Scientists in Vermont have been conducting a unique experiment this summer, intentionally infecting thousands of trees with Dutch elm disease. The U.S. Forest Service and the Nature Conservancy are behind this initiative to test the resistance of a new generation of elms, bred from disease survivors, against the fungus carried by bark beetles. The aim is to eventually restore areas where majestic elms once thrived, gracing city streets and riverbanks.
Gus Goodwin, a senior conservation planner at The Nature Conservancy, expressed the devastation caused by the loss of elm trees over the years. The experiment in Vermont is part of a broader effort to develop disease-resistant elm trees, with similar research underway in Canada to combat the escalating threat posed by Dutch elm disease.
In Fredericton, once known as the “City of Stately Elms,” the disease wiped out around 10,000 trees in the 1960s and 70s, leaving only about 1,000 mature elms today. Professor Anthony Taylor, a forest management expert, has witnessed the disease’s impact on surviving elms on his property, highlighting the ongoing struggle against the relentless spread of the fungus.
The Dutch elm disease, transmitted by bark beetles, attacks the water-conducting tissues of infected elms, leading to their rapid decline within a few years. To prevent further spread, infected trees are promptly removed, a practice that aims to contain the disease but may have inadvertently weakened the elm population’s resilience over time.
As municipalities across Canada face new outbreaks of Dutch elm disease, cities such as Edmonton and Saskatoon are grappling with infected tree cases. Efforts to curb the spread emphasize prompt tree removal and community engagement to protect urban forests. The loss of mature elms not only impacts the aesthetic charm of elm-lined streets but also disrupts their ecological benefits, such as shading and stormwater management.
In response to the ongoing threat posed by Dutch elm disease, researchers in North America are actively working on breeding disease-resistant elms through crossbreeding and cloning programs. The Elm Recovery Project in Guelph and similar initiatives aim to enhance the resilience of elms against the disease, with long-term goals of restoring elm populations. The painstaking process of tree breeding and testing resilience will take time, potentially allowing elms to coexist with Dutch elm disease in a manner similar to European elms’ natural adaptation.
Despite the challenges posed by Dutch elm disease, researchers remain hopeful that efforts to develop disease-resistant elms will ultimately restore these iconic trees to their rightful place in North American landscapes.