Using PL-Premium (construction adhesive) to fill holes in tree trunks

[Sum Guy]

I've found that PL-Premium (polyurethane construction adhesive) to be a very durable, strong and water-proof glue for wood for all applications (indoor and outdoor).

I just filled a couple of holes on the trunk of a silver maple that have been formed by some sort of insect over the past maybe 6-months. The hole is in the face of a limb-cut that I made a few years ago and had painted with black pruning paint. I was surprised how deep the "rot" was - I was able to push the plastic dispensing nozzle of the glue cartridge all the way into down into the trunk.

So even though I've already done it, I'm wondering if anyone knows how well this stuff works at filling holes in tree trunks to prevent further rot and allow the tree to grow over and eventually cover exposed heartwood.

[JimR]

Using pruning paint is not a recommended procedure because it traps moisture in the cavity and encourages rot, such as you found. It's better to leave this type of wound alone and let the tree heal itself. (Palms are a different matter . . . as monocots they don't heal . . .)

[Sum Guy]

This was insect-induced rot.

Moisture could not be trapped - this is a vertical surface we're talking about - roughly a circle about 3" diameter.

Wood protected by oil-based coatings tends to weather better than left untreated.

It's funny how pruning paint is somehow not good for exposed wood, yet you see people applying coatings to their decks and other exposed wood all the time.

I've also found that pruning paint is good when applied to the top surface of horizontal limbs near the trunk that squirrels tend to tear apart - dammage that most people don't see because it's over their heads. The squirrels don't find the bark so tasty with the paint.

[Evan]

Decks and other exposed wood which has been cut and milled into lumber is no longer alive...

Wood on a tree is still alive and growing...

It is best to leave tree wounds alone and allow them to heal naturally... Exceptions to this logic are rare...

~~ Evan

[ransley]

what insect makes a hole 3"

[Jim Elbrecht]

What insect *induces* rot? All the wood eating critters I know about show up after the wood is dead.

Those decks and stuff are *dead* wood. Presumably you cut the branch off on a live tree. The tree will bleed and heal the wound much better without being insulted further by some foreign sealer.

I prefer to apply lead directly to the squirrels. But I don't think squirrels do any damage to hollows in trees

Jim

[JimT]

Decks and other exposed wood which has been cut and milled into lumber is no longer alive...

Wood on a tree is still alive and growing...

It is best to leave tree wounds alone and allow them to heal naturally... Exceptions to this logic are rare...

~~ Evan

====

Live Oaks maybe an exception. The pruners here are adamant about using paint to prevent Live Oak wilt.

[jamesgangnc]

Actually the wood inside the tree is dead. Only the outer layer of a tree is alive. But generally it is best of you just let the tree bark grow over the wood. The black tree paint inhibits that and does trap moisture. It will eventually heal it's self but it will never repair the rot inside. If a substaintual part of the truck has rot in a spot it is now weakened. If that is the case and the tree has the potential to land on your house then have it removed. Lots of times if you look at trees that have broken off during bad storms you see that it was at a spot like this. Used to be people would clean out holes like this and fill them with concrete. Don't know how well that works. It's possible your holes were made by wood bees. Were they about a 1/2" round and so well done that they almost looked like a drill had done them? Wood bees will go a long way into wood.

[Sum Guy]

The exposed inner heart-wood of the tree has a circular profile and is

3" in diameter, and it oriented vertically with respect to the ground. This is where a secondary trunk had been, which was cut maybe 2 or 3 years ago.

This circular area was sprayed with pruning paint last year. The surface was solid and intact at that time. The bark is growing nicely around the perimiter of this area (this is a silver maple). I have two such similar cuts on a sugar maple - the exposed area was even larger (4 or 5") and painted them soon after the cut was made. This was about 5 years ago. They are 75% covered over now by the growing bark, and they remained solid (no rot, holes, fissures developing in them).

Getting back to the silver maple, at some point this year I noticed the appearance of some cracks or voids on the cut surface along with what looked like sawdust shavings around the crack. Yesterday I shoved the plastic dispensing nozzle of a tube of PL Premium deep into the main crack (it went in all the way - I wasn't expecting that) and I pumped the crack full of glue.

[Sum Guy]

By rot, I mean the development of cracks, fissures, cavities and holes caused by the removal of wood caused by insect activity. I guess I used the wrong term.

When you cut a large limb off a tree, the inner wood that you expose

*is* dead. The only living part of the trunk is the bark.

If the cut is large enough, it will expose dead wood, and that wood is vulnerable to insect dammage and weather-related dammage (actual rot, fungus, etc). This dammage may set in before the tree has enough time to grow around and cover the exposed surface with new bark.

[Marty B.]

Silver maple is a garbage tree. The wood is soft because they grow so fast. Surely you've noticed how they break during wind, and how fast those things grow. Why you would want to save the thing is beyond comprehension.

[Sum Guy]

Pruning paint does not inhibit bark growth over the exposed cut surface, and it does not trap moisture because the exposed heartwood quickly dries out once exposed to the air after it's cut, and any moisture deeper in the wood under the painted area will find other ways to move within the tree.

I know that, but I'm thinking that the glue will (a) kill whatever organisms/insects are in there causing the dammage, (b) fill the voids to prevent re-introduction of similar pests, (c) perform mechanical bonding and return strength to the dammaged area (in a way that other simple fillers wouldn't).

We call them carpenter bees, and they have drilled those perfectly round holes in the side of my eaves under the gutters in previous years before I replaced the wood and covered them with aluminum siding. I have lots of other lumber that sits in my back yard (remnants from other projects) but I've never seen these bees go after that wood, nor the exposed eves of my shed.

In the case of the fissures on the exposed cut surface of the silver maple, these are not the perfectly round holes made by carpenter bees.

[jamesgangnc]

Seems like that would be ok. It's going to be a weak spot even after the tree grows over it. But there's nothing you can do about that.

[Sum Guy]

As has already been mentioned, the wood inside a tree under the bark is actually dead wood. The only difference between it and the lumber you buy at Lowes is that the wood in the tree hasn't been milled.

If the exposed surface is large enough, the wood can rot and/or be attacked by insects before the tree has a chance to grow bark to cover it.

I think that different climates can be more problematic than others. In the north-east and great-lakes area, you have a shorter growing season (takes more time to cover exposed cuts with bark) and lots of humidity and freeze-thaw action in the winter, both of which is hard on untreated exposed wood.

[Sum Guy]

I have lots of trees in my large back yard, and this tree is near my back fence, it's about 30 feet tall, and provides privacy between me and the apartment building across the street behind me.

If I could go to a big-box building store or nursery and bring home a 20 or 30 foot mature tree of my choice and plant it exactly where I wanted it, like I can do with a flag pole or a mail box, then sure we'd all be doing that.

But trees don't grow on trees (so to speak). We can put up skyscrapers in only a year or two, but it takes decades for a tree to grow to the size that you want them to be. Until we can easily replace mature trees with other mature trees in a few hours or days, I don't think I'm going to be cutting mine down because it's not exactly the tree I might want in a given location.

If you ask me, we need more trees and fewer people on this god-damn planet.

[RicodJour]

The non-cambium layers of a tree's wood is dead, but not dead in the way animals die. Wood is pretty stupid, pardon my French - it doesn't _know_ it's dead. So it keeps on trying to fulfill its function which is to transport water. It will do this whether or not it is still in tree form or built into a deck or whatever.

Any coating put on a tree that is intended to protect it from water will interfere with the tree's eons-long evolution of its healing process.

It is important how, when and where to prune limbs. Improper pruning will not allow the tree to heal.

"Prune maples during their dormant period when you can see their shape and branches. Pruning in late fall or early winter removes wood when pests and diseases are not likely to thrive on the green wood." "Avoid making "flush" cuts that destroy the bark collar or "stub" cuts that leave exposed wood beyond the collar that may be susceptible to disease."

Murphy's Law predicts that the most 'important' trees will suffer the most egregious fates. If you need a tree for privacy, don't expect it to be around forever.

A general overview of the Silver Maple:

's not a forever tree, it has 'issues'.

R

[Jim Elbrecht]

-snip-

Not the OP-- but here's why I want *my* silver maple. It is 150 years old & has more character than I can afford to buy. It also shades the back of my house and my patio.

It is messy-- it drops limbs, seeds, buds, and leaves during the year.

But it also provides a few gallons of sweet maple syrup when the spirit moves me to tap it.

Jim

[RicodJour]

How long does it take to boil it down, and where do you do it?

R

[Jim Elbrecht]

Forever- and in my kitchen. I haven't done it since I installed a humidifier, so the extra humidity has been welcome.

I set it on a slow boil for a couple days-- It doesn't need any attention until it starts to color up a bit. [Then things can get tricky fast- I never had problems with boiling 100gallons of sap adding too much moisture to the house-- but on a couple occasions it went from syrup to sugar to carbon while I wasn't paying attention.

*That* stinks up the house.]

I probably use one burner on the stove for 12 hours a day for 2-3 weeks to yield 3-4 gallons of syrup & a bit of sugar candy. [wild ass guesses - I haven't done it in a few years.

Hmmmm- just thought of another use for my new Bayou burner-- I might do some sap next spring and just finish it in the kitchen.

Jim

[Sum Guy]

Again you are talking about the recently-dead layers (xylem) immediately under the vascular cambium. Under that layer is the secondary xylem, which no longer conducts water and is used to store waste products (in some cases - resins). The secondary xylem is also known as heartwood, and this is what is used to produce modern dimensional lumber.

Both the Xylem and heartwood (secondary xylem) are composed of dead cells. They are structurally intact, but they no longer respire (ie - they are not biochemically active).

When a limb of sufficient size is cut near the trunk, you will be exposing this dead heartwood region, which is incapable of protecting itself against weather, sun, fungal and insect dammage. Only new cambium growth over the exposed area will eventually provide this protection.

Not really. Heartwood is not a good conductor of water. In fact, it is necessary that the heartwood not contain significant amounts of water, since that would dammage it during freeze-thaw (expansion-contraction) cycles in the winter.

Heartwood is not normally exposed, so the application of a coating to it will shield it against sun, rain, humidity, fungal and insect attack. Normally the cambium and bark performs this function.

Yes, there is a correct cut-line to use for the most optimal removal of a limb from the trunk. But we digress.