I planted a serviceberry (A. laevis) about 1.5 years ago, and it seemed to be doing really well until I noticed a few branches hadn't flowered yet. In the attached picture, you can see a black scar / blister / gall, etc. There are about 4 branches at the top of the tree with this scarring, including the main leader. Those branches have buds, but none of them have opened, and I'm guessing they won't - all the other buds on the rest of the tree have already flowered or leafed out. I don't see it anywhere lower on the tree. The tree is about 6 feet high, trained as a single trunk. Any idea what the problem is, and what I should be doing about it? Thanks very much,
The cankers you see look like they were caused by cedar quince rust. ( Some of the old decayed rust appears to still be on the right side branch.) This type of rust kills the wood beneath it. This infection occurred last summer.
Prune out the dead branches. You'll need to train a new branch to be the leader. Click here for rust info: https://extension.umd.edu/hgic/rust-diseases-trees-and-shrubs