The paper deals with the result of research on microorganisms colonizing leaves, stalks and leaf sheaths of the common reed (Phragmites australis). The studies were carried in 2010–2011. In each vegetation season the samples of morbid common reed were taken from the littoral zone around Płociowe Lake and Zdroje Lake in Drawa National Park (threefold from June till October). It was stated that the heterogeneity of phytopathogen and saprotrophic fungi and fungus-like organisms (FLO) amounted to 38 taxa. The symptoms of chlorosis and necrosis on the reed were non-specific (length from 1 to 300 mm and width from 1 to 35 mm) and connected with the occurrence of different etiological factors, individually and in complexes: Stagonospora, Fusarium, Helminthosporium, Deightoniella arundinacea, Scirrhia rimosa. Among the isolated species, the most frequent were: Alternaria alternata, Cephalosporium sp., Chaetomium globosum, Deightoniella arundinacea, Fusarium semitectum, Hymenopsis trochiloides and Phoma arundinacea. They were found on the reed from both lakes, in each year of research. The similarity species coefficient of micobiota for the reed of both lakes was 45.62%.

The paper deals with the result of research on microorganisms colonizing leaves, stalks and leaf sheaths of the common reed (Phragmites australis). The studies were carried in 2010–2011. In each vegetation season the samples of morbid common reed were taken from the littoral zone around Płociowe Lake and Zdroje Lake in Drawa National Park (threefold from June till October). It was stated that the heterogeneity of phytopathogen and saprotrophic fungi and fungus-like organisms (FLO) amounted to 38 taxa. The symptoms of chlorosis and necrosis on the reed were non-specific (length from 1 to 300 mm and width from 1 to 35 mm) and connected with the occurrence of different etiological factors, individually and in complexes: Stagonospora, Fusarium, Helminthosporium, Deightoniella arundinacea, Scirrhia rimosa. Among the isolated species, the most frequent were: Alternaria alternata, Cephalosporium sp., Chaetomium globosum, Deightoniella arundinacea, Fusarium semitectum, Hymenopsis trochiloides and Phoma arundinacea. They were found on the reed from both lakes, in each year of research. The similarity species coefficient of micobiota for the reed of both lakes was 45.62%.