Microorganisms interact with trees in many ways, with relationships ranging from mutualistic to pathogenic. This project aims to characterize the fungal and oomycete communities associated with a variety of of economically and ecologically valuable trees, using DNA/RNA sequencing-based methods. Subprojects include analysis of ITS2 amplicons from fungal communities associated with Populus trees, identification of potentially novel oomycete species in publicly available metagenomics datasets, and PCR-and-culture-free detection and characterization of plant-pathogenic oomycete genus Phytophthora. The project will contribute to the resilience and preparedness of forestry and agricultural systems to existing and emerging threats from invasive microorganisms and climate change.