Researchers in Vermont have been intentionally infecting thousands of trees with Dutch elm disease this summer. The aim is to test the resistance of a new generation of elms bred from disease survivors to the fungus spread by bark beetles, which has been devastating elm populations in the U.S. and Canada for many years. The goal is to eventually restore areas where elms once flourished, lining city streets and thriving along riverbanks.
Gus Goodwin, a senior conservation planner at The Nature Conservancy, described the loss of trees over the years as devastating. Similar efforts are also ongoing in Canada to combat the threat posed by Dutch elm disease.
The disease wiped out thousands of elms in the 1960s and 70s in Fredericton, once known as the “City of Stately Elms.” While some trees survived the initial wave of the disease, there is now a resurgence, leading to concerns for the remaining mature trees.
Dutch elm disease spreads through water-conducting tissue, causing the trees to wither and die within a few years of infection. To control the spread, infected elms are promptly removed. However, past practices of removing healthy elms alongside infected ones may have unintentionally reduced the disease tolerance of the population.
Cities like Edmonton and Saskatoon are facing increasing cases of Dutch elm disease, prompting swift action to remove infected trees and prevent further spread. Efforts are being made to manage the disease actively rather than attempting eradication, as the fungus is now widespread.
Despite the challenges posed by Dutch elm disease, researchers are working on breeding disease-resistant elms in projects like the Elm Recovery Project in Guelph. The long-term goal is to restore elm populations with trees that can coexist with the disease, similar to European elms.
This breeding program involves multiple generations of trees and will take time to yield results. If successful, it could lead to the coexistence of elms and Dutch elm disease with minimal negative impacts, offering hope for the future of elm populations in North America.