Mountain Ash Tree - Ask Extension
Hi, I have a Mountain Ash Tree that has bark start to split on the trunk starting this past mid/ late Summer. I also noticed a mushroom growing out of...
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Mountain Ash Tree #922831
Asked December 12, 2025, 12:18 PM EST
Hi, I have a Mountain Ash Tree that has bark start to split on the trunk starting this past mid/ late Summer. I also noticed a mushroom growing out of a bark split about 6 feet up. I was wondering if this tree may be diseased or possible causes and any remedies if possible. Pictures provided. The mushroom fell/ got knocked off, but picture shows base of where it was.
Thank You!
Washington County Oregon
Expert Response
Dear John,
Thank you for contacting us about your tree. The tree bark seems to have several areas with significant wounds which leave it open to decay or pathogens. The photo with the mushroom looks as though a limb may have been broken off or pruned too deeply into the branch collar.
I suggest you consult a certified arborist to assess the condition of the tree and consider professional pruning to enhance the health of the tree. (Consultations can often be arranged at no cost.) You can locate a qualified arborist near you at
https://www.treesaregood.org/findanarborist/arboristsearch
I hope this information is helpful. Please write again any time you have a gardening question.
Thank you for contacting us about your tree. The tree bark seems to have several areas with significant wounds which leave it open to decay or pathogens. The photo with the mushroom looks as though a limb may have been broken off or pruned too deeply into the branch collar.
I suggest you consult a certified arborist to assess the condition of the tree and consider professional pruning to enhance the health of the tree. (Consultations can often be arranged at no cost.) You can locate a qualified arborist near you at
https://www.treesaregood.org/findanarborist/arboristsearch
I hope this information is helpful. Please write again any time you have a gardening question.
