Scientists in Vermont have been intentionally infecting thousands of trees with Dutch elm disease this summer. The purpose of this unusual experiment is to assess whether a new generation of elms, bred from trees that have survived the disease, might possess resistance to the fungus transmitted by bark beetles. This fungus has been wreaking havoc on elm populations in the U.S. and Canada for many years. The ultimate goal is to restore the once-abundant elm trees that used to grace city streets and riverbanks.
Gus Goodwin, a senior conservation planner at The Nature Conservancy, expressed the devastating impact of the loss of elm trees over the years. The hope is that the experiment in Vermont will yield a strain of trees that can resist Dutch elm disease. Similar efforts are underway in Canada to combat the threat posed by the disease spreading to new areas.
The decline of elms is evident in Fredericton, which was once dubbed the “City of Stately Elms.” The disease struck the city and other parts of eastern Canada in the 1960s and 70s, leading to the loss of an estimated 10,000 trees. Only around 1,000 mature elms remain today. Professor Anthony Taylor, a forest management expert at the University of New Brunswick, is witnessing another wave of the disease affecting surviving elms on his property.
Dutch elm disease, carried by bark beetles, attacks the vascular system of elms, blocking water movement and eventually killing the tree within a few years of infection. To combat the disease, infected elms are promptly removed. However, past practices of removing healthy elms alongside infected ones may have inadvertently decreased the population of disease-tolerant trees.
Cities across Canada are facing a resurgence of Dutch elm disease, with Edmonton and Saskatoon reporting increasing cases. Efforts to manage the disease include the removal of infected trees and community cooperation to prevent its spread. The loss of mature elms poses challenges for urban environments, affecting their ecological functions and resilience to climate change.
In an attempt to enhance resistance against Dutch elm disease, researchers in North America are breeding and cloning disease-resistant trees. Projects like the Elm Recovery Project in Guelph have been ongoing for nearly three decades, aiming to create a population of disease-resistant elms. The long-term experiment in Vermont involves infecting thousands of young elms to identify those that can resist the disease.
While the process of breeding disease-resistant elms is time-consuming, it offers hope for the coexistence of elms and Dutch elm disease in North America. Natural evolution of elms in response to the disease could take centuries, but active interventions aim to expedite this process. The restoration of elm populations is crucial for maintaining biodiversity and ecosystem resilience in the face of climate change challenges.