A beloved icon felled by a tragic illness. After years of obscurity, a triumphant return. Elvis? Greta Garbo? Michael Jackson? No—it’s the American elm (Ulmus americana), a native tree with a life story that rivals any Hollywood saga. An estimated 100 million elms have been wiped out by Dutch elm disease, which invaded the United States in the 1930s. Seventy years later, even as the disease continues to destroy mature elms, a comeback is taking place.
Several disease-resistant elm cultivars exist, and the one that’s grabbing headlines is the Princeton elm. This tough and beautiful shade tree, which grows 3 to 6 feet per year, was propagated from cuttings of a disease-resistant elm in Princeton, New Jersey. It’s tolerant of common urban problems like drought, heat, compacted soil, and pollution, and it grows in most soil types. Leaves turn bright yellow in autumn.
Common name: Princeton elm, Princeton American elm
Botanical name: Ulmus americana ‘Princeton’
Plant type: Deciduous tree
Zones: 3 to 9
Height: 80 to 100 feet
· Sun: Full sun or light shade
· Soil: Average, well-drained. Tolerates most types of soil.
· Moisture: Medium. Tolerates moderately wet and dry sites, but won’t thrive in tropical, desert, or high-altitude conditions.
· Mulch: Three to six inches of organic mulch will help the soil retain moisture. Don’t add mulch against the tree trunk, as this encourages rot.
· Pruning: Remove dead and dying branches about once a year while the tree is young and less often as it matures. Don’t prune during the growing season.
· Fertilizer: Check with your local extension service or a tree care professional. The wrong kind of fertilizer (or too much nitrogen) can damage an elm.
· By cutting. Seedlings may not carry the Princeton elm’s genetic resistance to Dutch elm disease.
Pests and diseases
· Dutch elm disease may infect a Princeton elm, but shouldn’t fell it. According to Riveredge Farms, propagators of the new elm, 95 percent of Princeton elms survive this disease and other landscape problems.
· Elm trees are big: up to 80 to 100 feet tall and wide. Be sure to plant the tree in a spot where it will have plenty of room. If you plant more than one, plant them 20 to 50 feet apart.
· The dappled shade under an elm is perfect for shade-tolerant perennials, bulbs, shrubs, and even small trees.
· Availability of the Princeton elm is still limited. If you live on the East Coast, look for a tree at Home Depot. You can also order trees from Riveredge Farms in Atlanta, GA (888-680-1922 or www.americanelm.com). Find more retail sites for disease-resistant elms at www.elmpost.org.
· Other Ulmus americana cultivars are available, including ‘Valley Forge’ and ‘New Harmony’.
All in the family
· Another member of Ulmaceae (the elm family) is Zelkova serrata, a tree from Asia. Zelkova serrata shares many similarities with the elm, and some have found it a satisfactory substitute.
(Text by Elizabeth Noll, photo of Ulmus americana courtesy of Missouri Botanical Garden’s Kemper Center for Home Gardening)