Delineating season-specific hotspots: A spatio-temporal risk assessment of neck blast disease in rainfed and irrigated ecosystems of Cumilla District, Bangladesh.

Rice blast disease, caused by Magnaporthe oryzae, is a major and foremost constraint to rice production in Bangladesh which threaten the food security and farmer livelihoods. This study delineates season-specific hotspots of the devastating rice Neck Blast Disease (NBD) across rainfed (Aman) and irrigated (Boro) ecosystems in the Bangladesh's most intensive rice cultivation area Cumilla District using spatio-temporal risk assessment. Multi-year field data (2017-2025) were analyzed through hierarchical clustering, Moran's I, Local Indicators of Spatial Association (LISA), and geostatistical interpolation techniques, including ordinary and indicator kriging. Results revealed spatial heterogeneity and inter-annual variability in disease severity. Nangalkot emerged as a persistent Aman-season hotspot, with mean NBD severity reaching 45-60%, while peak Boro-season severity reached 60-75% in several Upazilas, including Cumilla Sadar Dakshin, Debidwar, Barura, Burichang, and Nangalkot. Climatic trends correlated with neck blast disease intensification, particularly during reproductive stages. Indicator kriging effectively identified high-probability risk zones (>20% severity), enabling precise mapping of localized outbreaks. Findings of this study underscore the need for location-specific, adaptive management strategies integrating resistant cultivars and predictive modeling. This research offers actionable insights for policymakers and extension services to mitigate blast epidemics and safeguard Bangladesh's rice production under evolving climatic conditions.