Sesquiterpenes from the conifer root rot pathogen Heterobasidion occidentale

► Six sesquiterpenes were identified from the basidiomycete Heterobasidion occidentale. ► The sesquiterpenes were suggested to be involved in the biosynthesis of fomannosin. ► The biosynthesis was suggested to include one Baeyer-Villiger monooxygenase. ► Four of the sesquiterpenes were antifungal and phytotoxic and one was antibacterial.