post-inoculation was found most effective as compared to other applications, furthermore combination of propiconazole and thiophanate methyl showed significant reduction in disease incidence percent as compared to solo applications. The reduction in disease incidence percent in all application methods suggested that these synthetic fungicides could be used against BLS of rice.