Potency of ethanolic leaf extracts of Tithonia diversifolia (Hemsl.) A. Gray against the plant pathogen Alternaria brassicicola (Schwein) Wiltshire

Abstract Antifungal potency of Tithonia diversifolia leaf extracts against the plant pathogen Alternaria brassicicola has been investigated using three solvents: acetone, ethanol and methanol at different concentrations (60%, 80% an 99.9%). Out of the three solvent extracts used, ethanolic extract showed maximum inhibition zone at all concentrations studied, with the inhibition zones ranging from 0.4 to 1.9 mm. Acetone extract showed slight inhibition at 80% concentration as compared to its control whereas, methanolic extract showed slight inhibition at 100% concentration. Zone of inhibition by ethanol as control showed 0.3, 0.5 and 0.8 mm at 60%, 80% and 99.9% respectively, whereas, ethanol plus plant extract showed zone of inhibition measuring 0.4, 0.7 and 1.9 mm respectively, which is higher than their respective control concentrations. This indicates that ethanolic leaf extract of T. diversifolia has high potency against the test plant pathogen A. brassicicola. There was no inhibition zone observed for 60% acetone, indicating that 60% acetone leaf extract of T. diversifolia may not be effective against the test pathogen.