Histological Evidence that Microsclerotia Play a Significant Role in Disease Cycle of the Boxwood Blight Pathogen in Southeastern United States and Implications for Disease Mitigation

Cylindrocladium pseudonaviculatum, the causal agent of box blight, has been shown to survive in soil for at least 5 years. The occurrence of microsclerotia in host tissue remains undocumented, making the mechanism for long term survival of this pathogen unclear. If the boxwood blight pathogen has indeed lost or never evolved the ability to produce microslerotia in tissues, one could infer that the pathogen is either less equipped for long term survival in soil than other Cylindrocladium species or the pathogen has evolved another mechanism to enable it to persist in soil. Based on these assumptions, we conducted a histological study to determine the potential role, if any, of microsclerotia in the lifecycle of C. pseudonaviculatum. Accepted for publication 17 February 2012. Published 3 April 2012.