Extraction of essential oil from inflorescences of Dysphania ambrosioides and its activity against Botrytis cinerea

Essential oils are natural complex substances biosynthesized by plants, and many of them have antimicrobial properties. Dysphania ambrosioides is a medicinal plant traditionally used as an anthelmintic medicine. In this study, the antifungal activity of D. ambrosioides essential oil was tested against Botrytis cinerea, which is responsible for large economic losses in the post-harvest of roses. Inflorescences of D. ambrosioides yielded 1.3 mg.g-1 of essential oil in fresh material, corresponding to a content of 0.13%. Gas chromatography coupled with mass spectrometry (GC-MS) revealed 11 compounds in the essential oil with ascaridol and O-cymene corresponding to 80% of the total. The essential oil reduced B. cinerea mycelial growth by approximately 60% and spores germination by 51% at the concentration of 1000 ppm. However, no apparent morphological changes were observed in scanning electron microscopy analyzes. The essential oil was not able to reduce mycelial growth on rose petals and caused a color change in the petals 24 h after the treatment. Although the essential oil has little potential to control B. cinerea on roses due to the color change it causes, its activity on mycelial growth and spores germination could be exploited in other pathosystems.   Key words: Rosa hybrida, grey mold, chenopodium ambrosioides.