Epidemiological study: Influence of weather parameters on false smut of rice [Ustilaginoidea virens (Cooke) Takahashi] in South Gujarat

Abstract

Rice (Oryza sativa L.) is a major staple food grain crop provides nutrition to more than half of the world. In India no single diet were completed without rice or its recipes. Rice was cultivated in all corners of India. The false smut of rice is important and major disease on rice. For the management aspect of any disease its epidemiology and climatic situation play an important role for initiation, growth and development of disease. The current research was laid during kharif 2023 and 2024 at HMRS, Waghai, Dist. The Dangs, NAU, Navsari. The first symptom of disease appears at 80-90 DAT on rice where crop was at initial flowering to pre panicle stage during the research period. In the year 2023 and 2024, percent disease incidence (PDI) was recorded in 37th MSW to 42th MSW (0.20 to 1.98%); (0.10 above 97 percent, rainfall above 200 mm in minimum days, respectively play important role in initiation of the disease. While no rainfall, 25-34 °C temperature range and relative humidity ranges at 66-97 percent was slowed down disease progress in both year. The temperature maximum and morning relative humidity were positive correlate with disease incidence and progress but rainfall and rainy days, wind velocity, minimum temperature and relative humidity evening were negatively correlated. The regression coefficient based on stepwise regression analysis, resulted that R-value in 2023 and year 2024 was high (0.950, 0.950) indicating a strong association between percent disease incidence to maximum temperature and minimum temperature in year 2023 and with them morning relative humidity (%) in the year 2024 climatic parameter. The co-efficient of determination value was found to be 90 and 89 percent in research year 2023 and 2024, respectively prove that our weather parameter model was satisfactory explain the relationship between disease prevalence and climatic condition.