Cankers are dead sections of bark, rather than a specific disease. You are welcome to share photos here, with details about your care for the tree and the problems you are seeing. As volunteers we can often point you the right direction.

If this is a high value tree in your landscape, consider hiring a certified arborist to make a site visit. Here is some arborist information. The page includes a tab for finding a certified arborist in our area. Inquire when you call to find one experienced in disease diagnosis.