Host resistance and interaction between root knot nematodes and fusarium wilt of tomato

Abstract

Tomato (Solanum lycopersicum L.) is one of the most popular vegetable crops grown worldwide, owing to its nutritive value, income generation and diversified use. Tomato cultivation in the coastal region of Kenya is limited by root knot nematodes (Meloidogyne spp.) and Fusarium oxysporum. A survey was done in five farming counties of the Coastal region of Kenya. Meloidogyne spp. and F. oxysporum were isolated from diseased tomato plants and identified. Host resistance and interaction between root knot nematodes and Fusarium wilt pathogens was evaluated on five tomato cultivars under screen house and field condition. Root knot nematodes identified were Meloidogyne incognita, M. javanica and M. arenaria. However, there was a novel species that was also isolated and identification is ongoing. Combined inoculation of Meloidogyne spp. and F. oxysporum caused a significant reduction (p ≤ 0.05) in crop growth (shoot height, shoot dry weight, root length, root dry weight) when compared to the un-inoculated controls or single pathogen inoculated treatments. When inoculated singly, Meloidogyne spp. reduced crop growth significantly (p ≤ 0.05) than F. oxysporum inoculated. The population of Meloidogyne spp., number of galls and egg masses were significantly lower (p ≤ 0.05) when the Meloidogyne spp. and F. oxysporum were inoculated in combination. Cultivar Okistu 101 was tolerant to nematodes-Fusarium wilt disease complex and had the highest fruit weight (6371g). Tomato cv. Hawaii 7996 was resistance to disease complex and needs to be introduced into tomato farming system in Kenya.