EVALUATION OF ANTIMICROBIAL ACTIVITIES OF Tithoniadiversifolia AND Kigeliaafricana AGAINST TOMATO FUSARIUM WILT PATHOGEN (FusariumoxysporumLycopersci)

Abstract

Fusarium wilt disease caused by the soil-borne fungusFusariumoxysporum Schlechttheisaserious threat to tomato production worldwide. Chemical and cultural methods of management used are either ineffective or toxic to the environment. Plant secondary metabolites; therefore, pose a possible alternative because they are environmentally friendly and have minimal effect on non-target organisms. This study screened phytochemical compounds of two plants; Tithonia diversifolia (Hemsl.) A. Gray and Kigelia africana (Lam.) Benth and assessed their potency in controlling plant fungal pathogen F. oxysporum, a causal agent of Fusarium wilt disease in tomatoes. Leaf extractsof T. diversifolia and fruit extract of K. africana were concentrated in water and screened for phytochemical contents using standard procedures. Concentrations used were25g/L,50g/Land100g/Ltosockthedisc. Fusarium oxysporum was isolated from infected soil using potato dextrose media, Antifungal activity was evaluated by measuring the zone of inhibition against the test organism. The results showed that the mean inhibitory zones were highest at 100g/l in both plants, although K. africana fruit extract portrayed the highest inhibitoryactivity compared to Tithonia africana. The effect of the plant extracts and the negative control was statistically significant (p<0.05). This study indicates that K. africana and T. diversifolia possess the antifungal activity and can be used as a broad- spectrum fungicide against F. oxysporum. These plant extracts may provide an effective measure for the management of Fusarium wilt of tomatoes that may form an integral part of integrated management and it also has prospect as an alternative to reliance only on fungicides.