Antifungal Efficacy of Leaf Extracts of Neem, Bitterleaf and Their Mixture Against Ustilago scitamineum

Abstract

This study was aimed at evaluating the antifungal activity of leaf extracts of neem, bitterleaf and their mixture against Ustilago scitamineum (Syd.), the pathogen of sugarcane smut disease. A suspension of mancozeb, carbendazim+maneb, matalaxy l+ carboxin + flurathiocarb, pyroquilon, benomyl, chlothalonil and flutriafol are effective as a dip in controlling the disease. However, the listed synthetic fungicides led to emergence of resistant strains of the pathogen and also cause environmental pollution. Hot water treatment of the cane setts at 52º C for 30 minutes before planting is also effective, but this can cause serious injuries on sugarcane farmers if not carefully practiced. Pour Plate method was used to determine antifungal effect of 10, 20 and 30 g/ 100 ml concentrations of aqueous and ethanolic leaf extracts of neem, bitterleaf and their mixture on radial growth of U. scitamineum for 6 days. The tested leaf extracts inhibited mycelial growth of U. scitamineum in vitro, with the ethanolic leaf extracts being more potent at some of the concentrations tested in this study. In conclusion, gradient of antifungal efficacy of the tested leaf extracts against U. scitamineum was: mixed leaf extracts > neem leaf extracts >bitterleaf leaf extracts at all the concentrations used.