Butternut (Juglans cinerea) is an attractive nut-producing tree with ashy-gray bark that is smooth when young and becomes ridged with age. It’s a medium-sized tree growing to 30 m in height, closely related to black walnut (Juglans nigra). Butternut trees yield high-quality wood for furniture-making. The oily and nutritious nuts are an important food source for birds and mammals, and can even be grown commercially for human consumption.
The butternut tree is endangered and is protected under Ontario’s Endangered Species Act. It’s under threat from butternut canker (Sirococcus clavigignenti-juglandacearum), a fungal disease that kills most butternut trees it attacks. The disease was first identified in Ontario in 1991 and thought to have arrived accidentally in infected plants imported from overseas. The canker enters the tree through cracks or wounds in bark. Spores of the canker spread easily across many miles in wet weather. Surveys in Ontario show that most butternut trees are infected, and perhaps one-third have been killed.
Through our Natural Areas Inventory program, our biologists occasionally encounter butternut trees. Our biologists will note tree sizes, condition and location. While most butternut trees are sickly and cankered, finding healthy trees and trees with healed cankers are particularly interesting because they suggest a tree may be disease-resistant.
We inform landowners when butternuts have been found on their property. We also provide information on the Butternut Recovery Program. This program is a joint effort of different organisations including the Forest Gene Conservation Association. The aim of this project is to locate potentially resistant trees, collect cuttings and eventually develop canker-resistant nuts to repopulate the species. Landowners can opt to participate in this important program. Our hope is that one day we’ll see healthy butternuts once again dotting our landscape.
Finding healthy butternut trees through our Natural Areas Inventory program reaffirms the importance of monitoring our natural environment. It also shows the important contributions landowners can make to species recovery and leaving a legacy for future generations. Our work would not be possible without the cooperation of landowners in the Credit River watershed.
Learn more about butternut from the Forest Gene conservation Association.
Learn about other Species at Risk in the Credit River watershed.