Fungi associated with disease symptoms on Pinus mugo needles in the Polish Tatra Mountains

Dwarf mountain pine, Pinus mugo , is an important component of the subalpine and alpine zone in Europe. For several years, in one of the natural areas of the occurrence of this species in the Polish Tatras, an intensified decline of the assimilation apparatus has been observed. The studies conducted in 2016–2020 were aimed at determining the types of disease symptoms occurring on P. mugo needles and at identifying the species composition of fungi within symptomless and diseased needles. We isolated 57 taxa from 6 types of disease symptoms and from needles without disease symptoms, identified on the basis of morphological features and molecular analyses. Absolute parasites were represented by only one species of Coleosporium senecionis , which was identified by the aecium stage. The genus Lophodermium was represented by three species: L. conigenum , L. corconticum and L. pini-mugonis . So far, L. corconticum was known only from the Karkonosze Mountains in Poland, and L. pini-mugonis from the German Alps. In addition, the more frequently isolated species included: Sydowia polyspora , Hendersonia sp., Nemania serpens , Leptomelanconium allescheri , Cladosporium spp., Biscogniauxia nummularia and Alternaria spp. Some taxa were associated with only one type of disease symptom, while some species of fungi were found to be associated with different symptoms. Twelve species of fungi were isolated from living symptomless needles, some of which were subsequently found in association with nectrotic areas on needles, e.g., L ophodermium corconticum , L. conigenum and Leptomelanconium allescheri . L. pinastri has not been found in the present studies. In the discussion, an attempt was made to assess the role of some of the identified species of fungi in causing the disease process of P. mugo needles.