Comparative Efficacy of Aloe vera (Linn) and Aloe schweinfurthii (Baker) Powdered Leaf Extracts in the Control of Some Plant Fungal Pathogens

Abstract

Evaluation of the relative efficacy of powdered leaf extracts of Aloe vera (Linn) and Aloe schweinfurthii (Baker) in the control of some plant pathogens was undertaken in this work. Antimicrobial activities of the extracts obtained using cold water, hot water and ethanol were tested against four fungal spp., namely, Alternaria solani, Colletotrichum lindemuthianum, Sclerotium rolfsii and Trichophyton rubrum. The phytochemical screening of the leaf extracts of the two aloe species revealed the presence of bioactive compounds such as alkaloids, tannins, saponins, flavonoids, cardiac glycosides, phytates and oxalates. The extracts were observed to exhibit varying inhibitory effects on the selected fungi. Ethanolic extract of A. vera at 50 mg/ml and 100 mg/ml had the greatest impact on A. solani and C. lindemuthianum respectively. Similarly, cold water extract of A. schweinfurthii at 100 mg/ml was the most effective against S. rolfsii and T. rubrum. However, hot water extract of A. vera was least effective against C. lindemuthianum. Also, the efficacy of cold water extract of A. schweinfurthii at 50 mg/ml was very low against T. rubrum and A. solani. The hot water extract of A. schweinfurthii at 20 mg/ml also showed the least effect against S. rolfsii. Consequently, extracts from both Aloe species can be recommended in the management of the four fungal pathogens evaluated in this study. It is hoped that in no distant future, botanical fungicides would be developed from the two Aloe species.