FUNGITOXIC EFFECT OF ETHANOLIC AND AQUEOUS LEAF EXTRACTS OF AZADIRACHTA INDICA A. JUSS, OCIMUM GRATISSIMUM LINN AND BENLATE IN THE CONTROL OF POST-HARVEST FUNGAL DISEASES OF SOLANUM MELONGENA LINN (EGG PLANT), A RESEARCH PROJECT TOPIC ON PLANT SCIENCE
The fungitoxic properties of ethanolic and aqueous leaf extracts of Azadirachta indica and Ocimum gratissimumused for the control of post-harvest fungal diseases ofSolanum melongenawere tested in vitrowith benlate serving as the standard fungicide and water as the bank control. Three fungal species,Aspergillus niger, Rhizoctonia solani and Mucor ramosissimuswere isolated from diseased S. melongena fruits kept at room temperature on laboratory tops for10 days. The fruits started showing signs of decay after 4 days of exposure. Growth on the fruits at the sites of the rot suggested the presence of fungal pathogens. Isolation and culturing of these pathogens gave the identified species as the causal agents. Pathogenicity test confirmed them as the causal organisms of the fruit rot. The three pathogens were treated with both ethanol and aqueous leaf extracts of the two plants at concentrations ranging from 25 to 100% and benlate at concentrations between 2.5 and 10.0%. Various concentrations of the extracts were added to prepared Potato Dextrose Agar (PDA) media. The pathogens were inoculated separately into the PDA media and were incubated for eight days. Fungitoxic effects of these extracts on the mycelial growth of the pathogens were significant at P ≤ 0.05 for all treatments. The three pathogens were completely inhibited by the two plant extracts for both the aqueous and ethanolic extracts at 100% concentration. With respect to ethanolic extract, O. gratissimum was more efficient than A indica, but the reverse was the case with aqueous extracts. Ethanolic extracts were generally more effective than the aqueous extracts. Ethanolic leaf extract of O. gratissimum may be used to effectively control post-harvest fungal diseases of S. melongena.
Garden egg (Solanum melongena Linn) of the family Solanaceae (Obeng-Ofori et al., 2007) is a kind of fruit that is very important for man; as food, supplying some major nutrients, and as a source of bioactive ingredients militating against some diseases like diabetes mellitus and liver problems. It is also used for many other purposes among which are to achieve weight control within a short period, eliminate unnecessary salts in maintaining proper functioning of the heart, reduce the sugar content level in diabetics because of its low calorie and high fibre contents and reduce blood cholesterol (Aliyu, 2006). However, the damage caused by pests and microbes often constitute a great impediment to biomass productivity of this plant.