Fumigant Antifungal Activity ofCorymbia citriodoraandCymbopogon nardusEssential Oils and Citronellal against Three Fungal Species

Abstract

Corymbia citriodoraandCymbopogon nardusessential oils samples were analyzed by GC and GC-MS and their qualitative and quantitative compositions established. The main component of essential oils ofC. citriodoraandC. narduswas citronellal, at 61.78% and 36.6%, respectively. The essential oils and citronellal were tested for their fumigant antifungal activity againstPyricularia(Magnaporthe)grisea,Aspergillusspp., andColletotrichum musae. The minimum inhibitory concentration (MIC) ranged from 100 to 200 ppm for the essential oils and 25 to 50 mg·mL−1for citronellal. The contact assay using the essential oils and citronellal showed growth inhibition of the three fungal species. However, a concentration of 1.47 mg·mL−1only reduced the inhibition ofAspergillusgrowth to 90% at 14 days of exposure. For the fumigant assay, 0.05, 0.11, and 0.23 mg·mL−1of essential oils and citronellal drastically affected growth ofP. grisea, Aspergillusspp., andC. musae. Harmful effects on the sporulation and germination of the three fungi were seen, and there was complete inhibition at 0.15 mg·mL−1with both oils and citronellal. This showed that the crude component of essential oils ofC. citriodoraandC. nardusmarkedly suppressed spore production, germination, and growth inhibition ofP. grisea,Aspergillusspp., andColletotrichum musae.