Split trunk to eliminate reverse taper

[Cajunrider]

I have a tree with a slight reverse taper. I am thinking about splitting the trunk at the bulge, and taking out enough material to eliminate the reverse taper. Then I will clamp the two halves together and let it heal.

Your thought?

 

[erich_raudebaugh]

I have a tree with a slight reverse taper. I am thinking about splitting the trunk at the bulge, and taking out enough material to eliminate the reverse taper. Then I will clamp the two halves together and let it heal.

Your thought?

Pictures?

 

[Cajunrider]

Pictures?

Do we really need pictures? If we can split the trunk for bending, why can’t we split the trunk, take out a wedge and put it back together with better taper?

 

[erich_raudebaugh]

Do we really need pictures? If we can split the trunk for bending, why can’t we split the trunk, take out a wedge and put it back together with better taper?

You can certainly try. I just wanted to see if there's a better way. Extracting a wedge might be easier on conifers.

 

[19Mateo83]

I know it is possible to split the base of cuttings and air layers of certain species and create nebari flare. I guess anything is possible. Although it may be difficult to extract a wedge going with the grain

 

[Shibui]

Split and graft back works well on some species but maybe not so good on others, especially if they swell while healing.
You may need to split in 2 directions or the trunk will be wider on one side.

Some pointers to be aware of:
Needs to be tied tightly so the sides unite instead of pushing each other apart while healing.
While tied together the trunk will still be thickening. Swelling will occur above and below any ties and in between if there's any gaps. Fibrous ties like raffia will leave patterns in the bark as the trunk swells so smooth wrapping like wide tape is better.
Keep a close eye at the top and bottom. As soon as there's any sign of swelling remove the tape but it will probably need to be replaced because if not completely healed the edges can push the split apart again.

Split and join can work but there is always a chance of something now working as expected.

 

[Brian Van Fleet]

What kind of tree is it? Some heal better than others. The last thing you’d want is to replace a slight reverse taper with a larger scar.

 

[Cajunrider]

What kind of tree is it? Some heal better than others. The last thing you’d want is to replace a slight reverse taper with a larger scar.

It is a rainbow eucalyptus.

 

[LittleDingus]

It is a rainbow eucalyptus.

Then my experience is "no".

I don't find rainbow eucalyptus pliant enough to be able to split and remove material in a way the cambium can be rejoined. Plus, mine bulge around healing wounds...which would defeat the purpose, no? I would expect any kind of lengthwise split on thicker branches to just keep right on splitting...

They do layer really well...at least while youngish...if that's an option. Mine are only a few years old but I get good amounts of roots in a few weeks when layered in summer. I've read reports that older wood will not backbud or layer easily, though. Many articles I've read suggest after 5ish years the cambium looses the ability to easily differentiate and so can't form growth buds or roots anymore.

 

[Cajunrider]

Then my experience is "no".

I don't find rainbow eucalyptus pliant enough to be able to split and remove material in a way the cambium can be rejoined. Plus, mine bulge around healing wounds...which would defeat the purpose, no? I would expect any kind of lengthwise split on thicker branches to just keep right on splitting...

They do layer really well...at least while youngish...if that's an option. Mine are only a few years old but I get good amounts of roots in a few weeks when layered in summer. I've read reports that older wood will not backbud or layer easily, though. Many articles I've read suggest after 5ish years the cambium looses the ability to easily differentiate and so can't form growth buds or roots anymore.

I've done multiple air-layers on this tree in the past few years. The slight reverse taper came from the excessive swelling from healing after I cut away a major branch.

 

[LittleDingus]

I've done multiple air-layers on this tree in the past few years. The slight reverse taper came from the excessive swelling from healing after I cut away a major branch.

Yep...mine do the same: swelling to heal over a wound. I would expect the same from splitting the trunk: swelling to heal over a wound. Except that I'm not sure how easily the split can be managed so that it _can_ heal over.

Please post back if you try it! I'd love to see it work out for you.

 

[Shibui]

The slight reverse taper came from the excessive swelling from healing after I cut away a major branch.

I suspect that gives you the factors you need to make the decision but if you have the trees available and the drive to explore possibilities I'd be keen to see the results - good or bad.

 

[Cajunrider]

Here is the plan. I am cutting out a 6” long and 3/8” wide at the center. Then it will be filled with Titebond 3 wood glue and squeezed back together with hose clamps.

 

[Crazy Diamond]

I would try first to graft a branch in the base and let it grow to thick up the trunk, that method you planing is very drastic in my opinion for a inverse taper is not that bad in the first place

 

[TN_Jim]

careful of getting glue on the cambium to keep good clean cambium to cambium reconnection.. what are you using to make the cut?

 

[Cajunrider]

I made the cut with a vIbratory saw with a half moon blade. Tested to confirm I could squeeze it together. Then I filled the slit with JB Weld kwikwood and squeezed it in with 2 C clamps with plywood as cushion. I trimmed off the excess and filled the old scar. It looks good now. I will leave the clamps on for a couple months.

I didn’t use the Titebond 3 as planned because I thought the glue would run out before I could squeeze it tight.

Doing it this way I have no glue on the cambium. The epoxy was just in the woody trunk. Damage to the cambium was minimal.

 

[Leo in N E Illinois]

Engineering may have solved the problem. Interesting fix, hope this works.

Myself, I would have left it alone. Inverse taper is often a "red herring" focused on needlessly, or more so than necessary. If one can grow out a trunk to add an additional 25% to 50% to the diameter of the trunk, almost always inverse taper issues will disappear. Even adding as little as 10% increase in trunk diameter can minimize visual impact of inverse taper. Grafting a branch below or in the zone of inverse taper is definitely a proven fix, as is the crossing your fingers and praying for a well placed back back bud.

A surprising number of exhibition trees have minor inverse taper on a trunk or branch, inverse taper should not be viewed as a "fatal flaw".

But if you can increase the diameter of the trunk, inverse taper is usually an easy issue to fix. Minor cases are easy to ignore. Bad cases, especially when cased by graft unions are difficult to fix.

 

[Cajunrider]

Engineering may have solved the problem. Interesting fix, hope this works.

Myself, I would have left it alone. Inverse taper is often a "red herring" focused on needlessly, or more so than necessary. If one can grow out a trunk to add an additional 25% to 50% to the diameter of the trunk, almost always inverse taper issues will disappear. Even adding as little as 10% increase in trunk diameter can minimize visual impact of inverse taper. Grafting a branch below or in the zone of inverse taper is definitely a proven fix, as is the crossing your fingers and praying for a well placed back back bud.

A surprising number of exhibition trees have minor inverse taper on a trunk or branch, inverse taper should not be viewed as a "fatal flaw".

But if you can increase the diameter of the trunk, inverse taper is usually an easy issue to fix. Minor cases are easy to ignore. Bad cases, especially when cased by graft unions are difficult to fix.

Admittedly I was simply a bored engineer and wood worker who wants to tinker with trees while I procrastinate on more important matters.

 

[LittleDingus]

Engineering may have solved the problem. Interesting fix, hope this works.

Myself, I would have left it alone. Inverse taper is often a "red herring" focused on needlessly, or more so than necessary. If one can grow out a trunk to add an additional 25% to 50% to the diameter of the trunk, almost always inverse taper issues will disappear. Even adding as little as 10% increase in trunk diameter can minimize visual impact of inverse taper. Grafting a branch below or in the zone of inverse taper is definitely a proven fix, as is the crossing your fingers and praying for a well placed back back bud.

A surprising number of exhibition trees have minor inverse taper on a trunk or branch, inverse taper should not be viewed as a "fatal flaw".

But if you can increase the diameter of the trunk, inverse taper is usually an easy issue to fix. Minor cases are easy to ignore. Bad cases, especially when cased by graft unions are difficult to fix.

I agree that growing out the trunk tends to lessen the visual impact of inverse taper. Unless, of course, there is something continuing to generate the bulge...a branch, a burl, a healing scar, etc...

 

[Bonsai Nut]

If one can grow out a trunk to add an additional 25% to 50% to the diameter of the trunk, almost always inverse taper issues will disappear. Even adding as little as 10% increase in trunk diameter can minimize visual impact of inverse taper.

^^^ This. The first thing I thought when I saw your photo was not "oh look inverse taper". It was "what is going on in the upper part of the tree such that this wound did not heal?" Also, without seeing the nebari, I'm not sure I'd be too worried about the trunk yet. Uncover those roots so you know what you're working with. You may end up deciding that a formal upright is not the best form for the tree - in which case trying to work towards a stove pipe straight trunk may not be your goal.

HOWEVER... commenting simply on the technical aspects of your work I would make sure that your initial carving leaves a concave space to account for the inevitable bulge as the scar heals. As far as I'm concerned, an epoxy filler works against this. If you were worried about fungus, I would have carved down the deadwood and then applied a clear penetrating epoxy - like what they use for wood rot on old houses. Interestingly, I have never thought about using custom wood vise faces - even though I have used them in the past for woodworking projects. I could see how you might be able to rout a semi-circular channel in a couple of blocks of wood and use them for your clamps/vises and it might yield better results than flat pieces of wood.

Regardless - make sure you let the top of your tree grow like mad so that you can create vascular demand that will cause the trunk to thicken. If the top of your tree isn't growing strongly, the trunk will only thicken very slowly, if at all.