Abstract. The importance of this study is to provide information for a future green solution to the toxic fungicides used in our days in crop and grain protection. Verticillium dahliae and Penicillium aurantiogriseum are very common in crop deposits and they are very hard to commbat even with synthetic fungicides. The aim of this research is to establish the minimum concentration of essential oil (EO) extracted from Origanum majorana L. which causes a fungistatic and fungicidal effect on Verticillium dahliae and Penicillium aurantiogriseum fungi. Previous research has shown the minimum inhibitory concentration of the Origanum majorana L. EO over Verticillium dahliae but not on Penicillium aurantiogriseum. Also we can say after reading more research papers that the chemical composition of the EO depends on the site of cultivation, climate conditions and the time of harvest. The tested medical plant,Origanum majorana L., was grown in a temperate climate zone in Timisoara, Romania (21013`E longitude, 45045` N latitude). At the time of harvest Origanum majorana L. was in the 4th year of vegetation. Identification of the species was confirmed by the department of Aromatic plants from USAMVB Timisoara. We obtained the EO from the dry herb using a volatile oil distilling Clevenger equipment. The chemical composition of the EO was determined using gas chromatography/mass spectrometry (GC/MS) analysis. The tests made in vitro on CYGA medium, with additional oil at 0.25 mg•L-1; 0.5 mg•L-1; 1 mg•L-1; 5 mg•L-1; 10 mg•L-1 and 15 mg•L-1and 20 mg•L-1 concentrations and inoculated with plugs harvested from a young mycelium, revealed a different reaction of the fungus depending on the oil concentration. The value of minimum inhibitory concentration (MIC) has been established after 14 days after verifying the restauration of hyphae and mycelium of fungi. The MIC value for Verticillium dahliae was 5 mg•L-1 Origanum majorana L. EO (essential oil). The MIC value for Penicillium aurantiogriseum was 1 mg•L-1 Origanum majorana L. EO (essential oil). The MFC(minimum fungicidal concentration) value for both Verticillium dahliae and Penicillium aurantiogriseum was 20 mg•L-1 Origanum majorana L. EO.

Key words. Origanum majorana L., mycelial growth inhibition, minimum fungicidal and fungistatic concentration.

Presentation: oral