Chemical composition and antifungal activity of Thymus algeriensis, Mentha pulegium, Mentha rotundifolia and Artemesia herba-alba essential oil against Biscogniauxia mediterranea, agent of cork oak charcoal canker in Tunisia
Abstract: Biscogniauxia mediterranea (De Not.) Kuntze associated with the decline of Quercus suber has been reported in many forests in many regions of the Mediterranean basin. This pathogen causes charcoal canker on the trunk. B. mediterranea was noted in Tunisian cork oak forests since 1967 causing damage mainly after a long drought period. At present, there are no effective means of controlling this pathogen and the need to define suitable measures in order to control its infections in forest has become a priority. In this regard, essential oils may be a good candidate, as they are in general considered minimum-risk pesticides. There is a lack of research on the use of essential oils in forest and in nursery. Therefore, the objective of this work is to evaluate in vitro the antifungal activity of the essential oil extracted from Thymus algeriensis, Mentha pulegium, M. rotundifolia and Artemesia herba-alba against B. mediterranea using the disk diffusion methods on PDA plates. The essential oils were tested at different concentrations. Sixteen compounds, representing 91.73% of the total essential oil, were identified by chromatography analysis from T. algeriensis. The principal constituent is α-pinene (26.11%). Twenty four compounds, representing 98.3% of the total essential oil, were identified from M. pulegium. The principal constituent is pulegone (62.24%). The essential oil of M. rotundifolia consists of 24 compounds representing 90.3% of the total compounds. The principal constituent is rotundifolone (65.33%). The essential oil of A. herba-alba consists of 21 compounds of the total essential oil. The principal constituent is β-thujone (30.05%). The pure essential oil of A. herba-alba showed a strong inhibitory effect on the mycelial growth of B. mediterranea by more than 60% comparing to T. algeriensis, M. pulegium and M. rotundifolia. The activities of the essential oil were associated to the major compound of oils. Our results may provide a basis for the development of new control strategies of B. mediterranea on Q. suber.