Decay can't be reversed once a tree begins to succumb, but it can take many years before decay damages become obvious enough to warrant concern. Knowing the signs of advanced decay and internal rot can help you spot problem trees that need to be removed.
1. Severe Bark Loss
As decay kills the tree from the inside out and the roots up, the bark is one of the first of the visible woody portions to break apart. It may crack and crumble, or even become spongy. Discoloration is common, as well. Bumping against the tree may also easily dislodge the bark, revealing the inner wood of the trunk. Continuing bark loss will weaken and speed up the death of the tree.
2. Boring Insect Damages
A variety of different insects pest will bore into the trunk of a tree. Decay weakens a tree, making it more prone to insect damage and more attractive to those insects that feast on dead wood. You may notice small holes all over the trunk. Sawdust may also be present on the trunk or on the ground surrounding the tree. Boring damage will further weaken wood, which can increase the chances of a broken branch or tree blowdown if the tree isn't removed.
3. Fungal Growths
Fungus is sometimes the cause of tree decay, but even when it isn't the main cause it still is typically present in a rotting tree. Most of the fungus will be deep within the wood where it can't be seen, but occasionally it may fruit. When this occurs, you will see mushrooms growing along the trunk of the tree or on the soil coming up from the roots. The heartwood is likely quite decayed at this point, making removal the best option.
4. Oozing Sap Wounds
As the tree begins to die, it may become prone to sap seeping wounds. These wounds can form along cracks where the bark is crumbling, for example. They can also result from pests and fungal pathogens that are beginning to prey on the weakening tree. Not only are these wounds a sign that the tree should be removed, they will also drip a sticky mess on anything below.
5. Cavity Formations
Severe decay typically affects trees from the inside out, so a tree that looks fairly healthy on the outside could be riddled with rot on the inside. As decay progresses, cracks and gaps may form on the trunk. Inside of these cracks will be cavities or hollows where wood has already rotted away.
Contact a tree removal service if you suspect that decay has caused irreparable damage to one of the trees in your yard.