Screening and Evaluation of Essential Oils from Mediterranean Aromatic Plants against the Mushroom Cobweb Disease, Cladobotryum mycophilum

The main aim of this study was to evaluate the use of essential oils (EOs) as an alternative to synthetic fungicides used in the control of cobweb disease of button mushroom (Agaricus bisporus) caused by Cladobotryum mycophilum. The EOs used were obtained by hydrodistillation from five Mediterranean aromatic species (Lavandula x intermedia, Salvia lavandulifolia, Satureja montana, Thymus mastichina, and Thymus vulgaris), analyzed by gas chromatography, and tested in vitro for their antifungal activity against C. mycophilum. In vitro bioassays showed that the EOs obtained from T. vulgaris and S. montana (ED50 = 35.5 and 42.8 mg L-1, respectively) were the most effective EOs for inhibiting the mycelial growth of C. mycophilum, and were also the most selective EOs between C. mycophilum and A. bisporus. The in vivo efficacy of T. vulgaris and S. montana EOs at two different concentrations (0.5 and 1%) were evaluated in two mushroom growing trials with C. mycophilum inoculation. The treatments involving T. vulgaris and S. montana EOs at the higher dose (1% concentration) were as effective as fungicide treatment. The effect of these EOs on mushroom productivity was tested in a mushroom cropping trial without inoculation. They had a strong fungitoxic effect at the first flush. However, a compensatory effect was observed by the end of the crop cycle and no differences were observed in biological efficiency between treatments. The main compounds found were carvacrol and p-cymene for S. montana, and p-cymene and thymol for T. vulgaris. These results suggest that T. vulgaris and S. montana EOs may be useful products to manage cobweb disease if used as part of an integrated pest management (IPM) program.