You may have noticed that your tree appears to be bleeding sap from a wound on its trunk. If it has been there for a bit, it can also harden and appear golden yellow or brown. This symptom is known as gummosis. Do you need to worry if your tree is showing signs of this problem?

Gummosis itself is not a disease; as I mentioned above, it is more of a symptom that something is affecting the tree. For example, a birch tree may begin to bleed sap and develop gummosis if they are pruned early in spring, since sap is running high.

Other causes include diseases, insects and physical injury to the tree.

If you do notice gummosis, it's time to investigate. Try to figure out what is causing it to form. For example, borers leave holes in the trunk, so you may see evidence of that. You may have pruned too early or accidentally hit the wrong spot with pruners. 

Gummosis itself cannot be cured. Minimalize it by treating for diseases or insects and keeping the tree healthy In time, the tree may go through a process called Compartmentalization Of Decay In Trees where it walls off the damaged area. This will stop the bleeding.