Characterisation of Fusarium species infecting tomato in Mwea West Sub-county, Kirinyaga County, Kenya

Abstract

Fusarium species cause various diseases of tomato, the most common being vascular wilt and cortical rots. A study was carried out to characterize Fusarium spp. found in the stems of wilted tomato plants from farms in Mwea West Sub-county, Kirinyaga County, Kenya. Isolates were collected from tomato stems showing vascular discolouration. One hundred and one isolates of Fusarium spp. were obtained and classified based on their pathogenicity on the tomato cultivar ‘Money Maker’. The 10 most virulent isolates were identified by PCR amplification and sequencing of the TEF-1α gene as Fusarium oxysporum f. sp. lycopersici, Fusarium oxysporum and Fusarium verticillioides. Fusarium oxysporum f. sp. lycopersici causes vascular wilt in tomato, while F. verticillioides is known to infect maize, causing ear rot. The infection of tomato plants by F. verticillioides may reflect the rotation of tomato with maize in some fields, resulting in the accumulation of inoculum of this fungus and the subsequent infection of the tomato crop. The presence of vascular wilt caused by F. oxysporum and F. verticillioides suggests that strategies must be put in place to manage this disease. There is a need for surveillance by all agricultural stakeholders in order to check the progress of F. verticillioides that can infect tomato and other crops.