Evaluation of rice blast disease in key cultivation regions of the Indo-Gangetic plains

A comprehensive survey on the incidence and severity of rice blast disease was conducted across six major rice-growing districts in the Indo-Gangetic plains of West Bengal. The assessment was based on symptomatic evaluation of different rice varieties, including Satabdi, Khitish, Lal Minikit, and Rajendra Bhagabati, during the tillering stage, which are predominantly cultivated by farmers in these regions. This study aimed to assess disease incidence and severity to inform cultivar selection and blast management strategies in West Bengal. The pooled data from the two-year study period (2020 and 2021 Rabi seasons) indicated that Malda district exhibited the highest disease incidence (DI) at 29.17% and the highest Percent Disease Index (PDI) at 25.99%. Conversely, Howrah district reported the lowest DI (12.04%) and PDI (5.84%). The data demonstrated an increase in both DI and PDI across all surveyed districts in 2021 compared to 2020. Overall, the mean DI ranged from 12.04% to 29.17%, while the PDI varied from 5.84% to 25.99%. This survey study highlights the spatial variability in rice blast disease incidence and severity, emphasizing the need for targeted disease management practices and the development of resistant rice cultivars to mitigate the impact of rice blast in the Indo-Gangetic plains.