Zelkova Bark problems

Sidney, OH(Zone 6a)

This Zelkova was planted about 8 years ago and is about 20 feet tall. I know that Zelkovas often shed their bark, but this is the first year that the amount of shedding bark looks dangerously excessive. Is it because of the lack of rainfall we experienced over the summer? Although I've watered it, I haven't been as consistent as I probably should have been. It faces west, so it receives the hot sun in the afternoon. Should I be concerned, and if so, what can I do to save this beautiful tree?

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Scott County, KY(Zone 5b)

Your Zelkova has experienced a tremendous amount of damage to that side of the tree, and you have shown us a lot of dead bark that should be removed so that the callous/wound wood can close that damaged area.

When in the life of this tree did you create the planting bed around it? How did you prepare this ground? How do you maintain the planted area around the Zelkova? Do you use (or did others) use any pesticides during that process?

I would say this is a self-inflicted problem, but I'll await information from you.

Christiana, TN(Zone 7a)

Agree with VV about removing bark. The first willow oak I planted back in '88 got borers. By the time I realized it at least 3/4 of the bark was dead in one area. I removed all the dead bark I could find and sprayed an insecticide over the entire area. There was about an inch of bark left connecting the top and bottom and I was pretty sure it would die. Today it is huge and beautiful. It took about 2 or 3 years before the dead area was covered with new bark if I remember correctly.

Sidney, OH(Zone 6a)

Thank you for your responses. The bed around the tree was created right after the tree was planted, so it's been there for about 8 years as well. Last year and the year before, rabbits built a nest under the ground cover. The bark didn't look like this last year, and I'm not convinced that a shallow nest would create this type of damage. I've never used a herbicide in the circular bed either, although our lawn care company uses a granular herbicide when treating the lawn surrounding the tree. I'm going to remove the loose bark, spray with insecticide, and hope that the trunk will callous over the wounds successfully. Recommendations for insecticides? I use Neem Oil, Spinosad, and Bt, but I'm not opposed to using something stronger if it will help save the tree.

Scott County, KY(Zone 5b)

Remove the loose dead bark, stopping when you see green tissue which denotes where the tree is producing live callous wood to close over the wound. Use a sharp knife (like a pocket knife) to "prune" away remainder dead wood, so that new callous wood doesn't have to grow over it. This is much like cutting away soft or brown spots on fruit - bananas, apples, strawberries - before eating them. You don't cut away the good stuff, just the spoiled areas.

Show a series of images of your process of removing the dead bark, to demonstrate what you are finding (not just a "before" and "after" picture - show the "during" as well). Show through photos the areas where previously historical pruning cuts were made to remove lateral branches in this zone. I'm not convinced that you should use any remedial chemical or insecticide applications in this situation, since you have no determination of cause.

If there is no chance that this problem occurred due to pesticide/chemical use, and there has been no other physical trauma to the tree (struck by vehicles, mowers, string trimmers that could break the bark), then I think back to weather extremes and the kinds of problems associated with those events.

The Ohio River valley region - Sidney OH counts in that zone - has experienced some rather cold winters in the last 3-5 years. Recollect what your absolute lows were in the 2012-2013 winter and in the 2013-2014 winter. Consider the fluctuation of temperatures as well, warming prematurely in winter months and then sudden drops to subfreezing temperatures. I annually purchase plants from Ohio nurseries for the Louisville parks department planting projects, and we had difficulty receiving quality plants in a timely manner due to winter weather conditions/constraints during those recent years.


What direction does this trunk damage face? Aspect can be terribly important in regard to winter weather damage - especially warming periods followed suddenly by extreme cold events.

I will finally note your comments about animals around your plants. A nest doesn't cause the damage to woody plants; feeding by small furry fauna during winter months in pursuit of nutrients and moisture does! Ask any field grower of woody plants (or container plants, for that matter) about the problems of rodents and the trunks of trees and shrubs in winter months. Add severe winter weather conditions (and protective zones like living under mulch) and you have a prescription for nasty little nibblings that then shows up much later with a situation like you are describing.

This is another reason to never place mulch up against the base of trees and shrubs. You cannot observe any sort of problem like this, if it is hidden from view.

Christiana, TN(Zone 7a)

True about using insecticide. I should have said I didn't know any better back then. I don't know if it made any difference or not. Probably not.

Sidney, OH(Zone 6a)

I've removed quite a bit of bark that was loose and sprayed the trunk with imidacloprid. I didn't see any borer holes, but there were quite a few pill bugs and earwigs under the loose bark. I'm attaching photos to show the trunk from various directions. Photo #1 faces northeast; Photo #2 faces west; Photo #3 faces southwest; Photo #4 faces west; and Photo #5 faces east. Can anyone tell from the photos if I should remove more bark? Or should I cover the exposed areas with trunk wrap? We're still experiencing high temperatures (85-90) with bright sunlight. We still haven't had much rain, but I'm using a soaker hose to provide additional water. In an earlier message (Viburnum Valley), it was mentioned that the damage appeared to be self-inflicted. What does that mean?

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Scott County, KY(Zone 5b)

The early comment about "self-inflicted" was primarily in reference to the similarity of your damage to that exhibited when herbicides are improperly applied. You have scuttled that supposition because you don't use herbicides.

It may secondarily apply if the origin of this damage came from animals nesting in heavy mulch through a severe winter, and those animals chewed through bark on the base of this tree (under mulch) in order to gain moisture and survive.

Thank you for the images so far. Photo #3 seems to indicate the worst exposure with the most damage. That certainly could coincide with winter damage with large fluctuations between cold and warm. The sun will shine on this side of the tree in winter.

There is no need to do anything to this tree. The exposed wood is not live tissue, so no need to cover (and give bugs a hiding place). Watering through droughty periods via soaker hose is A#1 effort - good job. Remember that in future years, until your tree returns to its former vigor with a closed trunk wound.

I wouldn't try to remove anything else. Let the tree indicate to you what is still alive, or not, by flaking off like your original images showed. You will soon learn to identify this condition everywhere you go on many landscape trees. Thus, you can pass on your knowledge so that others may more healthily manage their trees.

Sidney, OH(Zone 6a)

Thanks again for the additional comments and suggestions. The soaker hose is continuing to provide extra water since our daytime temps are still quite a bit above average, and the drought is ongoing. I hope that this gorgeous tree can heal itself. And when I mentioned the rabbit nests, I was alluding to the nibbling of the rabbits, too, not the nest itself. I'm planning to rip out the ground cover this fall to make that area less inviting...that and letting my large dog investigate occasionally.

This message was edited Sep 24, 2016 2:44 PM

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