The mycobiota composition of plant phyllosphere depends on atmospheric factors as well as on the physiological properties of plant. In the recent years the infections of the eastern purple coneflower by Sclerotinia sclerotiorum, Botrytis cinerea, Fusarium oxysporum, Verticillium dahliae and by Erysiphe cichoracearum have been observed. The development of these pathogens is dependent on the species composition of the phyllosphere organisms, but it is also affected by the form and the level of nitrogen nutrition. The undertaken study aimed at the analysis of the mycobiota composition of the coneflower phyllosphere as dependent on the rate of ammonium sulphate used in the plant fertilization. The experiment was set up in 2007–2009 at Psary near Wrocław. Two fertilizer rates were applied: 50 kg N·ha^-1 and 200 kg N·ha^-1. The fungal taxa most abundantly isolated from the leaf surface of coneflower are: Cladosporium spp., Alternaria alternata, yeast-like colonies, Fusarium spp. and Epicoccum nigrum. These fungi make up > 90% of the isolated colonies., with C. herbarum and A. alternata as the dominant components of the assemblages. The dominant species within Fusarium spp. is F. equiseti. The species composition of the assemblages of fungi in the coneflower phyllosphere is variable and dependent on the course of the weather. The fertilization rate of ammonium sulphate does not affect the species composition of the phyllosphere fungi assemblages of the coneflower.

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