Biological environments contain a certain number of microbial populations which, within a givenecological niche, display various relations ranging from symbiosis to parasitism. Researchers have beeninterested in these types of relations for around fifty years, especially in one very particular type ofrelationship: the antagonism exerted between individuals of the same microbial population.Today, the role played by biological agents, bringing into play inhibitive or destructive antibioticsubstances, reveals a certain potential for their use in controlling microorganisms associated with suchdegradation processes.The work undertaken by HydroQuébec and CIRAD involved two types of experiment: 1) in Petri dishes toassess and characterize the antagonistic capacity of Trichoderma against white rot and brown rot fungi; 2)on pieces taken from untreated poles in order to study confrontation between the basidiomycete and theantagonistic strain in wood.This study investigated the antagonism of three ascomycetes of the genus Trichoderma against two whiterot 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 ofHydroQuébec poles.The results obtained seemed to complete each other coherently. They revealed that the Trichodermagroup of fungi was not aggressive to wood and the results obtained after direct confrontation in Petri disheswere confirmed in wood.By directly exposing the different basidiomycetes and antagonists to each other in Petri dishes, two bytwo, we effectively revealed an antagonism effect for a large majority of the pairs. However, there wassubstantial variability in reactions from one pair to the next.