Yield, phytochemical characterization and anti- Allorhizobium vitis activity of essential oils from four Eucalyptus species growing in Morocco

This study aims to investigate the yield, chemical composition and inhibitory effect of four essential oils of eucalyptus collected from Morocco on the pathogenic Allorhizobium vitis S4 causal agent of the crown gall of grapevine. The identification of the constituents of essential oils was performed by GC-MS analysis and the antibacterial activity was evaluated using an aromatogram test. The yield of different samples of eucalyptus ranged from 2-4.5%. The results of chemical compounds analysis show that the major compounds of eucalyptus essential oils are, 1,8-Cineol (Eucalyptol) (65.55-78.11%), α-Pinene (3-15.21%), 2-β-Pinene (2.33-5.27%) and p-Cymene (0.79-11.51%). All eucalyptus essential oil exhibits an antibacterial activity in vitro against Allorhizobium vitis strain S4 with a percentage of inhibition and minimal inhibitory concentration values in the range of 13.67-20.50 % and 20-40 mg/mL, respectively.