Antimicrobial Activity of Some Essential Oils Against Agricultural Phytopathogenic Fungi and Bacteria
Essential oils (EOs) are gaining attention as eco-friendly alternatives to synthetic pesticides for the management of phytopathogenic fungi and bacteria. In this study the in vivo antimicrobial activities of juniper (Juniperus communis), rosemary (Rosmarinus officinalis), cumin (Cuminum cyminum), sage (Salvia officinalis), dill (Anethum graveolens) and oregano (Origanum onites) essential oils were investigated against 2 phytopathogenic fungi (Fusarium solani and Rhizoctonia solani) and 2 bacteria species (Erwinia caratovora and Streptomyces scabies) causing high economic losses in potato. Experiment was conducted in a completely randomized factorial design with three replicates at greenhouse conditions. EOs were sprayed at 0, 100, 250, 500 and 1000 µl/l concentrations to aerial parts of potato plants with a manually operated sprayer for 3 times at 15 days intervals starting from the 4-5 true leaf. The application of EOs showed low to high efficiency in suppressing fungal and bacterial diseases of potato tubers and the effectiveness of EOs applications varied depending on the application dose. R. solani infection severity, which was over 17% in the control, decreased to 4.5% with the application of 500 ppm and above sage essential oil, and F. solani infection severity, which was over 19% in the control, decreased to 8.4% and 3.6% at 1000 ppm juniper and oregano essential oil applications, respectively. Oregano, dill and cumin essential oils showed higher antibacterial activity than other essential oils. E. carotovora infection severity, which was above 16% in the control, decreased to 3.3%, 5.0% and 5.0% with the applications of oregano, dill and cumin essential oil at a dose of 1000 ppm, respectively. The highest antibacterial activity on S. scabies infection severity was again observed at 1000 ppm oregano essential oil. It has been concluded that the phytopathogens discussed in the research can be suppressed by leaf application of essential oils on the potato plant and that these applications can make a significant contribution to the sustainability of agricultural production.