Cotton is one of the most important industrial crops produced in large areas in Turkey.
Cotton bacterial blight disease agent Xanthomonas citri subsp. malvacearum (Syn.
Xanthomonas axonopodis pv. malvacearum) is a seed-borne pathogen. Plant essential
oils are natural antimicrobial compounds that have the potential to be used as an
alternative to chemical control of seed-borne phytopathogens. In this study, the
bacterial pathogen X. citri subsp. malvacearum was isolated from cotton plants
showing typical disease symptoms during the 2023 growing season in Diyarbakır
provinces and the antibacterial effect of essential oils obtained from 11 different
medicinal plants (Thymus serpyllum, Origanum syriacum, Thymus syriacus, Origanum
onites, Cistus laden, Salvia aramiensis, Laurus nobilis, Hypericum perforatum,
Rosmarinus officinalis, Origanum majorana and Thymbra spicata) were determined by
disk diffusion method. Bacterial isolates, obtained from cotton plants showing typical
disease symptoms, were identified as X. citri subsp. malvacearum by biochemical and
pathogenicity tests and also MALDI-TOF analysis. The essential oils used in the study
showed antibacterial activity against the bacterial agent by forming an inhibition zone
with a diameter of 6.33-46.33 mm in the nutrient media. T. serpyllum and T. spicata
(43.33 mm), O. syriacum (43.00 mm), T. syriacus (38.33 mm) and O. onites (37.3 mm),
were identified as the most effective essential oils respectively. The essential oils of H.
perforatum (9.67 mm), L. nobilis (9.0 mm) and S. aramiensis (6.33 mm) showed
relatively lower antibacterial activity against the disease agent. The results showed
that essential oils of Thymus spp., Thymbra spp. and Origanum spp. have the potential
to be used as an alternative to chemical control against seed-borne bacterial plant
pathogens.