Septoria musiva, a fungal pathogen that causes cankers and leaf spots, is found in hybrid poplar plantations (Populus spp.) in southern Québec. A high incidence of severe cankers is observed on susceptible poplars. To accelerate the evaluation for resistance to Septoria canker, sprouts were inoculated with S. musiva twice in the nursery. From the 725 clones tested, 100 showed a low degree of susceptibility. Among these, 45 belong to the Ageiros section, 13 to the Tacamahaca section and 42 are hybrids between the two sections. The four isolates used in this test demonstrate variations in aggressiveness. Key words: Septoria musiva, Septoria canker, screening for resistance, hybrid poplars.