The effectiveness of plant essential oils on the growth of Botrytis cinerea, Fusarium sp and Clavibacter michiganensis subsp michiganensis

Oregano, thyme, dictamnus, marjoram, lavender, rosemary, sage and pennyroyal essential oils were tested for their effectiveness against Botrytis cinerea, Fusarium sp. (Fusarium solani var. coeruleum), and Clavibacter michiganensis subsp. michiganensis on artificial growth media. The chemical composition of the oils was determined by gas chromatography-mass spectrometry (GC-MS). The growth of Botrytis cinerea, Fusarium sp. and Clavibacter michiganensis subsp. michiganensis was completely inhibited by oregano, thyme, dictamnus and marjoram essential oils at relatively low concentrations (85-300 mug/ml). Thymol was the main component of oregano oil, while thyme, dictamnus, and marjoram oils were rich in carvacrol. Lavender, rosemary, sage, and permyroyal essential oils presented less inhibitory activity. The growth of the tested microorganisms was affected at concentrations up to 1000 mug/ml. Lavender oil was characterized by the high content of linalool and linalyl acetate, while eucalyptol was the main component of sage and rosemary oils. Pennyroyal oil was found rich of cis-menthone and pulegone. (C) 2002 Elsevier Science Ltd. All rights reserved.