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