Changes in production methods of Ericaceae ornamental plants could have caused them to become more vulnerable to weak pathogens. The aim of this study was to investigate the casual agent of Ericaceous plant damage. Plants and peat substrate were collected from two nurseries near Poznań. After isolation on agar medium and fulfilling Koch postulates it was found that the casual agent of Ericaceae ornamenta lp lant damage was Pestalotiopsis sydowiana (Bresadole) B.C. Sutton, a new species noted in Poland.