Ash tree issues

I have a client that has 20 year old Ash trees on his property. This is the first year that the canopy’s of all three have had less than normal foliage. All the leaves on all three trees have brown dry tips, but not really losing what is there. I did not see any issue with Emerald Ash Bore. Hopefully you can see by the picks that there is a large amount of mulch piled up against the trucks. There is some mower damage but I would say not enough to cause this issue. Could they be planted to deep? They are a hybrid Ash but life expectancy I see is at least 100 years. I did tell the client to remove some of the mulch around the tree base. Any suggestions on why  the thin canopy and browning of the leaves would be appreciated.


  1. Hi Kara,

    The browning makes me think of certain foliar diseases, so it might be good to run these images by Brian Hudelson at the UW Plant Disease Diagnostic Clinic at some point.


  2. Kara: The tree does look as though it is planted too deeply, so that brings up the possibility of girdling roots that could be restricting water movement up the to the leaves. Definitely some of the mulch should be removed. With that much mulch around the trunk, there may be infections in the lower trunk that are inhibiting water movement as well. As you’re digging out around the base of the tree, I’d also check that (assuming the tree was balled and burlaped at purchase) all of the burlap, wire basket and supporting wires/cords/strings were removed. If not, that could be restricting water movement as well. Any of this could lead to a thinner canopy and the browning that you’re seeing.

    If this is an ash that seeds (it may not be), see if it seeded heavily last year. If it did, typically the year after the canopy will be thin as it’s used a lot of energy to produce all of that seed. Also, I can’t totally rule out that part of the problem could be minor cold injury from our harsh winter (think late January).

    Finally, I can’t quite tell from the photo, but is the browning more pronounced on the leaves on the lower branches? If so, anthracnose may be part of the issue (and there is likely at least some of this disease in the tree anyway. It’s been a good year). See for a fact sheet.

    Hope this helps a bit. Let me know if you have questions. Brian (:))

  3. Kara: Based on that distribution of the browning, I think anthracnose (as the primary problem) is less likely. I think there’s something inhibiting water movement up the tree. Verticillium is another disease that can restrict water movement in ash trees, but the pattern of brown leaves is not consistent with that disease. Typically I see a sectional dieback of entire trees with Verticillium wilt. Hope this helps. Brian (:))

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