The Search for Healthy Butternut Trees

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.

Butternut trees have compound leaves of 15 to 17 leaflets (each 9 to 17 cm long) and large, edible nuts that grow singly and are surrounded by a light green, sticky, fuzzy husk.
Butternut trees have compound leaves of 15 to 17 leaflets (each 9 to 17 cm long) and large, edible nuts that grow singly and are surrounded by a light green, sticky, fuzzy husk.

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.

Comments (17)

  1. Good morning

    There are some experimental butternut trees grafted on black walnut stock in experimental plot # 2 shared with ACER at Humber Arboretum. ACER has a mirrored experiment there with working with three nurseries in a gradient reaching south to Lake Ontario. (Sycamore and Yellow Birch )

    This plot#2 is on a slope facing south in the Toronto heat island as part of a long-term experiment with ACER
    ACER ‘s other experimental plot other experimental plot is on the floodplain below planted in 6 biodiversity experiments of 67 species (2002)
    The one hectare forest international plot has been inventoried since 2000.
    Interns finish their degrees with ACER updating data at Humber and at other campuses.
    Alice for ACER Find details at

  2. We planted both butternut and chestnut trees on our farm years ago. So far we have been lucky and they seem to be fine – at least at the moment. They are still quite young but look healthy..

  3. While participating in tree planting programs in my local area I have suggested it would be nice if we could plant butternut trees but typically they plant other species.

    I grew up on the ravine of erindale park in Mississauga and fondly remember seeing butternut trees and hearing the squirrels eat the nuts in the summer. I hope someone will contact me if I can be of any assistance as a volunteer or if there are sponsorship opportunities for a local butternut planting program.

  4. Hi
    I believe we have a butternut tree on our property. If you are interested in confirming the health of the tree feel free to contact me.

  5. We have numerous butternut on our property and they look healthy at this point. Someone from a study looked at them a few years back and decided they are a hybrid. I have lots of young ones that I pot up every fall and give to friends if you would like to have one or two to study

  6. A couple of butternut trees were planted on the school grounds at Belfountain Public School. I believe there is a healthy one but still very small. We would be happy to get involved in planting and research.

  7. We have 4 butternut trees in our backyard. One of them is losing its leaves presently (middle of August) and I wonder if it is normal. I would appreciate having someone to assess them. I love my butternut trees and would not want to lose any of them.

  8. We have a certified hybrid butternut tree and have planted nuts last fall. We now have 4 young trees that we think are butternut. Could you send us a picture of young butternut trees as we cannot find any pictures on the internet.

    Thank you.

    Ellen Smulders

  9. There is a large population of butternuts in my neighbourhood: Old Ottawa South. The trees range from seedlings to 40-year-old trees. So far I have not found canker on any, though I have my suspicions about a 6cm sapling near the Rideau River that has lost most of its bark and has a new shoot/branch growing from the base — typical of a diseased tree. The newer trees are most plentiful along the west/north bank of the Rideau.

  10. I have a mature Butternut tree in my backyard in Toronto. It killed off my apple tree and every year I have to tear out seedlings that grow very quickly and everywhere thanks to the multitude of squirrels in my neighbourhood. Butternut trees are toxic to fruit trees and a whole slew of other plants. If anyone wants seedlings, you’re welcome to them!

  11. We have a butternut tree in our backyard which appears to be healthy. Our neighbour butchered part of it that was hanging over their pool. Should I register this tree?

  12. There is a beautiful large old, possibly a champion, butternut in my neighbourhood that looks very healthy. Our community Is concerned about it and wants to try to save it. The property It stands on has just been sold and there are rumours the house could be torn down and a new home built that could cause damage to its roots. Please contact me and hopefully help us save it. Thank you

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