Scientists in Vermont have been actively introducing Dutch elm disease to thousands of trees this summer. The initiative led by researchers from the U.S. Forest Service and the Nature Conservancy aims to assess the potential resistance of a new generation of elms, bred from disease survivors, to the fungus transmitted by bark beetles. This fungus has been devastating elm populations in the U.S. and Canada for many years. The ultimate goal is to restore areas where majestic elms once flourished, gracing city streets and riverbanks.
“The loss of trees over the years has been catastrophic,” expressed Gus Goodwin, a senior conservation planner at The Nature Conservancy. The experiment in Vermont seeks to develop a strain of elms resistant to Dutch elm disease (DED). Similar efforts in Canada are also underway, as researchers strive to combat the disease’s emerging threats.
The Elm City of Fredericton, previously renowned as the “City of Stately Elms,” witnessed a significant decline in its elm population during the 1960s and 70s due to the disease. Approximately 10,000 trees were lost, leaving only about 1,000 mature elms standing today. Professor Anthony Taylor, specializing in forest management at the University of New Brunswick, noted the ongoing impact of DED on surviving elms, emphasizing the disease’s rapid and devastating effects.
Bark beetles carrying DED spores play a pivotal role in spreading the fungus by infesting susceptible elms, causing blockages in their water-conducting tissues and eventually leading to the tree’s demise within a few years. To control DED, infected elms must be promptly removed. Historically, the practice of “sanitization” involved the removal of healthy elms along with diseased ones, inadvertently affecting the population’s tolerance to the disease.
Elm trees have faced significant threats across North America, with DED posing a renewed danger to urban forests in various regions. Cities like Edmonton and Saskatoon have reported increasing cases of infected elms, prompting swift action from authorities and residents to contain the spread. As the disease persists, preserving mature elms becomes crucial for maintaining urban ecosystems and adapting to climate change impacts.
Efforts to enhance DED resistance involve extensive research and breeding programs spanning decades. The Elm Recovery Project in Guelph and similar initiatives focus on crossbreeding and cloning disease-resistant trees to bolster elm populations. These long-term projects require patience, as generations of trees are cultivated and tested for resilience against DED. If successful, the reintroduction of disease-resistant elms could transform the landscape, offering hope for coexistence with the persistent threat of Dutch elm disease.