The mycobiota of needles and shoots of silver fir (Abies alba Mill.) with symptoms of Herpotrichia needle browning in the Tatra Mts. (Poland)

The European silver fir (Abies alba Mill.) has the largest distribution area of all the European species of fir. It is the only species of this type found in the Carpathian Mts., including their highest range - the Tatras, where it constitutes one of the main components of lower montane forests. In certain sections of the Carpathian Mountains fir stands are affected by the competitive pressure of beech. This may be due to climate change, as well as biotic factors such as plant diseases. One such disease is Herpotrichia needle browning. The goal of the present research was to assess the occurrence of Herpotrichia needle browning in the Tatra National Park and determine the species composition of fungi colonizing symptomatic needles and shoots. Symptoms of the disease were observed across the entire research period, i.e., from May to mid-September 2019. They included the wilting of the needles with subsequent mycelial growth on the remains, as well as shoot deformation. The mycological analysis of the needles and shoots of A. alba resulted in the isolation of 22 fungal taxa. In the case of the needles and shoots, which showed symptoms of infection, the most frequent species of fungus was Sydowia polyspora (Bref. & Tavel) E. Müll., followed by Alternaria alternata (Fr.) Keissl. and Rhizosphaera macrospora Gourb. & M. Morelet. Herpotrichia needle browning seems to be triggered by a complex disease resulting from synergistic interaction of several fungal pathogens