Demands and Opportunities for Selecting Disease-Resistant Elms

Abstract

The American elm is the unifying element of the Monumental Core of our Nation’s Capital. The National Mall, the focal point of the Core, is composed of 600 elms framing the vista between the Washington Monument and the Capitol. The National Park Service (NPS) has a mandate to sustain the American elms of the Core. Although Dutch elm disease (DED) has been a threat to this resource since 1947, the NPS has successfully managed the disease and continues to plant elms. The most promising long-term approach for sustaining elms is to plant DED resistant American elms or other elms having similar forms. Several new selections are now being incorporated into the Core including two NPS selections believed to be resistant to DED, NPS 3–178 and NPS 3–487. In order to hasten the screening process and increase the number of selections available, the NPS has entered into a Cooperative Agreement with Michigan State University to develop cellular and molecular rapid screening techniques for detecting DED resistance. Approaches include measurement of the in vitro response of elm calli to the DED toxin, cerato-ulmin, and identification of nucleotide sequence variations between resistant and susceptible elms.