Outbreak of Rice Blast on the Coastal Region of South-Eastern India

Rice blast caused by Magnaporthe grisea is turn to be one of the most severe pathogen under change in climatic condition in coastal region of South-Eastern India. Severity of the pathogen was not overwhelming previously. An investigation was carried out in several villages of different districts of Andhra Pradesh and Odisha under the RAWEP programme of Centurion University of Technology and Management with compared to meteorological data support from IMD, Bhubaneswar, Odisha. Different meteorological factors consider under this study were maximum temperature (T_max), minimum temperature (T_min), relative humidity maximum (RH _max), relative humidity minimum (RH _min), rainfall (RF). Among the three cultivated rice varieties, Pooja and Samba mahsuri (BPT-5204) are the most susceptible blast varieties (5.71% and 4.85%) compared to Swarna (MTU 7029) with a disease incidence level of 1.23%. Outcome of this investigation also revealed that the most crucial two (T_max and _{RH max) factors directly involved for the emergence of the disease compared to previous year 2015–16 and 2016–17. The peak disease infestation was observed in the month of October and November with PDI of 27.33% and 26%. Farmers based prolonged survey report and our observation concluded with the fact that Tricyclazole 75% WP (trade name-BAAN/Indofils) and 40% EC formulation of Isoprothiolane (trade name-Fujione/Rallis India Limited) are the two sequential most effective fungicides compared to different market based available fungicides and showed best efficacy against neck, collar and leaf blasts. Weather parameters as well as complex adaptability of the pathogenic nature (showing resistant against different fungicides) turned this Ascomycota member to a severe one.}

The highest rice blast disease incidence was observed in October and November. For epidemiological perspective, the two most crucial factors for the disease development are Maximum temperature, Relative humidity and Rainfall which make a tridirectional pool for disease development.

From the varietal study, it was seen that Pooja and Samba mashuri is the susceptible variety towards rice blast disease while Tricyclazole 75% WP and Isoprothiolane 40% EC is detected as two effective chemical against this disease.