Quick—if you think of endangered species, what pops into your head? Blue whales? Pandas?
How about butternut trees?
A native of the Carolinian forests common throughout southern and eastern Ontario, butternut trees are related to black walnuts. Unlike black walnuts, though, butternuts—which are valued for their edible nuts and soft, carvable bark—are at risk of becoming extinct due to a fungal infection that threatens up to 90% of the approximately 13,000 trees in the province.
Called the butternut canker, the fungus spreads quickly throughout the tree, cutting off the flow of water and nutrients. As the infection progresses, the tree loses branches and eventually dies.
While hybrids of butternut and Japanese walnut is able to tolerate butternut canker, most native, un-hybridized butternut trees are quickly succumbing to its effects.
To help save native butternuts from extinction, several groups supported by the Ontario Ministry of Natural Resources (MNR) and Environment Canada, including the Forest Gene Conservation Association and the Rideau Valley Conservation Authority, have launched a number of initiatives to study and preserve trees that appear to tolerate the worst effects of the butternut canker. Educational institutions like the University of Guelph and Humber College are researching methods of conserving the butternut population, and conservation groups across the province are planting butternut seedlings to give recovery programs a better chance.
“Biodiversity is crucial for all life on earth, and the survival or extinction of a single species affects the entire ecosystem,” explains Alexandra Link, the director of the Humber Centre for Urban Ecology and the Humber Arboretum, where staff and students are studying ways to propagate caker-resistant trees. “Helping preserve native butternuts is crucial to maintaining the unique character of the Carolinian Forest, which is the most biodiverse ecosystem in Canada.”
The limestone-based landscape of southern Ontario are prime butternut territory, but there’s no abundant species in any one location. Landowners play a key role in butternut conservation, so it’s important to know if you’ve got one on your property.
Landowners are a key element to butternut conservation, so it’s important to know whether you’ve got one on your property—and what to do if you do.
Identify your tree. Butternuts are small- to medium-sized trees that resemble black walnuts. They have leaves that are yellowish green and fuzzy on the underside and pointed at the end. To help you distinguish butternuts from black walnuts, the MNR produces a handy identification guide.
Report your tree. The Natural Heritage Information Centre keeps track of native species throughout Ontario, including butternuts. As well, the Forest Gene Conservation Association can help assess your tree for butternut canker. Get in touch with the Ministry to find out how butternut is protected under the Endangered Species Act, and particularly if you need to remove a naturally occurring butternut from your property, even if it’s diseased or dying.
Keep your tree safe. If you have a native butternut tree on your property, you may be eligible for stewardship programs through the MNR.
If you have a butternut on your property, consider trimming back surrounding trees. Butternuts grow in full sun—and every little bit of effort helps keep them around a little bit longer.