This study was carried out during 2013 – 2014 years to determine essential oils properties of some wild medicinal plant species [(Quysum) Achillea fragrantissima, (Zoeitran) Thymus decussates, (Samwah) Cleome droserifolia and (Myrrh) Tanacetum sinaicum)] and their antifungal inhibitory effects on four pathogenic fungi namely Alternaria alternata, Aspergillus niger, Aspergillus flavus and Fusarium oxysporum. The main components of Thymus decussates and Achillea fragrantissima oils were Thymol, Terpine-4-ol and Linolool alcohol. But, Cleome droserifolia oil was contain (E)-3,7,11-trimethyl , Cartotol , β -Eudesmol and Z-Myroxide. As for Tanacetum sinaicum oil, its main components were Thymol, Trans – Thujone and Trans-chrysanthenyl acetate. The antifungal activities of these oils at concentrations of 0.1, 1.3, 1.6 and 2.0 mg/ ml were investigated using disc-diffusion method. Also, the minimum inhibitory concentrations (MIC) of the 4 essential oils were determined by subjecting the tested fungi to different tested essential oils at concentrations ranging between 0.2 to 2.3 mg/ ml (21 treatments for each plant).
The low concentration (0.1 mg/ ml) of all tested essential oils did not show any inhibitory effects on the four examined fungi. At the same time, Thymus decussates essential oil at 2.0 mg/ ml followed by Achillea fragrantissima oil at 2.0 mg/ ml were the superior in their suppression on fungal activity of all tested fungi.
Cleome droserifolia essential oil had the highest inhibition on growth of Aternaria alternate, Aspergillus niger and Aspergillus flavns fungi when it used at concentration 2.0 mg/ ml. While, it inhibited Fusarium oxysporum growth when it used at 1.3 mg/ ml level. For Tanacetum sinaicum essential oil, its inhibitory effect on all examined fungi was exhibited only when it used at moderate concentration of 1.3 mg/ ml.
Respecting fungi sensitivity to essential oils, the minimum inhibitory concentrations test reveal that Aternaria alternata fungus followed by Aspergillus niger were the sensitive fungi to various tested essential oils. But, Aspergillus flavns was the resistant one and Fusarium oxysporum had moderate degree in its resistance against the tested essential oils.
In conclusion: results of such research confirm possibility of using the extracted natural essential oils of some medicinal plants as substitutes to chemical fungicides for overcoming the pathogenic fungi hazard effects.
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