Survey of Cassava Bacterial Blight (Xanthomonas axonopodis pv. manihotis) in Ogun State, South West Nigeria

Cassava Bacterial Blight (CBB), caused by Xanthomonas axonopodis pv. manihotis, is among the most economically significant bacterial diseases affecting cassava production in sub-Saharan Africa. Though various studies have documented CBB incidence in South West Nigeria, detailed field surveys in Ogun State remain limited. This study undertook a systematic survey of CBB incidence and severity in cassava-producing communities across five local government areas in Ogun State during the 2023 growing season. Field assessments used belt transect methods, with disease scoring based on foliar blight, wilting, dieback, and angular water-soaked lesion symptoms. X. axonopodis pv. manihotis was confirmed through selective isolation, biochemical characterisation, and pathogenicity assay. Overall CBB incidence was 43 percent, with the highest concentration in farms using stem cuttings sourced from infected fields. Disease severity was significantly higher in plots planted at the onset of the wet season, when rainfall favours rapid bacterial spread through splash dispersal. Surveys revealed a consistent pattern of farmers sourcing planting material from neighbours rather than from certified clean seed distribution channels. The study calls for strengthening of the certified cassava seed multiplication and distribution system in Ogun State and recommends roguing and destruction of infected plants as a low-cost management option accessible to subsistence farmers. Keywords: cassava, bacterial blight, Xanthomonas, Ogun State, disease survey.