Management of Fusarium Wilt Disease of Tomato (Solanum lycopersicum L.) Using Selected Plant Extracts

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (Sacc.) Snyder and Hansen, is considered the most widespread, prevalent and economically damaging fungal disease of tomato in Nigeria. This study was conducted to isolate and identify fungal pathogens associated with tomato wilt disease, and also evaluate the efficacy of four plant extracts in the management of wilt disease in vitro and in vivo. Two varieties of tomato, Roma VF and UC 80 were used for the biocontrol assay. Four plant extracts, Zanthoxylum zanthoxyloides roots, Distemonanthus benthamianus stems, Azadirachta indica seeds and oryza sativa husk were evaluated against Fusarium oxysporum f. sp. lycopersici. Three concentrations (0.03, 0.04 and 0.05 g/mL) of each extract were investigated using the agar dilution method for radial growth inhibition assay. Of the four plant extracts evaluated, Oryza sativa husk extract was the most effective in inhibiting the growth of Fusarium oxysporum, both in vitro and in vivo. Rice husk extract (0.05 g/mL) had the highest inhibition rate (100%), followed by A. indica extract (80.32%) at 0.05 g/mL level of concentration, while Z. zanthoxyloides and D. benthamianus had the inhibition rates of 71.83% and 61.41% respectively, at 0.04 g/mL. Tomato plants treated with rice husk extract (0.05 g/mL) had the least wilt severity scores of 1.25 and 1.50 for both UC 80 and Roma VF varieties, respectively. Rice husk extract was the most effective against Fusarium wilt for both varieties and could serve as an alternative to synthetic chemicals in controlling F. oxysporum f. sp. lycopersici.