Occurrence, Mating Strategy, and Pathogenicity of Members of Nectriaceae in Central Appalachia

Stauder, Cameron

ABSTRACT: Members of the Nectriaceae occupy many ecological niches including dominant canker pathogens, such as Neonectria ditissima and N. faginata. These two pathogens contribute to the decline of American beech (Fagus grandifolia) forests across the Appalachian Mountains due to beech bark disease (BBD). Interestingly, N. ditissima represents a well-known canker pathogen many hardwood species, while N. faginata has not been observed outside of BBD. Additionally, N. faginata occurs at higher incidences than N. ditissima in BBD stands. Nectriaceae in Central Appalachia were surveyed as to further characterize the diversity and possibly identify a non-beech host of N. faginata. This resulted in the recovery of ten nectriaceous species from twelve tree species. Neonectria faginata only occurred on BBD trees. Neonectria ditissima was recovered eight tree species including Acer spicatum, Ilex mucronata, and Sorbus americana. Fusarium babinda was often recovered from BBD trees, but its role in BBD remains unclear. Corinectria gaudineerii sp. nov. was recovered from Picea rubens and Neonectria magnoliae comb. nov. from cankered Liriodendron tulipifera and Magnolia fraseri. The pathogenicity of N. magnoliae was confirmed, but the pathogenicity of C. gaudineerii was less apparent. Heterothallism for N. ditissima, N. faginata, and a number of other Nectriaceae was confirmed using molecular data and in vitro assays. This was important different mating strategies might explain differences in the ecology of N. faginata and N. ditissima. Together, these results demonstrate the diversity of Nectriaceae in eastern North America and their mating strategies as to further our understanding of dominant diseases affecting Appalachian forests.