Prevalence of Wilt Diseases on Watermelon (Citrullus lanatus) in Ogun State, South West Nigeria

Watermelon (Citrullus lanatus) cultivation has expanded rapidly in Ogun State as smallholder and medium-scale farmers respond to strong demand from urban markets in the South West zone. Wilt diseases, associated with both soilborne fungi and bacterial pathogens, have been increasingly reported as barriers to sustained production in the state. This study investigated the prevalence of wilt diseases on watermelon across selected farms in four local government areas of Ogun State. Field visits conducted between April and August 2023 revealed widespread wilting symptoms involving both pre- and post-fruiting plants. Pathological examinations confirmed Fusarium oxysporum f. sp. niveum and Phytophthora capsici as the primary fungal agents responsible for vine wilting, with Acidovorax citrulli implicated in fruit rot symptoms. Total wilt incidence across all farms averaged 38 percent, with isolated plots recording as high as 60 percent infection rates. Heavy clay soils with poor drainage were significantly associated with higher Phytophthora-related losses. Many farmers reported abandoning previously productive fields after two to three seasons of repeated losses, suggesting the accumulation of soilborne inoculum. The study recommends the integration of resistant rootstocks, soil solarisation, and improved drainage practices into watermelon production systems in Ogun State. Extension officers should prioritise wilt disease education and demonstrate preventive options to reduce farm abandonment. Keywords: watermelon, Fusarium wilt, Phytophthora, Ogun State, disease prevalence.