In Vermont, scientists have been intentionally infecting thousands of trees with Dutch elm disease over the summer. This unconventional approach is part of a research initiative by the U.S. Forest Service and the Nature Conservancy to develop a new generation of elms that may possess resistance to the fungus carried by bark beetles, which has been devastating elm populations in the United States and Canada for many years. The ultimate aim is to restore areas that were once abundant with majestic elms, adorning city streets and flourishing along riverbanks.
Gus Goodwin, a senior conservation planner at The Nature Conservancy, expressed the profound impact of the elm loss over the years. The experiment in Vermont is a significant step towards potentially creating a strain of elms that can withstand Dutch elm disease (DED), offering hope for combatting the disease that is posing a growing threat in various regions.
Parallel efforts in Canada, such as the Elm Recovery Project led by the University of Guelph, are also striving to find solutions to the escalating spread of DED. Alison Morrison, a manager at the arboretum, emphasized the loss of the elms’ longevity rather than the entire population, highlighting the critical need to restore their ability to mature.
The Decline of Elms in the Elm City
Once known as the “City of Stately Elms,” Fredericton witnessed a drastic decline in its elm population during the 1960s and 70s due to the disease, resulting in the loss of around 10,000 trees. Today, only approximately 1,000 mature elms remain standing. Professor Anthony Taylor from the University of New Brunswick, who has surviving elms on his property, lamented the resurgence of the disease affecting his trees.
Dutch elm disease, transmitted by bark beetles, attacks the water-conducting tissue of elms, leading to a rapid decline in health and eventual death within a few years of infection. To control the spread, infected elms are promptly removed, a practice historically known as “sanitization.” However, this approach may have inadvertently impacted the trees’ ability to tolerate DED by eliminating potentially resistant specimens from the population.
The Battle Against Dutch Elm Disease
From Edmonton to Saskatoon, cities across Canada are grappling with the resurgence of Dutch elm disease in recent years. Edmonton has reported 17 infected trees since the disease reemerged in 2024, while Saskatoon has recorded 23 cases in 2026. These outbreaks pose significant threats to urban forests, prompting swift action by municipal authorities to contain the spread and engage residents in preventative measures.
Nolan Ramler, a park superintendent in Saskatoon, emphasized the community’s role in safeguarding elms and adhering to restrictions on tree pruning to minimize disease transmission. As the fungus becomes widespread, cities are transitioning to more proactive management strategies to mitigate the impact of DED on their urban landscapes.
Restoring Resilience in Elms
Efforts to enhance elm resiliency against Dutch elm disease through breeding and cloning resistant trees have been ongoing in North America. Projects like the Elm Recovery Project in Guelph have been dedicated to this mission for nearly three decades, focusing on preserving disease-tolerant genetic strains for future restoration.
The Vermont experiment represents a crucial phase in this endeavor, with researchers subjecting thousands of elm seedlings to DED spores to assess their resistance levels. While this breeding program entails a long-term commitment, the potential outcome could enable elms to coexist with the disease, similar to European elms that have evolved to withstand DED with minimal consequences.
Leila Wilson, a research ecologist at the U.S. Forest Service, emphasized the gradual nature of this process, spanning multiple tree generations over many years. Taylor highlighted the importance of expediting the co-evolution of elms with Dutch elm disease to ensure the survival and resilience of these iconic trees in the face of evolving environmental challenges.
