Hello. Sorry I do not know much about trees so I'm not even sure what type of tree this is in my backyard. It is currently blooming and has green leaves and pink flowers. Some other trees have white flowers. Anyhow I noticed that one of the limbs appeared dead. It was missing bark. I grabbed it and it easily broke off. Then I noticed several others the same. I looked on the other side of the tree and noticed that the trunk appears hallowed out and there is a white residue on it. There is also a spider-like web in that area as well as on several bushes nearby. The rest of the tree seems fine but I am concerned about the tree dying and if this is a disease, spreading to nearby trees. Any ideas?