Defensive roles of terpenoid mixtures in conifers

Significance of constitutive and induced terpenoid defences in conifer resistance is briefly presented. Discussion is focused on monoterpenoids and emphasis is on terpenoid mixtures which appear to be more effective in chemical defences. Better knowledge of the mechanism of action of individual ter- penes and about the combined (additive and synergistic) effects of compounds, will have important implications for forest and agricultural management of pests and pathogens.