Cherry Tree is Sick
I have a cherry tree that was planted 3 years ago. It is a hybrid of three different species (one branch is native, the two other are not). The tree looked healthy and did grow relatively fast for a couple of season.
This spring I noticed that two of it's vertically-pointing branches have the leaves dying off. I noticed about a couple dozen of leaves on the healthy branches infested with insects, accompanied by ants. There were also a few ladybugs around.
Finally, this year I see active gummosis happening all over the tree. Did I prune the tree too much and too poorly?
Is it suffering from more than one disease? How do I help the tree recover?
Within 10 meters (~30 feet) there is a peach tree which is sick but seemingly in a different way. I am only mentioning it for the context.