It’s important to pay attention to signs of tree health as early prevention is the best way to protect against the many factors that can pose a threat. Some damage is irreversible and can quickly turn a tree into a liability rather than an asset, especially if it affects the internal structure and makes the tree more susceptible to falling.
Both the roots and trunk of a tree and the surrounding layer of bark should be regularly checked for signs of disease or decay. Tree bark essentially functions as a protective layer and serves as the first line of defense against external stressors, such as insects, disease, or weather elements like sun and wind. If the bark is compromised, it can make the tree vulnerable to infection and decay that could then weaken the roots or main stem.
Make sure to regularly note any changes in the appearance of the bark, trunk, and the roots of your trees, especially if it doesn’t seem normal or seasonal. A certified arborist is always a great resource if you are stumped, and can offer important tree care tips. Having your trees seasonally or annually inspected by a professional is also a good thing to add to your property maintenance list because it’s easy to overlook subtle signs of damage.
A tree wound is basically just like a wound to human skin; an area on the protective layer is somehow opened up or damaged, making it vulnerable to infection and outside agents. Urban and suburban trees are more likely to have wounds than trees in a native forest because there is a higher risk of damage from factors such as automobiles, construction equipment, or lawn mowers bumping the tree trunk. Natural events, such as storms and lightning, fires, or damage by birds and other animals, can also create a wound in the tree.
Trunk wounds that penetrate the bark can damage the cambium layer, a thin layer of tissue within a tree that is very important to the movement of water and nutrients. This also makes the tree far more vulnerable to invasive organisms that can enter through the wound and cause decay.
Nearly all types of rot in trees are caused by fungal organisms, which can thrive in the wet conditions of the Pacific Northwest. Fungal infections pose a serious risk to the health and structure of a tree. You may have seen mushrooms growing on trees in shelf-like formations, which can appear almost decorative, but are in fact often indicators that a tree might be suffering from white rot or brown rot. There are also forms of fungus that appear as conks or knots in tree bark, so take note of any abnormal growths or areas of swelling.
Watch for subtler signs of decay as well, such as abnormal discoloration of the tree’s bark. Cracks and splits are not typical, and potential warning signs of underlying damage in the underlying tissues of the tree. Any wood that feels soft or crumbling is also a red flag, and if you happen to come across carpenter ants, that’s a good sign that there’s rotting wood within the tree.
If you notice wounds, fungus, or other signs of trouble, also take note of whether these are present in the lower section of the trunk, or around the visible parts of the tree’s root system. Any damage or decay around the base of your tree increases its risk of falling. Keep in mind that certain types of fungal spores can spread through soil, so if one tree base is affected, check the surrounding trees as well.
If you see any signs of rotting bark and decay, first assess how widespread the problem is. If only about 25% of the tree is affected, there may be the possibility of repairing the damage. If it’s closer to 50%, consulting with an arborist is the next step to take as rot and decay are difficult to reverse and tree removal may be necessary.
With manageable amounts of rotting bark, first mitigate the decay around the lower base of the tree by pruning the damaged roots. Then, use a trowel to dig out any soil or mulch from around the roots to eliminate excess moisture, and remove as much soil as possible from the entire base of the tree to allow the main roots to dry out.
Then, cut away any areas of damaged or rotting bark, making sure to not damage any surrounding healthy bark in the process. Avoid using tree paint on the remaining wound in the tree as this could introduce harmful chemicals to the underlying tree tissues. Make sure to thoroughly clean any pruning or gardening tools before using them again; this would include things like wheelbarrows or other items you use to haul away soil that may contain fungal organisms.
If it’s not too late to save the tree, applying a fungicide may also help. A typical application involves drenching the soil with a mixture of one gallon of water with two tablespoons of fungicide added. Repeat this procedure twice more at one-month intervals, but continue to keep an eye out for signs of decay because some types of fungus are resistant to treatment.
Prevention is also key. Don’t overwater your trees, or pile mulch or other high-moisture materials near the base, which could promote fungal growth. Protect trees from potential injuries and wounds caused by lawn mowers, cars, or other external factors. Cut out dead or diseased limbs. Make pruning cuts properly, promoting rainwater drainage. Scheduling regular tree inspections can also help detect issues that are harder to see from the ground.
An arborist will offer tree care tips to prevent rotting bark in the future. Remember that widespread rot and decay in your trees might mean removal is necessary, especially if the tree happens to be in an area where it could pose a risk to you or others (close to your home or garage, or near a neighboring property). Let a certified arborist evaluate the extent of the issue and help you reach a decision that will ensure your trees are cared for in the best and most responsible way.