Winter desiccation of dwarf pine (Pinus mugo Turra) needles in the area of Belmeken Dam

Abstract

In the summer of 2018, browning and drying of the needles on the dwarf pine (Pinus mugo Turra) formations in the vicinity of the dam Belmeken (Rila Mt.) were found. The damages were concentrated mainly in the southern part of the plants and affect the young needles on the tops of the shoots. During the route survey conducted in 2019, almost complete recovery of the affected plants was observed. Symptoms of drying were found only on single bushes. Studies and laboratory analyses gave reason to conclude, that the drying was due to adverse weather conditions in the winter of 2017-2018, when there was significantly less than normal rainfall, and sudden temperature changes and extremes were found. Established in the dry needles, fungi of the genera Lophodermium, Hendersonia and Neofusicoccum can be characterized as weak parasites, manifested secondarily, or as endophytes, which under physiological stress due to changes in certain environmental factors can become latent pathogens, worsening the condition of dwarf pine.