Distribution of Phytophthora Cinnamomi in Appalachian Forests.

Appalachian forests are under siege, threatened by invasive pests and pathogens, climate change, landuse change, and legacies of poor conservation and management. Phytophthora cinnamomi is an introduced oomycete pathogen causing root rot in American chestnut and shortleaf pine, among other species. While this pathogen has been present in the southeast US for nearly two centuries, its distribution patterns are poorly understood, making it difficult to prioritize locations for restoration of susceptible species. We collected soil samples from 47 continuous forest inventory plots in UK’s Robinson Forest, and successfully isolated P. cinnamomi from 18 of these plots. In addition, we screened 72 samples from reclaimed surface mined sites across a range of time since reclamation, and detected P. cinnamomi in 11 of 12 sampled sites. While P. cinnamomi is restricted to moist soils in low topographic position in some regions where it has been introduced (e.g., central Europe, eastern Australia), our preliminary survey detected this pathogen at both dry ridgetop sites and moist lowland sites. In addition, while reclaimed surface mined sites have been considered “phytophthora-free” because native topsoils with Phytophthora propagules are typically not retained during reclamation, our preliminary analyses suggest that P. cinnamomi is capable of rapidly colonizing even recently reclaimed sites. Additional spatial and soil physicochemical variables are under consideration as potential parameters influencing distribution of P. cinnamomi; these analyses are ongoing. These results suggest that P. cinnamomi is more ubiquitously distributed across the landscape than previously thought, and make a strong argument for continued development of disease resistant varieties of susceptible species.