Antibacterial effect of essential oil of Thymbra spicata L. var. spicata on some plant pathogenic bacteria

Antimicrobial activity of essential oil of Thymbra spicata L. var. spicata was investigated against some economically important plant pathogenic bacte ria including Erwinia amylovora, Erwinia carotovora pv. carotovora, Claviba cter michiganensis subsp. michigenensis, Pseudomonas syringae pv. syringae, Agrobacterium tumefaciens and Xanthomonas axonopodis pv. vesicatoria. Both contact and volatile phase effects of different doses of the essential oil were determined by using two different methods in vitro. Minimum Bacterici dal Concentrations (MBC) of the essential oil for E. amylovora, E. c. carot ovora, C. m. michigenensis, P. s. syringae, A. tumefaciens and X, a. vesica toria in the determination of the contact effect were 276, 413, 405, 344, 3 28 and 323 mg/ml, respectively. MBCs of the volatile phase of the essential oil for E. amylovora, E, c. carotovora, C. m. michigenensis, P. s. syringa e, A. tumefacians and X. a. vesicatoria were 51, 563, 91, 684, 98 and 41 mg /ml air, respectively. With exception to E, c. carotovora and P. s, syringa e, the volatile phase oil was found to be more toxic to the test bacteria.