Spatiotemporal Analysis of Cassava Bacterial Blight Outbreaks in Ogun and Oyo States, South West Nigeria, 2020 to 2024

Cassava Bacterial Blight caused by Xanthomonas axonopodis pv. manihotis is a recurring epidemic constraint in South West Nigerian cassava systems, yet rigorous spatiotemporal analyses linking outbreak dynamics to landscape and management factors have not been conducted for this region. This study performed spatiotemporal analysis of CBB outbreaks recorded across sentinel farms in Ogun and Oyo States between 2020 and 2024. Geo-referenced disease incidence data from 150 farms were collected at six-week intervals using standardised field protocols, supplemented by satellite-derived land use classification and monthly rainfall records. Spatial scan statistics identified significant disease clusters across both states, with outbreak hotspots concentrated in zones characterised by continuous cassava cultivation and high farm connectivity through shared planting material networks. Temporal trend analysis using Mann-Kendall tests detected a statistically significant upward trend in CBB incidence in Ogun State across the study period, coinciding with increased dry-season irrigation of cassava. Rainfall event frequency was the strongest climatic predictor of outbreak initiation date, consistent with the splash-dispersal mechanism of X. axonopodis pv. manihotis. Network analysis of planting material sharing practices revealed that CBB spread across administrative boundaries was primarily attributable to long-distance movement of infected cuttings rather than natural pathogen dispersal. The study contributes a spatiotemporal outbreak dataset and identifies planting material network structure as the critical intervention point for CBB management in South West Nigeria. Keywords: Cassava Bacterial Blight, spatiotemporal analysis, Xanthomonas, outbreak dynamics, South West Nigeria.