looks like somekind of canker...possibly from a fungus

Post a picture of the bottom of the trunk. The root flare should be visible and dramatically larger than the trunk. You should be able to step on the root flare. If not, there is likelya girdling root, or a constantly moist flare, which will put the tree in a great deal of stress. The stress will make the tree vulnerable to disease and pest attack. That is always the first thing to look at whenever a tree is sick. You hear me, all fellow tree peeps? :) M