The big snow split our old weeping Japanese maple (3-feet by 4-feet wide). The trunk cracked apart vertically about 2 inches wide and way down the middle. Should we tie it loosely around the stem so that it will not split any more? Should we allow the wound to heal by itself without any spray or dressing? Structurally, it does not seem that the split will make any difference.
The inner trunk wound cannot compartmentalize (heal), but the cambium layer just below the bark will "heal." Wrapping the wound to stabilize it and prevent further splitting is worth a try. It will not grow back together if too much time has elapsed since the split. Some people have luck with healing by wrapping duct tape around the trunk to pull the split sides together the sooner the better. See what happens next spring and summer. The weight of new leaves plus wind may split it further. Pruning off some lower branches should help lighten the strain on the break.