I have a serviceberry in my west facing garden that is struggling. I am surrounded by a canopy of oak along the Humber river. The trunk has a blackened look, almost as if it has been burnt. I am wondering if you might know what would cause this? I also noticed that something has probably nibbled at the base of the trunk as some of the bark is missing. Any suggestions on what I could do to help this tree or should I take this opportunity to plant something new?
Thank you for contacting Toronto Master Gardeners.
Serviceberry grows best in full sun or mostly sunny sites, and prefers moist, well-drained soil.
Given its location near large oak trees, your service berry may not be getting enough light, and/or water to grow successfully.
The soil in which the tree is planted could be adding more stress to the tree. While the serviceberry can adapt to living in alkaline or neutral soils, it much prefers to be planted in acidic soils. These trees do not thrive in clay soils.
Your photo is not sufficiently detailed to determine the cause of the black look on the bark. There are many things that could cause your tree to be ailing.
It could be symptom of a disease, possibly blight affecting the tree. Here is some information on blight on service berries: https://www.yourleaf.org/sites/default/files/common_diseases_and_treatments.pdf
The nibbling damage on the trunk could be due to small animal foraging in winter. If the nibbling damage at the base of the trunk girdles the tree, it is unlikely to survive.
It is not possible from your picture to see if the tree was planted too deep. If a tree is planted too deep after a few years it will begin dying and the bark begins to break down. If the trunk does not begin to flair before it reaches the ground that maybe the issue.
If you contact an arborist they will be able to give a definitive diagnosis. You can find certified arborists at: https://landscapeontario.com/
You may need to replace the serviceberry with another native tree or shrub that will thrive in this location. Northern spice bush (Lindera benzoin) or nannyberry (Vibernum lentago) would be possible candidates. The following links have some great suggestions.
https://landscapeontario.com/landscaping-with-native-plants
https://www.ontarioinvasiveplants.ca/wp-content/uploads/2020/04/Southern-Grow-Me-Instead-1.pdf