Ailing Coral Bark Maple

Asked May 20, 2019, 6:41 PM EDT

  • The tree was planted professionally. The following year we accidentally broke off a couple of major branches, leaving the tree looking lopsided. I am not sure when we noticed the dark streaks on the trunk. The 3rd year we talked with an arborist about trimming the tree to make it more balanced. He diagnosed it with
  • verticillium wilt, an air borne disease and nothing we could do about it but it would not hurt the tree. He trimmed it lightly in March and said it would fill in with new growth. Three days ago (May 17) a small branch (about the size of my little finger) fell off and we thought nothing of it. A day later a large branch (size of my fore arm) fell off during the night. I am enclosing pictures of the tree and the open wound left by the broken branch. Is there any hope for the tree? What is the treatment for the tree? the soil? Should we take it out and replant it?

Multnomah County Oregon

3 Responses

Although Verticillum wilt is very common in the PNW on maples (like 80% of the time), I do not think this is that disease. My main worry is a large crack in the trunk. I see a crack in the trunk going from a discolored wounded area near the branches, that I assume the large limb fell from, all the way down past a weeping, darkly colored spot to near the ground. Weeping wounds of this nature tend to be due to winter injury followed by colonization my various microorganisms or Phytophthora canker. The limbs may have had tight angles to the trunk which can be weak points letting in the microorganisms. In time they may fall off as you have experienced.
If irrigation water is hitting the trunk then if could be Phytophthora canker. I see microsprinklers in one image so maybe it is not. You can read about that disease here and see an image:
As for winter injury, look at the 4th image down at this site:
In either case I think you will continue to experience branch problems until the tree heals itself. Branches on the side of the crack will be especially problematic. That may take a few years. Or it may continue to decline and die. Make sure irrigation water does not hit the trunk and give it good care. Not sure there is much else you can do for it.

Thank you for your explanation i=of our tree problem. Is there some way I should treat the wound where the branch broke off? or do I just need patience?

I do not know of any action you might be able to take at this time. There are no materials to apply to get rid of the problem. Keep the injured areas as dry as you can. We are heading into our summer dry period so that should be enough. It's kind of up to the tree at this point. You might think about another tree for that spot if this does not do as well as you want. Good luck.