Features: The Butternut (Juglans cinerea) is a medium-sized tree that belongs to the Walnut family, and like the other native walnut in Ontario, the Black Walnut, it produces edible nuts in the fall. The roots of Butternut secrete juglone, an allelopathic chemical that can kill other plants growing nearby.

Status: Endangered Provincially and Nationally

Range: The Butternut occurs in eastern North America, ranging from Georgia, Alabama, Mississippi and Arkansas west to Iowa and Missouri, north to southern Ontario and Quebec, and east to New England. In Ontario it is found throughout southwestern Ontario north to the Bruce Peninsula and the edge of the precambrian shield. Range Maps

Threats: Butternut trees are normally found scattered at low density in forests, and were thus never common in Ontario. Historically, they have declined as forests have been cleared. Today, the main threat to Butternut is a serious fungal disease called Butternut Canker, which was first found in Ontario trees in 1991, but has been in North America for about 50 years. It is thought to have arrived accidentally in infected plants imported from overseas. The fungus can kill a tree within a few years of infection. It enters through cracks or wounds in the bark and multiplies rapidly, making sunken cankers that expand and girdle the branch or trunk, killing everything above the canker. Fungus spores can be transported in wet weather for miles, and the disease can spread quickly. In southeastern states such as Tennessee, the disease has already killed about 80% of the Butternuts. In Ontario, surveys in eastern Ontario show that most trees are infected, and perhaps one-third have been killed.

Protection: Protection provided to the Butternut under Ontario's Endangered Species Act, 2007, prohibits any type of harm to this species. Butternut does grow in some national and provincial parks in Ontario where trees receive protection from cutting. Most trees, however, are on private land. There is no known cure for the canker disease, nor any effective techniques to slow or prevent the spread of the disease. The Ontario Forest Gene Conservation Association has established a Butternut Conservation Group, and one of its main objectives is to locate disease-resistant individuals and use these to propoagate tree seedlings for planting.

Text Sources: Neilson et. al. 2002

Last Modified Date: Ontario 2008