Abstract

Sweet potato (Iponmea batatas) ranks as the fifth most important food crop in developing countries. It is mainly affected by fungal and bacterial diseases, which reduces its yields, quality, storage life and cause economic losses. Synthetic fungicides usually used to prevent this spoilage are toxic to man, crop and environment. This necessitated the search for the use of biological fungicides from plants, safe, biodegradable, economically and environmentally friendly and available. This study was aimed to determine the efficacy of Murraya koenigii, Curcuma longa and Piper nigrum on sweet potato spoilage fungi. Samples were purchased from Bodija market and sweet potatoes were purchased from Oje and Bodija market, Ibadan, Oyo state, Nigeria and were brought aseptically in sterile polythene bags to the laboratory. Fungal pathogens were isolated and identified based on growth pattern, color of mycelia, microscopic examination of vegetative and reproductive structure of the fungi. Extraction of bioactive ingredients in the plants were performed using methanol and distilled water. The isolates include Aspergillus flavus and Aspergillus niger, and they were subjected to pathogenicity test, severity test. Aspergillus niger showed more virulence and was subjected to inhibition by the plant extracts. The extracts significantly (p<0.05) inhibited the pathogen growth and the most effective extracts against the fungal pathogens among the three is that of Murraya koenigii. The zones of inhibition ranges between 0.84 to 1.53, 0.48 to 1.64 and 0.62 to 1.65 cm for Black pepper, Curry leaf and Tumeric respectively, they hence can be used in the control of sweet potato fungal pathogens.