Chemical Composition and Antifungal Property of Eucalyptus camaldulensis Leaf Oils from Thailand

The present study was performed to evaluate antifungal activities of leaf essential oils from Eucalyptus camaldulensis Dehnh. originating from Thailand against 9 fungal strains. The leaf samples were collected from 3 different clones. The fungi examined in this study were (1) household molds: Aspergillus niger, Cladosporium cladosporioides, Chaetomium globosum and Penicillium citrinum, (2) wood rot fungi: Fomitopsis palustris and Trametes versicolor, (3) plant pathogenic fungi: Fusarium oxysporum, Thanatephorus cucumeris and Rhizopus oryzae. The results revealed that E. camaldulensis leaf oils provided 100% inhibition of the mycelial growth of T. cucumeris (5 mg/mL), and C. globosum (10 mg/mL). No inhibition effect was observed against R. oryzae even at the concentration of 10 mg/mL. A medium to low inhibitory activities against the mycelial growth of the six other fungi were found. The essential oils of E. camaldulensis leaf have potency as an antimicrobial agent especially against seedling blight pathogens and it could also act as moderate agents against household molds and wood rot fungi. Therefore, even if they need relatively higher concentration for the controlling agents, they deserve as the alternatives to hazardous synthetic fungicides from the ecological viewpoints.