All trees shed off their bark and crack to some degree. It’s simply their natural process of growing out of their skin. It could even just be the tree suffering from extreme elements, such as frost or extreme heat—in which some tender love and care to bring them back to a healthy state.
Some trees shed more than others, like the melaleuca tree that is so common to see in San Diego. This is a local tree that is ALWAYS shedding off its bark in a unique fashion that looks like paper peeling off, hence giving it its nickname—the paperbark tree. The various eucalyptus trees around the city are also notorious for molting. However, if a hardwood tree such as a pine has loose bark that comes off with a slight tug, then there is an underlying issue that should be inspected by a tree professional.
To better decipher whether your tree is going through its normal exfoliation process, look to see if there is a layer of fresh bark behind the shedding layer. If so, then that is a good sign that your is simply shedding. But if you see bare wood that has a fuzzy fungus or lighter-colered wiggly lines, then you have an issue. Your tree is suffering from either a fungal infection or a beetle infestation.
DISEASE. A common culprit for peeling bark on trees is a fungal disease called Hypoxylon canker. Its most popular victim is the oak tree, although different
Hypoxylon species will affect different host trees of choice. Being a fungus, it spreads through aerial spores, but will only cause harm to weak and stressed trees that are easy prey. Healthy trees typically have no issue defending themselves against Hypoxylon. In fact, many healthy trees already have the fungus on their outer bark, but they won’t be affected unless their natural defense mechanisms are compromised by factors such as malnutrition, drought, heat, insect attacks, etc.
Unfortunately, there is no known cure for Hypoxylon canker. Because the fungus lives in the interior of a tree, once the infection become evident from the outside, the irreversible damage has already been done. The typical protocol would be a removal of infected limbs or removal of the entire tree, especially if the fungus has affected the trunk.
BEETLE INFESTATIONS are a common cause for loose bark, especially with the pines in San Diego. The beetles feed mainly on the tree’s sapwood located just beneath the bark. This eventually causes the bark to loosen up and fall. Boring holes in the trunk are a tell-tale sign that the tree is infected with beetles, but for curiosity’s sake, if you wish to see their burrows, you can try peeling off a section of the bark—which will uncover a chaotic mess of the beetles’ burrowing lines. Take note though that if you are able to peel off the bark that easily, then the tree is beyond saving.