Biological environments contain a certain number of microbial populations which, within a given ecological niche, display various relations ranging from symbiosis to parasitism. Researchers have been interested in these types of relations for around fifty years, especially in one very particular type of relationship: the antagonism exerted between individuals of the same microbial population. Today, the role played by biological agents, bringing into play inhibitive or destructive antibiotic substances, reveals a certain potential for their use in controlling microorganisms associated with such degradation processes. The work undertaken by HydroQuébec and CIRAD involved two types of experiment: 1) in Petri dishes to assess and characterize the antagonistic capacity of Trichoderma against white rot and brown rot fungi; 2) on test-pieces taken from untreated poles in order to study confrontation between the basidiomycete and the antagonistic strain in wood. This study investigated the antagonism of three ascomycetes of the genus Trichoderma (Trichoderma konigii, Trichoderma harzianum and Trichoderma viride) against two white rot basidiomycetes, Pycnoporus sanguineus and Coriolus versicolor, and two brown rot basidiomycetes, Antrodia sp. and Coniophora puteana, through direct confrontation in Petri dishes and in the wood of HydroQuébec poles. The results obtained seemed to complete each other coherently. They revealed that the Trichoderma group of fungi was not aggressive to wood and the results obtained after direct confrontation in Petri dishes were confirmed in wood. By directly exposing the different basidiomycetes and antagonists to each other in Petri dishes, two by two, we effectively revealed an antagonism effect for a large majority of the pairs. However, there was substantial variability in reactions from one pair to the next. For instance, the antagonism mechanism of the same Trichoderma could vary from one basidiomycete to another, and inversely, the same b