The species Sirococcus tsugae occurs in North America (natively) and Europe (Germany, UK) on coniferous trees of the genera Cedrus and Tsuga. Naturally, for short distances, the pathogen spreads with the help of conidial spores by rain splash, for further distances probably by strong wind gusts and by moving infested plants. There is no information indicating that the pathogen can be transmitted with seeds. Conidia are formed on dead needles, stems or growth cones infected in the previous

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... . Infection most often occurs in spring and early summer, as young plant shoots are most susceptible. It is particularly dangerous in nurseries and plantations. S. tsugae can also attack adult trees. Climatic conditions in Poland allow the pathogen to establish itself (warmer regions of the country that allow the cultivation of cedars and Christmas trees), and this is also indicated by its presence in Germany. Due to the small scale of Cedrus and Tsuga cultivation, the pathogen can cause losses in nurseries producing planting material or infect trees growing in parks and gardens.