Cymbopogon citratus L. essential oil as a potential antifungal agent against key weed moulds of Pleurotus spp. spawns

The essential oil of Cymbopogon citratus L. (250-1500 p.p.m.) was tested in vitro for antifungal activity against seven Pleurotus spp. spawn-contaminating fungi, viz. Aspergillus flavus, A. fumigatus, A. niger, Alternaria alternata, Penicillium citrinum, Curvularia funata and Trichoderma harzianum. Oil-enrichment resulted in significant (p < 0.05) reduction of growth for the pathogens examined. Fungal spore production inhibited up to 80% at 250 p.p.m. of the oil except for C. lunata, which was inhibited by only 30%. In the higher oil concentration (1500 p.p.m.) employed, fungal sporulation was completely retarded. Lemongrass oil reduces spore germination in A. flavus, A. fumigatus, A. alternata, P. citrinum and T. harzianum, with the effects dependent on oil concentration. However, lemongrass oil at 250 p.p.m. accelerated spore germination for A. niger and P. citrinum. Indeed, further increase in oil concentration shows complete inhibition. Among the pathogens, C. funata was found to be most resistant strain, while A. niger was the most sensitive strain against lemongrass oil. Copyright (c) 2007 John Wiley & Sons, Ltd.