Elm tree nursery at UMN Twin Cities, St. Paul
Background
Dutch elm disease (DED) is one of the most critical invasive pathogens in Minnesota. Caused by the fungus Ophiostoma novo-ulmi, it has decimated the American elm in urban Minnesota, a tree known for its elegant form, full canopy, and winter hardiness. As cities also contend with the widespread loss of ash trees to emerald ash borer, there is a need for new trees to fill the gap.
Researchers have been studying surviving elm trees in the region with the goal of understanding their natural resistance to DED.
Research questions
- What elm trees are disease-resistant?
- How can we best propagate resistant elms?
- What are the best methods to reintroduce resistant elms to the Minnesota landscape?
Outcomes
Held and his team have identified, propagated, and tested survivor elms from the Minnesota landscape, with some initially showing resistance to Dutch elm disease. They identified 23 new survivor American elm trees and propagated them for future testing.
From the 23 trees, they made 300 grafts to be used for future inoculation studies. They also made over 200 grafts that were planted in parks and natural areas. This includes Nerstrand Woods, Elm Creek Park Reserve, and Izaak Walton League in the Mississippi River Valley.
In addition, they screened by inoculation studies 15 elm selections from prior years. These showed very good to partial resistance in most selections.
Outreach
- Planting event with the Green Crew of Izaak Walton League - Minnesota Valley Chapter, 2023
- Urban Forestry Outreach and Research Community Forestry Field Day, 2022
- Northern Green Expo, 2022
- Upper Midwest Invasive Species Conference, 2020
News and media
- Interview: MN group working to end Dutch elm disease (WJON, 2023)
- Elms were once a staple of Minnesota's tree canopy; this is how researchers hope to bring them back (Star Tribune, 2023)
- A new realm of elms (CFANS news, 2023)
- Survivor elms: MITPPC-funded researchers are strategically wrangling the charismatic trees’ innate ability to fend off Dutch elm disease (MITPPC, 2022)
- Minneapolis woman saves 200-year-old elm destined for chopping block (Star Tribune, 2020)
- Undergraduate researcher Katie Connolly describe doing soil analysis work for elm restoration at home during COVID-19 (video, 2022)
- Developing Dutch elm disease-resistant trees (Minnesota Daily, 2020)
- A Guide to Elm Trees (HGTV, 2020)
- Elm Selection Project (The Urban Forestry Outreach and Research Nursery and Lab)
- Meet the Researcher: Ben Held (MITPPC)
Report a mature, surviving elm
If you know of an elm tree that may have survived Dutch elm disease, please let us know.