There are over 40 species of ash that are important to both the environment and the economy of countries located across five continents. Ash trees across the globe are currently facing two significant threats: an insect known as the emerald ash borer (EAB), and a fungal disease known as ash dieback disease. EAB is killing ash trees at an unprecedented rate in the United States, and five North American species of ash are considered critically endangered. Ash dieback disease, that has now reached 22 European nations, has not yet been found in the United States, but research has shown that at least some North American ash species are susceptible to the disease. EAB and ash dieback disease are both native to Asia, and Asian ash species have been identified that are resistant to both. As part of an international team, Northern Research Station scientists tested over 26 species of ash for resistance to EAB. Across the Atlantic, international collaborators are testing the same species for resistance to ash dieback disease. Genomic sequences of 1,400 genes from each of the ash species were generated and a novel approach was used to identify 53 candidate genes involved in resistance. These genes, once validated, have the potential to greatly expedite the breeding process and the production of resistant planting stock for restoration of EAB-decimated forests.