Antibacterial activities of the essential oils from medicinal plants against the growth of Clavibacter michiganensis subsp. michiganensis

In the present study antibacterial activities of essential oils obtained from aerial parts of aromatic plants such as thyme (Thymbra spicata subsp. spicata), oregano (Origanum syriacum var. bevanii), mint (Mentha spicata), and lavender (Lavandula stoechas subsp. stoechas) were investigated against the seedborne plant pathogenic bacterium, Clavibacter michiganensis subsp. michiganensis (Cmm ICP7200), the causal agent of bacterial canker or wilt of tomato. By using the paper disc diffusion assay, all essential oils have shown antibacterial activity. Essential oils used in the paper disc diffusion assay varied in their antibacterial activity. Essential oil from thyme was the most effective in inhibiting the growth of Cmm, followed by those obtained from oregano and lavender. By using the micro agar broth dilution assay, the minimum bactericidal concentrations of the essential oil of thyme, oregano, ment and lavender were 10, 10, 25 and 50 µg/ml, respectively.