([WSL, Long-term treeline research at Stillberg, 2013-07-09, Internet](http://www.slf.ch/ueber/organisation/oekologie/gebirgsoekosysteme/projekte/stillberg_langzeitversuch/index_EN))
The 30-year period analyzed showed rather high mortality in both pine species [...]. P. cembra and P. mugo were mainly killed by the pathogenic snow fungi Phacidium infestans [...] The years when most trees are completely covered by snow in the early spring, and are therefore most susceptible to attacks by pathogenic fungi (in the case of pine species) [...]