Does my ash tree have emerald ash borer? Should I get rid of it or treat? What to replace with?

Asked September 12, 2015, 3:29 PM EDT

Please see these 3 photos:


My questions:
  1. Does my tree have emerald ash borer (EAB)? I'm quite sure it does.
  2. Should I try to save it/treat it, or get rid of it?
  3. If I get rid of it, what should I replace it with?

If you'd just refer me to certified arborist, that's fine:
"Clients asking about how to save their tree should be encouraged to contact a certified arborist that is licensed to work in their city, or a nearby city if theirs doesn’t keep such a list. "


Details:
Many trees in my neighborhood are similarly sparse.
Furthermore, some trees in the local park are wrapped with warnings that they may be at risk for EAB;
I also tried:

My tree seems to have the symptoms, namely
  • Sparse leaves in upper part of tree. I think it's more than 50% canopy-thinned
I don't see any epicormic branches forming near the bottom, but I haven't yet inspected closely for the other symptoms.

I did check "what to do about it"

Today I will prune dead branches, at least.

I believe it is greater than 15" in breast-height diameter. So I'm prepared to hire a professional one way or the other.

It's the masterpiece to my landscape. I just built a retaining wall around/beneath the root flare. (I don't think I over-mulched!) But if it's a lost cause I'll get it removed and get a new tree started so it can grow into the retaining wall.

I'm trying to xeriscape everything, so any replacement ideally doesn't need much water.

What new tree would you recommend? I have a healthy oak in my backyard, and I'm thinking of one of these oaks:
  • White oak
  • Bur oak

Arapahoe County Colorado trees and shrubs ash trees

2 Responses

1. No, your ash tree is unlikely to have Emerald Ash Borer. To date, all 14 cases of EAB in Colorado have been confined to the City of Boulder. Many different causes or combinations of causes could cause an ash tree to have a sparse canopy of leaves.

One possible cause is Lilac-Ash borer, which is FAR more likely than EAB. Other factors include retaining wall construction. It seems probable that many of the existing roots would have been damaged or severed during construction; that alone could cause significant dieback of the crown/canopy. Further, if the grade was changed by adding soil over existing roots, they may not have access to oxygen as much as they did before the grade change, leading to root death and resulting crown dieback.
Finally, the last few years' weather has not been kind to ash. Late April freezes, just as leafing occurred, set back ash trees in 2013 and 2014. The Mothers Day freeze of 2015 similarly damaged new ash leaves. The Nov 11-12 'polar vortex' freeze killed water-conductive tissue just under the bark of ash and many other trees. These cumulative stresses caused some dieback in ash and many other trees (look at the weeping willow on your neighbor's property)

2. Your call on replacing it. As it looks now it is probably very stressed, making it very attractive to Lilac-Ash borer and other insect borers.

3. Kentucky Coffeetree, Skyline Honeylocust, Bur Oak or one of several others. Note that there is no perfect tree; all have some potential problems. Your photos suggest a hot, open, windswept location. See http://www.ext.colostate.edu/pubs/garden/treereclist.pdf

Awesome Robert, thanks very much. For everyone's information, here is a reply from Laura Pottorff, CDA

Nathaniel, Thank you for your email regarding EAB. Are there holes in the trunk of the tree? That is what we need to diagnose the presence of boring insects.

There are lots of boring insects that affect ash. The most common insects causing holes in the bark of ash trees are lilac ash borer and ash bark beetle. I have linked a couple of informational pieces for you to review. Size and shape of the hole in the tree will be one identifying feature you will need to look at.

http://www.ext.colostate.edu/pubs/insect/05614.html

http://nfs.unl.edu/documents/EAB/ashdeclineborersnotyetEABfullsheet.pdf

However, there is probably something else going on that is more likely given the location of your tree and what we have seen going on this year. To date, emerald ash borer (EAB) has only been detected within the City limits of Boulder. City Foresters and commercial arborists as well as the State have been looking at many ash all over the Front Range. We have looked a numerous ash trees in Englewood and south east metro and have not yet confirmed EAB in your area.

Many ash all over the Front Range are also exhibiting the symptoms your tree is expressing. We have seen that most of this is caused by damage suffered during November 10, 2014 when we experienced a 77 degree drop in temperature. On November 10 the high was 64 F and by the night of November 12, the record low was -13F. This was extremely damaging to ash and many other tree species in our area that had not 'hardened off' appropriately. Now that fall is almost upon us, the full extent of the damage suffered last November is becoming evident, as some new growth that was pushed out cannot be sustained.

Also, the statement that you made regarding 'building retaining wall around the tree' concerns me. When you put the wall in did you change the grade? Meaning was soil built up around the existing tree? It looks like the root flare is still visible which is good, but what about the area over the roots out toward the edge of the sidewalk and edge of the wall. And how long ago was this wall built? Were visible or shallow roots covered with several inches of soil out on this end? This could lead to changes in the way oxygen is made available to the roots in the area that was built up with soil.

When you take out the dead branches there will be less than 30% of the original tree canopy left. This is disconcerting and is often a 'line we draw in the sand' regarding decisions made to invest in the tree or cut losses. Ultimately the decision is yours to make. I would advise you consider removal and replacement. You can certainly wait until next spring to see if the tree releafs and make the decision then. But I don't think this tree is worth investing in pesticide treatments if a boring insect is present. I'll put is this way, if this tree was in Boulder (where EAB is present) it would not be a candidate for saving. If the tree is struggling with lilac ash borer or other boring insects, pesticide applications will not be that effective in this case either.

The oaks species you mention are great trees. This is a list of trees recommended for planting along the Front Range compiled by CSU Extension, the Colorado Tree Coalition, and Green Industry partners.

If you find boring insect holes in the trunk you may send pictures of the holes in the tree to me at the email above or you may certainly contact a certified arborist or Arapahoe County CSU Extension office at 303-730-1920. The other website you posted a question on will go to Araphoe County Extension, more than likely. I've copied Robert Cox, the Extension Agent there in this email. They can help with tree health care information and give guidance as well.