Screening of different fungicides in controlling wheat blast in Bangladesh

Wheat blast caused by Magnaporthe oryzae pathotype Triticum (MoT) is an aggressive fungal disease threatening wheat production in Bangladesh. In the absence of resistant varieties, fungicide control is a first-hand effort. This study aimed to evaluate the performance of different fungicides against wheat blast in pot conditions and to identify the best one for preventive spray. The efficacy of five fungicides i.e., Nativo 75WG (Tebuconazole 50% + Trifloxystrobin 25%), Trooper 75 WP (Tricyclazole), Two in One (Hexaconazole 3% + Tricyclazole 22%), Opponent 75 WG (Tebuconazole 50% + Trifloxystrobin 25%) and Azonil 56 SC (Azoxystrobin 6% + Chlorothalonil 50%) against wheat blast was evaluated.  The blast susceptible variety BARI Gom 26 was planted in pot following CRD with three replications. Wheat plants (52 days old) were inoculated with spore suspension (10⁷ CFU) from 7 days old MoT cultures grown on oat meal agar at 25°C. Fungicides were sprayed at the pre-heading stage (52 DAS) after 48 hours of inoculation. Data on disease incidence and severity were scored for seven times after first appearance of disease symptoms.  The results indicate Nativo exhibited the highest level of fungicidal activity against blast with a 40.10% disease incidence and 91.81% severity, followed by Trooper with a 47.36% incidence and 97.45% severity. The diseases incidence for the rest three fungicides ranged from 53.90% to 85.10%. Nativo and Trooper showed 52.88 % and 44.35 % blast reductions respectively. It can be concluded that Nativo and Trooper fungicides can be used to control wheat blast by spraying twice at the 10 days interval at pre-heading stage.

Keywords: Wheat blast; Fungicides; Incidence; Severity