Stegophora ulmea is an ascomycete fungus native to North America. It is one of the most important emls (Ulmus spp.) pathogen. Pathogen may cause serious economic damage in forest tree nurseries and areas with high elms density. There are three elms species in PRA area: wych elm (U. glabra), field elm (U. minor) and European white elm (U. laevis). All of those species are potential S.ulmea host plants and may be infected with ascospores. Considering that climate conditions in PRA area are favorable for fungus it is expected that it will be able to spread in Poland.

Elms import (including bonsai trees) is not popular, therefore this way of fungus entry is insignificant. Strict controls of imported plants (especially from area of S. ulmeaoccurence) reduce the risk of fungus establishment. Spraying pesticides and/or removal of infected plants from forest tree nurseries are necessary phytosanitary measures.The pathogen monitoring is almost impossible in case of Stegophora ulmea occurence in natural environment.