Abstract: There is a very limited information about plants with antifungal properties acting on roots infected by fungi. The aqueous extracts of fifteen plant species were tested against onion (Allium cepa) white rot fungus Sclerotium cepivorum that was grown in potato dextrose agar culture. Each extract presented a fungicidal effect, at a concentration of 5%, when applied on allspice (Pimenta dioica) and clove (Syzygium aromaticum). Only clove extract retained its effect at a concentration of 1%, while allspice lost it at 3%. Cinnamon (Cinnamomum zeylanicum) and yambean (Pachyrhizus erosus) extracts produced total inhibition of sclerotial production besides a poor mycelial growth. Different types of interactions were present when the extracts were mixed: all combinations presented a lost of fungicidal effect (antagonistic effect), including allspice extract; a retained fungicidal effect (single fungicidal effect) occurred in most clove mixtures and in the combination of clove and black pepper (Piper nigrum) the retained fungicidal effect was even below the minimal lethal dose (synergistic effect). The combination of extracts showed that the effect of each plant extract could be modified by the reactions of the complex mixture of plant compounds.