Hi D@NI€”L’
This dream is both negative and positive. The positive side is that your son was or will be in a dangerous situation (a situation in which he could have suffered physical or psychological or even spiritual damage) but did not.
The tree is another person who poses a threat to your son. He will or has been successful in causing your son to trust him (your son climbing the tree).
The rotten speaks of this person not being a Christian and very bad. The fact that the tree was big in the dream speaks of this person being a strong or prominent person or that this person is “big” in the eyes of your son or that this person is a big threat or the threat being there for a long time already.
More good news is that the power or threat that this person has or poses to your son will suddenly go away symbolized by the fall of the tree. There is a slight possibility that this person may die because that is what it means when we see a tree falling down in dreams and visions.
The warning at the end will be well accepted when this happens because your son will be open to good advice when this happens.