This tree is 6+ years old. It has been located in a full sun spot , regularly watered and pruned. During this spring I saw tremendous new growth but from past 2 weeks I noticed leaves weakening that look like not enough watered , eventually turning brown, new flower bud dying with leaves. The tree has 5 stems and only one tree stem with branches is affected right now. I cut off the branches with dead leaves. Here are pictures of branches with dead leaves, weakening of leaves started on another branch and a healthy looking leaves on another tree stems. Please help me identify the problem and help me save the tree. Thank you.