PRELIMINARY EVALUATION OF In vitro SECONDARY METABOLITES OF Sclerotium cepivorum, THE CAUSAL AGENT OF ONION WHITE ROT

Culture filtrates and organic solvent extracts of Sclerotium cepivorum liquid cultures were evaluated for their antifungal activities against the same fungus. Filtrates at 50% taken from 30 to 45-day-old cultures have reduced S. cepivorum growth by 51.9%. This treatment has also caused a reduction in the number of sclerotia by 98.6%. No sclerotial germination was observed on the media amended with the culture filtrates at all concentrations tested (10, 25 and 50%),.Among all organic solvent extracts, methanol extract was the strongest growth inhibitor against the fungal pathogen; it inhibited S. cepivorum growth by 82.2, 93.3, and 93.6% when used at concentrations of 400, 800, and 1200 ppm, respectively. At the same concentrations, ethyl acetate extract exhibited high inhibition to the fungal growth i.e., 85.56, 88.89, and 90.56%, respectively, while chloroform extract was the least effective in this regard causing 71.11% mycelial growth inhibition when used at concentrations of either 800 or 1200 ppm. All organic-solvent extracts completely suppressed the formation and germination of sclerotia at all concentrations. Further studies are needed to isolate different bioactive compounds from secondary metabolites of S. cepivorum.