Role of Dasyscypha willkommii and Related Fungi in the Production of Canker and Die-back of Larches

The European latch-canker parasite and fungi closely related to and associated with it have been investigated in Europe for more than half a century. Nevertheless, at the time of its discovery in Massachusetts in 1927, the identity of the pathogen was understood imperfectly, and because of this its morphology as well as pathology needed further study. For purposes of control, it became necessary to distinguish the introduced parasite from related fungi including native species. Moreover the determination of its true host range, which up to this time had been greatly confused, became extremely important. Investigations by the writers not only settled the question of identity, but also demonstrated that the parasite attacks only species of larch and not the economically important Douglas fir and ponderosa pine. This paper presents experimental data which demonstrate that the larch-canker organism, and not related fungi, is capable of infecting both native and introduced larches, and of producing cankers and die-back in the absence of frost injury.