Black Tree Trunk - Ask Extension
Hello, I have a northern red oak in my yard and I noticed that this spring, it has a black tar substance on the trunk (see pictures). A cottonwood is ...
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Black Tree Trunk #870498
Asked May 28, 2024, 6:30 PM EDT
Hello, I have a northern red oak in my yard and I noticed that this spring, it has a black tar substance on the trunk (see pictures). A cottonwood is growing right next to it so I’m thinking it might be suffocating the roots? Main question is what I can do to save tree and/or is this tree going to die soon because of whatever this disease is?
Anoka County Minnesota
Expert Response
This is most likely a canker disease process. See the websites below for details.
1. https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/canker-diseases/
2. https://mdc.mo.gov/trees-plants/diseases-pests/hypoxylon-canker
3. https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/oak/branchescolor.html
We recommend an onsite assessment by a tree professional/arborist to identify the particular disease. They can identify the extent of disease and most appropriate action to take given that it is so close to the cottonwood tree.
https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional
1. https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/canker-diseases/
2. https://mdc.mo.gov/trees-plants/diseases-pests/hypoxylon-canker
3. https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/oak/branchescolor.html
We recommend an onsite assessment by a tree professional/arborist to identify the particular disease. They can identify the extent of disease and most appropriate action to take given that it is so close to the cottonwood tree.
https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional
