How to fix a tree with a split trunk from wind damage

December 15th, 2009

Readers of this blog will know that my favorite tree is my forest pansy redbud, indeed the related posts you’ll find at the bottom of this missive will point to the other blog posts where I have mentioned it. I love this tree because it has spring interest, in the form of the standard pink redbud blossoms, but it also has a somewhat unique purple colored leaf that creates nice interest in the summer as well.

I wanted one of these probably for 2 years before finding and buying one, and then, back in early October, disaster struck! A wind storm heavily, heavily, damaged the tree. Splitting the trunk in two places.

In retrospect going out and looking at the damage, it was bound to happen, the tree had grown so well that some limbs obviously outweighed the strength of their junction with the trunk, it should have had some preventative pruning done, but I was busy being a new dad.

Some people, when a tree is damaged like that, would just cut it down. If they think it’ll never be perfectly shaped again, they don’t want it. I personally think a tree that survives damage will have more character and be more interesting, plus, I did say it was my favorite tree, so I decided to repair it.

When faced with this sort of damage you really have two options, you can try to mend the split, which is possible when it is a 50/50 split or close to and there is still substantial amounts in tact on both sides. Or, if one side is severely weaker, it may not be able to be saved and so you’ll have to trim it up and make it as clean as possible. I had to do both.

The picture above is of the upper trunk split, this one you’ll notice is really severe with no structural integrity left on the right side. Trees do all of their physiology in the thin green moist layer right beneath the bark (xylem, cambium, and phloem layers, sometimes just called cambium) so if there isn’t enough bark area left to sustain the split branch, it’ll die. If you’re a few hours or a day after the damage and the leaves are wilting, you’ll know there isn’t enough cambium left. You might be able to do some heavy pruning so that the remaining foliage is better matched to the remaining cambium, but chances are you just need to cut the limb off.

So, for the damage shown above, the leaves were already wilting and the structure was so obviously compromised, so I cut the limb off, as cleanly as I could.

The above picture is of the lower trunk split. This is the first branching point of the trunk, the first main scaffold branch split off. In this case though the prognosis was much better, the leaves had not wilted in the least (and I was easily 8-10 hours after the storm) there was still structure integrity to the branch (it was hanging parrallel to the ground, not drooping all the way) and the split was probably 40/60. So I decided to fix it.

The first thing I did was some severe pruning to reduce the weight load of the branch. This branch had grown significantly during the summer and really weighed too much, I probably took off 70% of it’s mass. Just so I could lift it back into place as much as anything else.

I temporarily tied the branch up with twine, temporarily for a few reasons, namely because if you tie a tree you choke it. People run into this all the time with birdhouses. They do not want to “hurt” the tree so they use rope, twine, or wire (the worst) to tie a bird house to a tree. Really, the better thing to do is just to nail it. A tree can survive a puncture wound no problem, but if the tree grows into a rope or wire it’ll impede the flow in the cambium layer and choke it.

After the tree was in place I got out my power drill and bored a hole through the tree at the site of the split. Then I went down into my basement and looked through my screw/nut/bolt/nail organizer. In a bin called “toilet parts” I found some large brass bolts, these were perfect. Brass doesn’t rust, and being an alloy of copper it may have some antifungal properties. I put a large bolt through the hole and secured it.

I then drilled another hole a few inches above the split and put a longer bolt through there. I made sure the hole was slightly smaller than the bolt so I really had to shove and pound it in (thus making sure there would be no gap) and then I used a wrench to tighten nuts on both.

My tree was now a cyborg, and the actions I took may seem severe, drilling two holes, but as I said, trees can survive puncture holes no problem. There was another flap of torn bark and I actually brought out my nail gun and put some brad nails into that, more wounds, but the tree doesn’t mind them.

Eventually the tree will grow over those metal rods, incorporating them into it’s structure, and being all the more stronger for it, with no adverse damage, because they go through the cambium layer, not around it.

So, weight removed, gash mechanically repaired, now I had to worry about insects and diseases. I had both a can of tree pruning sealer and a can of natural shellac wood sealer. I had just read an article saying shellac was better than the other stuff and so used it. Shellac is an all natural waxy resin made by insects and used in everything from wood products, to food, to pills. You probably eat a little bit every day, it is harmless, but it seals wood good. Insects and diseases love open wounds and so it was important to seal the tree with something.

That taken care of, the last thing I needed to worry about was water. Just like with concrete, water can get in a crack, freeze, and then widen and make the crack worse. Even with the shellac the force of water expanding as it freezes was a potential hazard. What I eventually did, though which is not shown in the picture, is just put a bead of silicone caulk around the top of the crack (but not the bottom) preventing any water from seeping in, but if any does, still allowing it to seep out. Silicone is a neutral and inert substance and the tree will probably grow around it fine, or, after healing has progressed, I can take it out. Another option would be to wrap the tree in some sort of plastic, but that can hold in moisture too close to the bark and promote rot, I think my caulk solution is best.

I’ll post an update next year to show how the tree is doing.

Should you repair every tree? No, you shouldn’t, if there is a safety issue where the tree overhangs a structure or is where people often sit, walk, or play, you should always err on the side of safety. If the tree limbs are too big for you to manage to put back into place, you may not have to cut the tree down, but you’ll need to remove the limb. But, if your tree is not yet too large to manage (mine was only about 10 feet tall) you can try to repair it. It doesn’t need to be a total loss.

61 Responses to “How to fix a tree with a split trunk from wind damage”

  1. Sue B  Says:

    My beautiful Japanese fern tree split in storm today. Because the growth is perfectly ,naturally rounded should I cut this 20 ft tall down and start over or is there some way to save it?

  2. Mike V  Says:

    Snow load caused a 12 foot tall fruit tree to split 60/40 at the upper trunk. I cut off the large branch (40% side) above the split. What is best for the tree? Should I completely trim off the 40% flap exposing the heart of the tree or reattach the flap with screws or some other means to protect the interior?

  3. Administrator  Says:

    They make a spray, sort of like a liquid bandaid, to help protect open tree wounds like that. Find it here.

  4. David  Says:

    Great information. This is the first site I clicked on when I googled for this problem.

    How is your tree holding up now? Forest Pansy is one of my favorites too. I have four that I planted somewhere between 2005-2008.

    I just noticed a split at the Y of one of mine. I had been planning to limb it up somewhat, so doing so is on my list for today.

    The main trunk is about 7″, and the two sides of the Y are about 5″. I would need a 3′ long rod to span at a point where the rod would be fairly horizontal and not enter the limbs at a severe angle. This would be to get the holes to align.

    Any suggestions would be appreciated.
    Headed out now to trim.

  5. Administrator  Says:

    It never recovered and I replaced it some years ago. My efforts kept it going the rest of that year, but the following Spring the damaged limb did not leaf out.

  6. David  Says:

    This would be difficult to get the holes to align.

  7. bob kriesler  Says:

    I have a Chestnut tree thats huge and beautiful. 1 large branch broke off due to weight and water leakage at the trunk, approx. 16 inches thick. The break goes into the trunk maybe 3 inches and 2 feet long. Can I svae this tree?

  8. Nicola Suzanne  Says:

    Thank you for posting such detailed information. Hope your tree grows well for you.

  9. thomas byrer  Says:

    I have a peach tree that a large limb broke off of leaving very little of the main trunk about 10 feet up the tree can this be cut off and the tree live if I colt the top of the cut with roofing tar to keep out winter and bugs

  10. Debra H  Says:

    We have a 7 yr old redbud that has an 8 – 10″ split in the trunk separating the two main branches. I just saw the damage. It’s been there for at least 6 months or more. Will it cause disease if I try to tie it together now? Would look very one sided if I cut of the right half. Leaves on the right side are healthy and fine.
    Thank you!

  11. Rick  Says:

    We found 2 of the 3 limbs laying on the ground one morning after thunderstorms moved through. I lifted the fallen limbs and secured them to the remaining limb using rope. I then drilled 1/2 ” holes through the limbs. I used appropriate lengths threaded rods, 1″ washers and nuts. It’s only been weeks since the storm and the tree looks great.

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