Study on antibacterial effects of some essential oils on bacterial blight of wheat under greenhouse conditions

Wheat bacterial blight disease caused by the bacterium Pseudomonas syringe pv. syringae (Pss) is one of the important diseases of wheat in the world. The expanding the diseases resistance to chemical compounds has led to the researches into the new antimicrobial agents finding.  Studies have shown that plant essential oils induce biological activity against plant pathogenic bacteria and can be used as an environment friendly and safe way to control the disease. These compounds have the least harm to the ecosystem and can be used as an alternative to toxic compounds for controlling plant diseases. This study was designed to evaluate the antimicrobial activity of the essential oils obtained from the aerial parts of Rosmarinus officinalis, Mentha spicata and Thymus daenensis, against Pss on wheat cultivars Pishtaz, Sirvan and Chamran under greenhouse conditions. In this study, all essential oil treatments significantly reduced the severity of wheat bacterial blight, especially on Pishtaz cultivar, and the percentage of necrotic area on the leaf 30 days after bacterial inoculation. The highest reduction in the severity of the disease was obtained by Mentha spicata and Thymus daenensi essential oils. The findings of the present study suggest that essential oils of Rosmarinus officinalis, Mentha spicata and Thymus daenensis are capable to be used as antimicrobial agents.