Dutch Elm Disease and Resistance

For nearly 10 decades, the invasive DED pathogen Ophiostoma novo-ulmi has been decimating American elms (Ulmus americana) and other native elm species in Minnesota and across the country. The American elm once lined streets across Minnesota, and for good reason. Its elegant form and tolerance to the harsh urban environment made it one of two premier canopy species. American, along with red (U. rubra) and rock (U. thomasii) elm, also provide critical benefits to ecosystem functioning, wildlife, and insects. Control measures so far have relied on sanitation and chemical control, both of which are expensive methods considering the large numbers of trees affected. Varied disease resistance has been identified in a small number of elms; however, additional genetic diversity is needed to combat a pathogen that has a changing virulence. Our elm selection program is aimed at identifying, propagating, and screening survivor elms for DED tolerance from across the state of Minnesota. In addition, our reintroduction planting program will also return much needed DED resistant genotypes back into the landscape in both urban and natural forested landscapes.