Effect of chemical and non-chemical management approaches in controlling wheat blast

Wheat blast caused by Magnaporthe oryzae Pathotype triticum (MoT) became one of the common nuisances to the expansion of wheat production in Bangladesh. To find out a suitable control measure, fourteen chemical fungi- cides and five Trichoderma asperellum isolates were evaluated against MoT in in vitro condition. In in vitro conditions the efficacies of fungicides and Trichoderma isolates were evaluated by the measurement of percent inhibition of radial mycelial growth of MoT. The highest percentage of radial mycelial growth inhibition (100%) of MoT was obtained by Mancozeb 63% + Carbendazim 12% (Companion), Carbendazim (Autostin 50 WDG), Py- rochlostrobin 5% + Metiram 55% (Cabrio Top), Tebuconazol (Folicur EW 250) and Hexaconazol (Contaf 5EC) fungicides at low concentration (0.0125%) compared to other fungicides at 10 days after inoculation (DAI). The maximum percent of radial mycelial growth inhibition (58.24%) of MoT was achieved by Trichoderma isolate PMILTE-N51 (58.24%) followed by isolate PMILTE- N41 (53.85%) in the in vitro dual culture assay at 7 DAI. In pot experiment, seven fungicides (Nativo 75WG, Companion, Autostin, Indofil M45, Supreme 250EW, Contaf, Amiscore 32.5 SC) at 0.1% & 0.3% and bioa- gents (T. asperellum, PMILTE-N51-suspension, PMILTE-N51- formulation and T. herzianum based IPM LAB- Formulation) were used to evaluate their efficacy in controlling wheat blast disease and their effects on different yield contributing parameters of wheat. Minimum percentage of blast incidence and severity were recorded for Supreme 250 EW @ 0.3% (14.88% and 2.21%) treated plants followed by PMILTE-N51 suspension compared to control (85.06% and 90.2%). Maximum number of ear/pot (13.67), number of total and healthy spikelets/ear (55.33 and 52.33), number of total and healthy grains/ear (50.33 and 45.67) were achieved by Amiscore 32.5 SC @ 0.3% followed by Supreme 250EW @ 0.3% and a maximum weight of 1000 grains/pot (55 gm) was recorded for PMILTE-N51-suspension, whereas controlled plants showed the lowest value for all the yield contributing parameters among the treatments used in this experiment. These results indicate that Amiscore 32.5 SC and Supreme 250 EW (@ 0.3%) showed the best results as chemical control approaches, where Trichoderma (PMILTE-N51-suspension) can be a better non-chemical management approach against wheat blast in Bangladesh.