Adeniyi et al.: IJOTAFS 4(1): 2010
MATERIALS AND METHODS
Fresh leaves of neem (Azadirachta indica) were collected and washed thoroughly in water. The
leaves were air-dried on laboratory bench at room temperature and ground into powder using
mortar and pestle. The hot water extraction of the leaves was achieved by infusing 5.0, 10.0, 15.0,
20.0 and 25.0 g of A. indica powder into 100 ml of sterile distilled water in a 250 ml conical flask in
water bath at 50OC for 2 hours. This was allowed to cool and the crude extracts obtained from the
infusion by filtration through sterile muslin cloth to give concentration of 5, 10, 15, 20 and 25%
respectively. The ethanolic extraction of the neem leaf was prepared according to the method of
(Ayoola et al., 2008).
Potato dextrose agar(PDA) was prepared routinely and 10% lactic acid added to suppress bacteria
growth. The Fusarium sp was isolated from the storage rot development in kolanut using the
method of (Hina and Arshad, 2007), with some modifications and maintained on Agar PDA
The effect of neem leaf extract was tested on the mycelial growth of the isolated fungus. Five ml of
each of the percent concentrations of the neem extract were mixed thoroughly with about 20 ml of
PDA separately in Petri dishes and were allowed to solidify. An inoculum disc of 4 mm diameter of
the pure culture of the isolate was placed on the potato dextrose extract agar in each Petri dish
and replicated thrice. Five ml of sterile water in place of the extracts serve as control. The plates
were incubated at ambient temperature and observations were recorded at regular interval.
The toxicity of the crude and ethanolic extracts was determined against the pathogen. The percent
inhibition of mycelial growth over control was calculated using the formula:
Percentage of inhibition = 1 –
Diameter of treated colony
Diameter of control colony
RESULTS AND DISCUSSION
The aqueous and ethanolic extracts of the leaf of A. indica showed varying degrees of inhibition on
Fusarium sp by suppressing their mycelial growth. The degree of inhibition in both methods of
extraction increased with the increase in the concentration of leaf extract, but the control showed
The mycelial growth inhibition by the aqueous leaf extract ranged from 14 – 82% at 20 and 25%
concentration, while that of the ethanolic extract was from 30 – 82% at the same extract
concentrations (Table 1).
Table 1: Inhibition of Aqueous and Ethanolic extracts on mycelial growth of Fusarium spp.
Leaf extracts concentration
Water extracts (%)
Ethanolic extracts (%)
Mean followed by the same letter in the same column are not significantly different (P=0.05)
The ethanolic extract tested was shown to be more effective as it was seen to have greater percent
of inhibition on the fungus compared to the aqueous extract. However, both exhibit equal
inhibitions of the mycelial growth at 20 and 25% extracts concentrations. The ethanolic extracts
again had higher inhibition of Fusarium spp. at lower concentrations compared to aqueous extracts.
Azadirachta indica has been reported as effective against Fusarium oxysporum causing wilt disease
of Solanum melogena. A. indica was effective in reducing the mycelial growth of F. oxysporum at
50% concentration of plant extracts (Siva et al., 2008). The present results are also in agreement
with the earlier report by Govindachariu et al. (1999) that A. indica showed high antifungal activity
against spore germination of F. oxysporum and Colletotrichum lindemuthianum. Extracts of Tridax
procumbens and Capparis deciduas were also reported to totally inhibit spore germination of F.
oxysporum (Bindu and Padma, 2009). The aqueous extracts of A. inidica significantly suppressed
the biomass of Macrophomina phaseolina. There was a gradual decrease in fungal biomass with
the increase in extract concentration (Hina and Arshad, 2007).
Adeniyi et al.: IJOTAFS 4(1): 2010
Azadirachta indica as shown in this experiment is effective in inhibiting the mycelial growth of
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