36 POST-HARVEST CONTROL OF SOFT ROT DISEASE OF COCOYAM CAUSED BY Sclerotium rolfsi USING LOCAL BITTER LEAF EXTRACT AUSTIN A. OKWELLE GEORGE, T. S. ABSTRACT The effectiveness of Bitter leaf (Vernonia amygdalina) extract in the control of Sclerotium rolfsi, the fungi causing post-harvest soft rot disease of cocoyam was investigated. Pure cultures of Sclerotium rolfsi isolated from infected cocoyam corm was inoculated into Potato Dextrose Agar plates containing different concentrations (30, 60, 100%) of bitter leaf extract. Fungitoxicity of the extract was determined in vitro by monitoring percentage colony inhibition (PCI) of mycelial extension growth of the fungus over a seven (7) day period. Data obtained was analysed using Analysis of Variance (ANOVA) and the Least Significant Differences (LSD) at 5% probability level (P = 0.05) to separate the means. The test showed positive fungicidal activity, at only 30% extract concentration level. INTRODUCTION Cocoyam, Colocasia esculanta, is a short swollen underground corm, similar to a tuber. The plant is widely distributed in tropical and temperate regions. It is rich in complex starch, dietary fibre, vitamin B6 and magnesium. Cocoyam flour has the added advantage of being very digestible in baby foods (Ogbeche et al, 1997). A great majority of pathogenic fungi causes infectious diseases in plants especially during storage. Post-harvest soft rot disease of cocoyam is caused by Sclerotium rolfsi, belonging to the subdivision Basidiomycota. The fungi causes deterioration of cocoyam corm in storage which affects availability of the crop for the next planting season. So it seems desirable to investigate the possibility of developing good control measures that will enhance the shelf-life of the crop. Austin A. Okwelle and George, T. S. are Lecturers in the Department of Biology, Rivers State College of Education, Port Harcourt, Nigeria. International Journal of Food and Agricultural Research, Vol. 5, No 1 & 2 © 2008 by The Development Universal Consortia. All Rights Reserved