The present study identified the chemical composition of oil extracts from the leaves of E. adenophorum (termed ‘oil extracts’) and evaluated their effect against P. myriotylum in vitro mycelial growth and mycelial weight as well as in vivo activity. Moreover, its synergistic effects where assessed when mixed with synthetic fungicides on P. myriotylum in vitro. As a result of this work, a preliminary explanation was suggested for the possible mode of action of E. adenophorum oil extracts against the mycelium growth of P. myriotylum.