Botryosphaeria parva, Eutypa lata and Phomopsis viticola are ascomyceteous fungi responsible for severe
canker and dieback in numerous woody plants. In grapevine, these pathogens colonise the wood mainly through
pruning wounds, and the diseases gradually develop, leading to partial or total vine death. In the present study,
the three fungal species were grown in Czapek Dox modifi ed medium. Under these conditions, fungal colonies are
able to distinguish self from non-self. The production of reactive oxygen species (ROS) was analysed by specifi cally
staining for superoxide (O2
.-) or peroxide (O2
2-) radicals. The presence of ROS in both isolated cultures and fungal
interactions was confi rmed. All fungi produced both radicals, in every interaction. However, the patterns of ROS
production depend on the fungus itself and on the fungal species with which it is interacting, being also dependent on
the presence of antioxidant compounds in the surrounding medium. It is as though a fungal species hierarchy could
be established for every interaction under each set of conditions (i.e. habitat). The results obtained suggest that fungi
display more complex behaviours than generally acknowledged. They are able to recognize potential contestants and
built up defence reactions, as well as weaken plant defences and structures to induce infection