Bark coming off tree - cause and treatment? #137816 - Ask Extension


Bark coming off tree - cause and treatment? #137816

Asked June 30, 2013, 9:40 PM EDT

We have an autumn blaze maple planted 2.5 years ago. It is 2 inches in caliper now. 

It looks healthy except for a spot where the bark is peeling off (pictured). The bark there was brittle and flaked off. 

Under the bark we found several insects (also pictured). We've seen these same insects throughout our landscaping. It looks as if they burrowed a hole into the tree.

We're unsure if the insects are the cause of this problem or if there is some other problem that the insects are taking advantage of. 

Is this anything to be concerned about, and if so what should we do? 

Oakland County Michigan

Expert Response

There are  many  insects that will take advantage of any opening in the tree.  To identify the origin of the insect holes, you would have to be sure the insects you captured are the ones that made the holes.
The bark coming off can be from many causes, too-- animal damage, insect damage, lightning strike, frost cracks, disease, improperly removed branch; or there are some trees (Paperbark Maple and Silver Maple are two) that naturally peel. Young trees as they grow will naturally lose some outer bark. From your photos (very good, by the way), it appears it could have been started by a frost crack, a branch being removed, or as you noted, insects.

Trees naturally enclose damaged areas, and one of your photos shows this- the raised, rolled edges of light colored wood is the tree trying to close the 'wound' there. You should not paint the opened areas with anything. Research shows a healthy tree will naturally grow over the area faster if it is left open. 
Here is some detail on how trees deal with loss of bark: Splitting Bark article, from
"When a split occurs on a tree, what should you do? In recent years quite a bit of research as been done on closure of tree wounds. These investigations have indicated that tree wound paints are of little value in helping a tree to callus over. For this reason, do not paint or try to seal a split with paint or tar. .... A tree growing with good vigor usually calluses over quickest. Encourage vigor in the tree with yearly spring fertilizer applications and be sure to provide adequate irrigation in hot, dry weather. Bark splits will often close over completely, leaving a slight ridge in the trunk where callus tissue has been produced." (end of article extract)
The above indicates that a tree will callous over a 1/2 inch to 1 inch wide open area. Your tree can do so  if it is otherwise healthy and has the proper amount of water and nutrients. Continue to monitor your trees. If they otherwise appear healthy, they are callusing over on their own.
 For disease, insects or lightning strikes an arborist needs to be consulted. If the tree is of high value to your landscape, you can consult a certified arborist who can check for disease and insect issues and recommend a treatment plan.  Find an arborist by going to   then click on the "Find a Tree Care Service" tab. If you would rather just wait and see if the tree survives, give the tree good care-- mulch 3 inches deep out to the drip line (don't let the mulch touch the trunk), deeply water the tree during times of drought (a lawn sprinkler is not enough, use a soaker hose).
You can submit insects to the MSU diagnostic lab for identification. Their website will list their fees, and instruct you how to submit samples.

I hope this information is helpful. Thank you for using our service.
Laura Sheffer Replied July 01, 2013, 4:46 PM EDT

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