Imperfect state of Eutypella parasitica in culture

Abstract

Isolates of Eutypella parasitica Dav. and Lor. obtained from mycelial fans, infected bark tissue, and ascospores from different maple cankers produced conidia in culture on most standard media when exposed to light but not in the dark. Hyaline, one-celled, crescent-shaped, spores 1.3–1.8 μm wide and 25–32 μm long were extruded in gelatinous yellow or butterscotch cirri from pycnidiumlike structures or more open labyrinthiform structures which developed within the mycelium. Spores were borne terminally on branched conidiophores. The shape of these spores varied among different isolates. Conidia did not germinate when placed on several media, including host tissue, or when incubated over a wide temperature or pH range. The perfect state was not induced in culture despite various treatments, including incubation of mixed cultures for 2 years.