Inoculation of Oak (Quercus robur and Q. rubra) with Collybia fusipes

International audienceCollybia fusipes has been reported as the cause of a root rot disease of oak trees in Europe. The pathogenicity of this fungus has not yet been proven by inoculation. C. fusipes was able to survive for more than one year in hazel stem segments or on oak root segments buried in non sterile soil, provided that these wood segments were incubated with the fungus for as long as 10 months before burial. We conducted three inoculation trials with 2-year-old oak seedlings. Inoculation success was strongly linked to ability of C. fusipes to survive in the inoculum. The fungus was able to induce substantial lesions (5-20 cm 2) in two growing seasons on vigorous seedlings, but none of the inoculated seedlings died in the course of the experiments. Defoliating seedlings for two years in a row did not increase the susceptibility to C. fusipes