Survey of Cassava Mosaic Virus Disease Incidence in Farming Communities of Ogun State

Cassava mosaic virus disease remains the most economically important biotic constraint to cassava production in South West Nigeria, and updated field surveys tracking its current incidence and distribution are essential for guiding variety deployment and disease management advisory. This study surveyed the incidence and severity of cassava mosaic virus disease (CMD) in 40 farmer fields across Abeokuta North, Ijebu North, and Remo North Local Government Areas of Ogun State, South West Nigeria. Surveys were conducted during the 2023 growing season using a systematic random sampling protocol with ten sampling points per field. CMD incidence was calculated as the proportion of infected plants per field, and symptom severity was rated on a 1-to-5 scale. Variety information and management practices were recorded through structured questionnaires administered to 40 farmers. Results showed a mean CMD incidence of 41.8 percent across surveyed fields, with severity scores ranging from 1.8 to 4.3. Fields planted with unimproved local varieties showed significantly higher incidence (57.4 percent) than fields with improved CMD-resistant varieties (18.6 percent). Whitefly vector populations correlated positively with disease incidence (r = 0.62, p < 0.05). Most farmers (67.5 percent) were unaware of CMD-resistant variety options. The study concludes that CMD remains a widespread constraint in Ogun State cassava production. Recommendations include a state-level cassava variety replacement programme, farmer training on CMD symptom recognition, and enhanced IITA-NASC improved variety distribution systems. Keywords: cassava mosaic virus, CMD incidence, disease survey, Ogun State, South West Nigeria