Chemical Composition and Antibacterial Activity of two Essential Oils of rosemary Against Erwiniaamylovora, the causal agent fire blight

To deal with resistance and toxicity problems caused by the massive use of chemical synthetic substances, and with the fact that regulation organizations are questioning about the use of antibiotics in agriculture, it is particularly urgent to find alternatives to provide efficient protection of crops against plant diseases. Therefore, this study aimed at evaluating the antibacterial activity of essential oils (EOs) extracted of two species of Rosmary (Rosmarinus officinalis and Rosmarinus eriocalyx) against Erwinia amylovora, the causal agent of fire blight disease. The extraction was carried out by water distillation Clevenger’s type apparatus. The yields of extracted EOs are about 1.6% and 2.1% respectively for R.officinalis and R. eriocalyx. The chemical compositions of EOs were investigated by using a gas chromatography/mass spectrometry (GC-MS) and showed that EO of R.officinalis was characterized by the presence of 1,8-cineole (40,43%), alpha-pinene (8,84%), and camphor (22,23%) as the main chemical components. The EO of R.eriocalyx is formed by1,8-cineole (45,01%), alpha-pinene (11,29%) and camphor (18,43%). The in vitro antibacterial activity against E.amylovora was evaluated using the method of aromatogram. The results revealed that EO of R.officinalis is the most active against E. amylovora.