Repairing a tree that is missing bark usually requires only that you protect the exposed area and continue to care for the tree. Bark missing from the branches rarely kills a tree, but when bark is removed from the trunk, disease and insect pests can enter the tree. If the tree is completely girdled, the tree will likely die, although even a thin strip connecting one area of bark to another may be enough to save the tree.
Observe the tree closely to identify the cause of the missing bark. Possible causes include sun scald, animal damage or mechanical damage, such as from a lawnmower or string trimmer.
Cut any ragged bark edges back to smooth, healthy wood, rounding the edges. Continue to water and fertilise the tree, and it will likely recover on its own.
Take the necessary precautions to prevent damage in the future. For example, treat sun scald, which affects young, thin-skinned trees in the winter, by wrapping trees with tree wraps or painting them with diluted white latex paint. Wrap trees in tree wraps to protect them from rabbits, deer or voles. Remove grass from the base of the tree and mulch the area to prevent lawnmower damage.