Investigation of in vitro effects of medicinal and aromatic plants on some phytopathogens

In agriculture, diseases and pests cause crop losses, and the long-term use of synthetic pesticides leads to the development of resistance to pathogens. Medicinal and aromatic plants are important resources in many fields, and various substances obtained from plants stand out as safe alternatives to pesticides. In this thesis, it was aimed to investigate the in vitro effects of extracts obtained from various medicinal and aromatic plants on important plant pathogens. The phenolic constituents, antioxidant properties, phytonutrients, and biochemical content of Hypericum perforatum, S. rosmarinus, Mentha pulegium, Salvia officinalis, Thymus vulgaris, and Lavandula angustifolia were evaluated. The effects of the extracts of these plants at different concentrations in methanol and hexane on Fusarium oxysporum, Pestalotiopsis sp., and Clavibacter michiganensis phytopathogens were investigated. The highest amount of total phenolic compounds was determined in Salvia officinalis plants, while the highest activity in terms of DPPH scavenging effect was determined in methanolic extracts of S. rosmarinus plants, with 88.099% at 5 mg/L concentration. In terms of antifungal effects, hexane and methanol extracts of Salvia officinalis at different concentrations were effective against Pestalotiopsis sp.