Pagoda dogwood (<italic>Cornus alternifolia</italic> L.) is a small understory tree native to the eastern half of North America. The plant is found both in the managed landscape and growing native in rich woodlands and swampy thickets. A major problem for the tree in both the managed and natural landscape is a devastating canker disease called golden canker or <italic>Cryptodiaporthe</italic> canker of pagoda dogwood, which is caused by the Ascomycete fungus, <italic>Cryptodiaporthe corni</italic> Wehm. The devastating effects of this fungus have caused concern among gardeners and arborists. This thesis reports results on a variety of different aspects of the host/pathogen interaction and include whether <italic>C. corni</italic> is capable of living as an endophyte in pagoda dogwood, more information about the etiology and epidemiology of golden canker, description of an effective artificial inoculation protocol resulting in disease, and the proper taxonomic placement of <italic>C. corni</italic> based on phylogenetic analysis.