In vitro evaluation of single and combined formulations of the fungicides against rice blast caused by Magnaporthe oryzae Cav.

Rice blast is one amongst the most devastating diseases caused by Magnaporthe oryzae Cav. (anamorph Pyricularia oryzae (Cooke) Sacc.)and are major constraints in the global rice production. Amongst the various strategies used for managing rice diseases, fungicides are of vital importance. So, in order to assess the efficacy, the seven commercial fungicides were tested under in vitro condition for their inhibitory activity through poisoned food technique and spore germination test at different concentration. In vitro evaluation of fungicides against M. oryzae disclosed that tricyclazole + tebuconazole (36% SC), tebuconazole 25% SC, hexaconazole 5% EC, zineb 68% + hexaconazole 4% WP and tebuconazole 50% + trifloxystrobin 25% WG completely inhibited the growth of fungus and germination of fungal spores in all concentration when compared with the control. Carbendazim 50% WP suppressed the blast pathogen in all concentrations except at 6.25% of recommended dose but it could inhibit the germination of spores only up to 50% of the recommended dose whereas tricyclazole 75% WP failed to inhibit completely the growth of fungal mycelium and spore germination.