Hi Thomas,

Thanks for your question. It does look like cytospora and yes, you can cut off the branch, back to the main trunk, to remove the canker. But if the branch is healthy and has buds that are viable, you may consider leaving it.

Cytospora is caused by stress--often from drought, planting improperly, improper pruning, late spring frosts, etc. This looks like a very young tree, so perhaps it became stressed after planting or from the very hot summer we had last year. So your first steps are to eliminate the cause of the stress. Increase cultural health, water properly, mulch the base of the tree, make good pruning cuts, etc. 

If you do prune this branch, disinfect your pruners between cuts--either spray with Lysol or dip in a diluted bleach solution. Also, prune during a dry period without any rain/snow. Pruning can happen between now and budbreak.