May 5, 2011
My witch hazel was run over by a car about a year ago. The trunk seems to be healing and the branch that was broken is healthy, but a crack remains (1/8 inches wide and most of the way through). I have a C-clamp holding it together but I’m afraid it will fall away without it. The tree has only three branches, and it’s approximately seven feet tall. Can I put anything into/over the crack?
May 6, 2011
While it may not be what you want to hear, I would suggest pruning the broken or cracked branch off when it is suitable to do so in your area. Generally with witch hazels, this is done either during winter dormancy or following spring blooming. Don't worry though, new growth will emerge and the tree will survive. However, leaving it as is (or with a clamp) could leave the tree vulnerable to possible pest or disease issues.
Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/trees/tgen/what-to-do-for-storm-damage-trees-repair.htm