Effect of weather parameters and sheath mite population on incidence and development of sheath rot disease of rice

Abstract

Paddy (Oryza sativa L.) is the world’s second most important cereal and staple food crop for people of south, south east and eastern Asia where 90 per cent of the world’s rice is produced and consumed. In the present study, field experiment was conducted on epidemiological studies during Kharif 2018 and 2019 at Main Rice Research Centre Farm, NAU, Navsari on susceptible cultivar GR-11 at natural condition. Effect of different weather parameters and sheath mite population were explored by correlation and regression analysis to find out their contribution to incidence and development of the rice sheath rot disease. The maximum sheath rot incidence (12.6%) and severity (10.30%) were occurred when favorable weather conditions viz., maximum temperature in range of 29.0 and 36.9 oC, minimum temperature in range of 20.3 and 24.7 oC, bright sunshine hours in range of 0.6 and 8.6 per day. Evening relative humidity in range of 50.0-97.6 per cent and sheath mite population in range of 0.95 to 7.95 mites per two cm rice leaf appeared. Correlation matrix was worked out and found that, significant highly positive correlation recorded with maximum temperature, bright sunshine hours and sheath mite infestation and played an important key role in the sheath rot development compared to other weather parameters. By employing stepwise regression equation model for sheath rot incidence revealed that at least 98% of variation in sheath rot incidence was explained by the function of weather parameters viz., minimum temperature and evening relative humidity and sheath mite infestation. Thus, weather parameters played a major role in sheath rot disease incidence in kharif season. Correlation matrix and step wise regression equation model established may be most reliable and useful for forecasting of the sheath rot disease of rice. The loss caused by the sheath rot can be saved by forewarning to the farmers and thereby controlling the same at the proper time.