Abstract The fungitoxic activity against Botrytis cinerea and Phytophthora citrophthora of 19 essential oils distilled from Moroccan medicinal plants is reported. The results of the in vitro trials showed strong activity by the oil of Chrysanthemum viscidehirtum, which completely inhibited the growth of the two fungi at a concentration of 150 ppm. The fungitoxic activity was compared with procymidone for Botrytis cinerea and propamocarbe (HCl) for Phytophthora citrophthora. Gas chromatographic analysis of the oil from C. viscidehirtum aerial parts showed that it consisted mainly of Î²-farnesene (25.0%), limonene (21.8%) and oxygenated sesquiterpenes (7.4%). Analysis of Aloysia triphylla oil revealed that its main components were limonene (10.1%), nerol (11.9%), geraniol (15.4%) and spathulenol (13.1%).