Pathogenicity of Sirococcus tsugae on major coniferous tree species of Belgian forest

Abstract :
To evaluate the potential impact of Sirococcus tsugae on Belgian coniferous forest, a pathogenicity test was conducted through wound inoculation of two-year- old seedlings of different tree species. Picea abies, Pseudotsuga menziesii, Pinus sylvestris, Larix x eurolepsis as well as Tsuga heterophylla and Cedrus atlantica were inoculated with an isolate of S. tsugae collected from the only known infected site in Belgium. The tested strain proved to be highly pathogenic towards seedlings not only of two known host species of the disease (T. heterophylla and C. atlantica) but also of L. x eurolepsis. This result highlights the risk that a possible emergence of S. tsugae might represent for some important forest tree species, including species currently not known as hosts of the disease. However, as the two main coniferous tree species in Belgium (P. abies and P. sylvestris) did not appear sensitive to S. tsugae, the potential impact of the pathogen on the Belgian forest is limited.