Soybean is affected by a wide range of diseases, many of which are seed-borne. In vitro and in vivo studies were conducted on the control of Fusarium oxysporium the causal pathogen of soybean seed rot using three plant leaf extracts. Laboratory experiments were conducted with aqueous extracts of air dried leaves of Ficus exasperata, Jatropha curcas, and Mangifera indica and a synthetic fungicide Mancozeb. Using the poisoned food technique, various concentrations (20, 40, and 60%) of the leaf extracts and Mancozeb (0.002%) utilized inhibited the mycelial growth of the pathogens in vitro. Effects of Mancozeb comparative to the plant extracts were determined. Even though all the extracts showed varying degrees of antifungal efficacy, 60% concentration of F. exasperata had the highest level of inhibition (64.52%) on the mycelial growth of the pathogen and was significantly different (P≤0.05) from Mancozeb (83.86%) after 3 days. Extracts of J. curcas and M. indica showed a lower inhibition level ranging from 54.80% to 18.56% and 54% to 22.59% respectively, which were significantly lower in comparison to Mancozeb (P≤0.05). Inhibition of fungal growth increased with a corresponding increase in extract concentration and days. The plant leaf extracts effectively inhibited mycelial growth of the pathogen in vitro after 3 days. The efficacy of seed treatments against seedborne F. oxysporium were evaluated under greenhouse conditions at 40 and 60% concentrations. The result indicated that seeds of various soybean varieties (TGX1448, TGX1987- 10F, TGX 1988-5F) treated with 60% concentration of F. exasperata performed better than the others and improved seed germination: 33.33% in TGX1448 and TGX1987-10F and 26.67% in TGX 1988-5F. The number of leaves was 4.33, 5.0 and 3.67 in TGX1448, TGX1987-10F, TGX 1988-5F respectively; while stem length was 18.33cm, 18.67cm, 15.00cm respectively, in the above order. However, the results were lower and statistically different (P≤0.05) from Mancozeb and the uninoculated control. The results obtained in this study confirmed that Jathropha curcas, Ficus exasperata, and Mangifera indica possess potential inhibitory effect on Fusarium oxysporium, one of the causal agents of Soybean seed rot and seedling blight.

Keywords : Soybean, Mancozeb, Seed-borne fungi, In vitro, In vivo