Question
We have a pink dogwood tree in our backyard. It's leaves show no sign of anthracnose or any other disease described on any internet article I have read, however, the bark on the trunk is peeling away. Our local nursery thought that it was because we improved the growing conditions by removing some large firs which were blocking the light, but it has now been more than a year and the bark continues to peel away. The tree has lots of foliage and blossoms, and as well, the leaves are well formed. I am concerned that another year of the bark peeling (from root to where the branches fork) could be the demise of the tree. Any suggestions would be appreciated.

Answer
Bark splitting can occur in response to various environmental factors at different times of the year. In your case it would seem like a sun burn--the tree that was in the shade is now in direct sunlight. And the heat form the sun caused the burn. The same thing can happen in the winter months.

Sunscald, especially in winter months, can cause bark injury to thin barked or young trees. Although an exact split may not be seen immediately, the outer layer of bark will peel away from the affected area in the summer following winter damage. Sunscald injuries to tree limbs can be minimized by avoiding heavy pruning of trees which have dense canopies. Gradual thinning of limbs over a period of years is preferable, particularly on thin-barked trees.

Fluctuating growth conditions may also cause splitting of bark. Dry weather (which slows growth) followed by wet growth conditions may cause an excessive or vigorous amount of growth leading to splits in the bark.

Sunscald, especially in winter months, can cause bark injury to thin barked or young trees. Although an exact split may not be seen immediately, the outer layer of bark will peel away from the affected area in the summer following winter damage. Sunscald injuries to tree limbs can be minimized by avoiding heavy pruning of trees which have dense canopies. Gradual thinning of limbs over a period of years is preferable, particularly on thin-barked trees.

When a split occurs on a tree, what should you do? In recent years, quite a bit of research has 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.

Cleaning the edges of the wound, known as "tracing," can be very helpful in aiding healing. Do not enlarge the wound any more than necessary to clean the edges! With a sharp knife, starting from one end of the split, trace around one side of the wound, no more than one-half to one inch back from the split bark. Stop at the other end and do the same procedure on the opposite side of the split. Knives should be sterilized between cuts by dipping for several minutes in a 1:10, bleach:water solution or a 70 percent alcohol solution to avoid contaminating the cuts. Carefully remove the bark from inside the traced area.

You should now have a bare area with smooth edges. Remember to leave this untreated. A tree growing with good vigor usually calluses over quickest. Encourage vigor in the tree with spring fertilizer applications--but only if the tree exhibits signs of nutrient deficiencies--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.  
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