The aim of the study was to determine the causes of dying down of sprout and needles of Colorado blue spruce (Picea pungens Engelm.) and its cultivar ‘Glauca’ in the park collection of the Botanic Garden of Jagiellonian University in Cracow. For several years, the disease symptoms described in the article have led to the loss of decorative values of these trees. The study was conducted in the years 2002 and 2003 by means of the control of plant healthfulness, phytopathological diagnostics, isolation of microorganisms from tissues exhibiting diseases symptoms, as well as the culture and identification of the isolated fungi. Both, the control of tree healthfulness, and specialized laboratory techniques proved that the symptoms diagnosed in plants had an infectious character, and that the fungi might be the main causing agents. The analysis of the fungal populations isolated from the affected tissues indicates the combined occurrence of fungi in tissues of the studied plants and the domination of the following species: Alternaria consortiale, Aureobasidium pullulans, Penicillium canescens, Phoma pomorum, Ulocladium consortiale, Zythiostroma pinastri.

27-37