Antifungal activity of aqueous stem bark extract of Pterocarpus erinaceous and Erythrophelum suaveolens (Guill &Perri) Brenan on sweet potato fungi

Abstract

Sweet potato is an important source of food and income for communities in Benue State North Central Nigeria. The plant is prone to attack by leaf spot fungi which are capable of partially or totally killing the plant. The antifungal activity of three concentrations of aqueous extract of Erythropleum suaveolens and Pterocarpus erinaceous were used in the management of sweet potato leaf spot fungi viz: Macrophomina phaseolina (Tassi) Goid, Aspergillus flavus and Fusarium verticolliodes. Three concentrations of the stem bark extracts of Erythrophelum suaveolens and Pterocarpus erinaceous at 10, 20 and 30% w/v were used in the in-vitro management of leaf spot pathogen of sweet potato. The experiment was a 2×3 factorial laid out in a Completely Randomised Design (CRD). The hot water aqueous extracts of the stem bark of E. suaveolens exhibited fungitoxicity against all three test fungi at 3 and 7 Days After Inoculation (DAI). The mycelia growth of test fungi after three days was significantly lower in Potato Dextrose Agar (PDA) amended with the aqueous extracts of E. suaveolens compared with the aqueous extracts of P. erinaceous. Generally, the results indicated that the test fungi were most sensitive to P. erinaceous at 20% w/v while E. suaveolens recorded the least potency at 20% w/v. The efficacy of stem bark extracts of P. Erinaceous at 10% w/v increased at the seventh day thereby reducing mycelia growth of A. flavus but stimulated the mycelia growth of M. phaseolina. The study demonstrated fungi toxicity of the aqueous crude extract of the stem bark of E. suaveolens against sweet potato fungi.