Question about our Katsura Tree

(Question)

We have a Japanese Katsura tree that I planted in the fall of 2013. In early summer of 2014 a raccoon attempted to climb on it as a shortcut off of our fence and snapped the trunk off about 4 1/2 feet above the ground. The tree is a small sapling about 11 feet tall and a bit over 1 inch in diameter at the break.

Upon discovering the damage I put the tree back upright (the splintered pieces fit together quite well) and because there was still at least half of the circumference of unbroken bark connecting the top to the bottom part and I put a splint of small bamboo sticks and tied it upright. The tree flourished all summer and had strong branch growth on the top part above the break line.

I have two questions. First, if the tree continues to survive will it eventually heal to the point where I don’t have to continue to wonder about the structural integrity of the tree? What I don’t want is to nurse it along and then have a mild wind snap it in two five years from now. I would consider starting over this spring with a new tree, even though they are expensive to replace.

My second question relates to the splint. How long should I leave it and how tight should it be, given that I don’t want to choke off bark growth. Will the wound eventually heal on its own?

Thank you

(Answer)

For the readership to understand your tree: Katsura or Cercidiphyllum japonicum is a tall-growing deciduous tree, loved for its attractive heart-shaped leaves and spectacular fall golden-red colour. Although native to China and Japan, katsura is known to be planted in certain Toronto parks and private properties, as specimen trees.

The tree trunk must have been, fortunately, still young and supple enough to have not snapped off entirely. To answer your first question: Trees have no wound-healing process, as in the sense of replacing, or healing damaged tissue. Assuming that “heal” means to restore to a previous healthy state, it is impossible to heal injured xylem or phloem. What do trees do, then ?  Trees have evolved as plants that  have the genetic capability to “compartmentalize” injured and infected tissues.

With this in mind, it sounds as though your tree has thrived quite well — with credit to your good first aid of setting the tree upright, applying a well-designed splint, and additional support. If your tree has thus far successfully fended off disease, or pests, at the break site, and has managed to grow “around ” the damaged tissue, then its trunk may very well continue to develop structurally sound, and robust.

But to answer your question about assurance of future survival, you may wish to engage a professional arborist, who can make a visual assessment of the splint, and the trunk, and help you with an expert prognosis.  All the very best !

For assistance in locating an arborist in your region, here’s the link to Landscape Ontario:  http://www.landscapeontario.com

And, also, TMG links to more information on Katsura Tree:  http://www.torontomastergardeners.ca/index.php/askagardener/katsura-redfox/