How long ago the damage occurred will have a big influence on how well the tree will "mend". Generally, the sooner after the actual damage happens, the greater the chances for successful repair. Trees begin their own healing process almost immediately and within 24-48 hours the wound will begin to scar over and the repair less likely to take.

If it is not a big tear, grafting tape can help. Match up the two sides exactly and wrap tightly. Grafting tape breathes so is preferred but I've seen success with duct and electrical tape as well. And it is a good idea to relieve the pressure on the split, so keeping the props in place should help also. Otherwise it may make better sense to just cleanly remove the broken/split branch. This joint will always be a point of weakness, even if it does heal.

Please advise re trunk wound on October Glory. She is 5 yrs (?) Injured 2 years ago by mower, has scarred but not over. Has open area which is dry,dark and not closing up. How should I treat this please. I love this tree.I am zone 4-5. She does not seem to have ill effects-just unsightly and I fear invasion to trunk center by critters, disease may occur. Will try to post pic. I have been using black wound spray and keeping it clean,dry.

Answered daisy.
Your tree has calloused over nicely.

Dax