The University of Minnesota, alongside researchers worldwide, has been conducting research into species of elm that are resistant to Dutch Elm Disease. Many of the species and varieties that display resistance are elms from other parts of the world, especially Asia.
The St. Paul Campus of the University of Minnesota has several examples of these resistant elms planted around campus. A few are listed and mapped below.
Discovery Elm is an older resistant cultivar bred by Canadian researchers. It is a very drought tolerant and cold hardy variety, but is very slow growing. Trials at the University of Minnesota reveal it to have a relatively upright form. The two elm trees between Coffey Hall and the Biosystems and Agricultural Engineering Building are Discovery elms and were planted in 2003.
Cathedral elm is a long-time favorite for DED resistant elms. It was used to replace all the elms that died on Northrop Mall on the Minneapolis campus of the University of Minnesota. It appears to have excellent resistance to DED and to urban pollution, but it does seem to attract leafhoppers. It has a more vase-shaped growing habit. Both elms on the north side of Fitch Ave are Cathedral elms, and were planted in 2014.
Pioneer elm is a hybrid between the Wych elm (U. glabra) and field elm (U. carpinifolia, also known as U. minor). It has a different, less upright form than the Asian or American elms, but is easy to train. Research indicates that Pioneer elms are only hardy to USDA Hardiness Zone 5, but despite being in Zone 4, trees planted in St. Paul have survived since 1999.