Efficacy of Ocimum gratissimum and Vernonia amygdalina leaves of control of pathogenic fungi in Citrus Sinensis, Solanum lycopersicum and Carica papaya in Relief Market in Owerri Municipal

Abstract

This study was to evaluate the efficacy of Ocimum gratissimum and Vernonia amygdalina in control of pathogenic fungi in Citrus sinensis, Solanum lycopersicum and Carica papaya obtained in Owerri municipal, Imo state. Some microbes deteriorate fruits thereby reducing their nutritional and economic values. In order to prevent fruit loses, some synthetic and antimicrobial chemicals have been formulated and applied to prevent or treat these microbes. Sometimes, these chemicals may be harmful to both man and the environment. This study was aimed at investigating the efficacy of ethanol scent leaf and bitter leaf extracts in controlling fungal pathogens associated with the post harvest rot of sweet orange, tomato and pawpaw. The study was carried out at the Department of Plant Science and Biotechnology Laboratory, Imo State University, Owerri. 10 samples of each fruit with signs and symptoms of rot were collected from Relief market in Owerri Municipal and transported in aseptic bags to the laboratory. Fungi isolation was done using Potato Dextrose Agar (PDA). The fungi isolated were Aspergillus niger, Botryodiplodia theobromae, Botrytis cinerea, Fusarium oxysporium, Geotrichum candidum, Mucor racemosus and Penicillum citrinum. The percentage occurrence of the fungi showed G candidum (40%) as the highest occurred organism in orange, B. cinerea (14.29%) as the least occurred in pawpaw and A. niger and G. candidum as highest in tomato.  Plant extraction was done using maceration method. Antimicrobial effects of the plant extract were determined using well diffusing method for bacteria and food poisoning method for fungi. The antifungal effect of the plant extracts showed all the fungi isolates were strongly inhibited by them. Scent leaf extract has total inhibition on the growth of B. theobromae (100%), G. candidum (100%) and F. oxysporium (100%). Bitter leaf extract had least effect on A. niger  (38.89%) isolated from tomato. Synergistic effect revealed that the combination of the plant extracts has inhibitory effect on the fungi especially G. candidum  (100%), B. cinerea (100%), F. oxysporium (100%) and M. racemosus  (100%). This study showed the efficacy of these botanicals in inhibiting and control of fungi associated with rot of orange, pawpaw and tomato