Soil factors associated with infection by Collybia fusipes and decline of oaks

Collybia fusipes is the cause of a root rot of oaks in Europe. Infection by the pathogen is site dependent and inconsistently correlated with crown deterioration. This study aimed at clarifying the relationship between soil factors and the impact of C. fusipes on tree health. The database of the Departement de la Sante des Forets, the forest health survey service, collected over the French forest during the last 12 years allowed us to perform a large scale study dealing with soil textures in which C. fusipes was reported to induce problems on Quercus robur and/or Q. petraea . Furthermore, a specific survey from 30 plots in north eastern France was carried out to determine which of the soil factors, such as texture, degree of waterlogging, presence and nature of a layer limiting rooting, carbon/nitrogen ratio, cation exchange capacity, or pH could be related to an increased risk of decline of pedunculate oaks infected by C. fusipes . The main results were that C. fusipes is preferentially distributed on coarse textured soils and that its negative impact on tree crown deterioration also increased with the soil sand content.