Antifungal activity of Moroccan plants against citrus fruit pathogens

The aim of this study was to find an alternative to the chemical fungicides currently used in the control of postharvest citrus fruit diseases. Here we screened twenty-one medicinal and aromatic plants used in southern Moroccan traditional medicine for their activity against Penicillium digitatum, Penicillium italicum and Geotrichum candidum. The antifungal efficacy of powders, essential oils and solvent extracts of these plants was tested in vitro by using the agar plates method. Our results show that among the 21 plants tested, the powders of Thymus leptobotrys, Cistus villosus and Peganum harmala plants totally inhibited the growth of all three pathogens. Furthermore, the powder of the Eucalyptus globulus plant totally inhibited the mycelial growth of both G. candidum and P. digitatum, whereas the powders of Juglans regia and Myrtus communis plants completely inhibited the mycelial growth of G. candidum, and the powder of the Arenaria rubra plant totally inhibited the growth of the P. digitatum fungus. The essential oils, as well as the methanolic and chloroformic extracts of plants with the highest antifungal activity, were tested against the mycelial growth of the three pathogens. The results indicate that only the essential oils and the chloroformic extract of the T. leptobotrys plant totally inhibited the three pathogens. These results demonstrate that plant-derived products have a high potential to control fungal diseases of citrus fruits. Such biopesticides therefore represent a sustainable alternative to the use of chemical pesticides.