Maple knot hole risk and how to fix?

[keithonline]

I have a large two trunk maple in my back yard, I believe it may be a black maple. I noticed a knot hole about 14 ft up that I inspected. It appears to be about 9" inward, 7" wide, and about 17" deep (along the axis of the trunk). The tree is leaning away from this hole. The diameter of the tree is about 18-19 inches. I'll post some pictures.

My question is this. First, is this tree sound? I vacuumed out the opening. It was full of dirt, but not much rot. Secondly, if it is sound, how should I fix the opening to keep it from rotting further. I put roofing tar in a smaller hole on this tree once, but this one is much bigger, and I'm not sure if that's the best action.

Thanks in advance.

 

[treeseer]

Nice pictures. Roofing tar won't help. If the cavity is 9" x 7", then it may not be a huge hazard. The way to slow rot is to boost tree vitality. mulch around (not on) the trunk, fert spring and fall. If the crown above is heavy, you can have an arborist lighten it up.

 

[arboristman]

take a pic of a leaf close up.looks like a sugar maple.
call your local tree service and have them install a cable,and lighten up that side.be sure to hire an arborist.he will know what to do.but for sure an arborist is needed.i would also have them fertilize the tree.

 

[Dan R Porter]

Hmmmm...

It looks from your pictures that it is hollow down the trunk some, how far down/up does it go? If it goes down a ways I would remove it since it hangs over the house, then replace it ASAP.

 

[arboristman]

why? thats a small hole if its a sugar.

 

[Sprig]

In my humble opinion I think that that side of the tree is a major accident waiting to happen. My reasoning is that the hole is over 12ft up in the trunk, has a large canopy above it, cannot be stopped ( no tar, cement or other foolish things), and undermines the over-all structure of the tree. As well it seems to be leaning in the direction of buildings etc.. Were it off in a corner I probably wouldn't be inclined to give it much thought, but because of where the hole is, despite the obvious structural growth going around the hole (I would guess that is called a 'callus'?) I do not think that is enough to give integrity in the long run, eventually I think it is going to fail no matter if it is cabled to the near brother or not. It just doesn't seem like a good spot for a hole, too high up in the trunk and a point of great stress in winds etc.. I am sure I shall stand corrected in this but I am thinking that the height of it (the hole that is) is like having an open knot in the middle of a long board. A very weak point. I see by the pics that it does have growth growing around the outside of the cavity, will this give it the strength it needs to survive for long? I am curious too. My 0.02$ worth (maybe worth less, dunno lol), it seems like this goes back into another thread regarding 'risk assessment'. Can it be left to do its own thing or are there other considerations?



I have another small q here, is/would it be possible to simply put a cover over the hole to stop extra water getting into it, preventing additional rot and giving the tree a chance to put thicker growth around the hole, is it too big for this, would/does this sort of strategy work or been tried?

 

[treeseer]

Dan, how does the length of the cavity affect strength loss?

Sprig, the callusing you see turns into woundwood, which is 40% stronger than normal wood. And no, keeping water out won't stop rot. nOt a bad idea, but the focus belongs on boosting tree health, and lightening the load by cleaning the crown.

 

[rebelman]

Tough call. Good points all around. Yes, lightening the load and cabling would be good, but I would probably remove the entire side toward the house. The remaining section should be fine, and always lean away from the house. Mulching the root zone is standard prescription too. Usually ignored, very important.

 

[treeseer]

I would probably remove the entire side toward the house. The remaining section should be fine, .

reb that's the worst idea that you ever had. The larger trunk may have an even larger cavity, unseen. Please get a copy of the BMP's and findout more about reduction pruning before you go whacking off big trunks.

You wanna talk about big cavities? What's gonna happen to the wound you make when you lop off that whole trunk?opcorn:

 

[keithonline]

More info on tree

As far as a target goes, it appears it would land between my garage (in the picutre) and the house, right on the driveway. Crushing my boat, presently in the picture which would be fine as long as I'm not in it.

The suggestion that putting tar wouldn't help confuses me. I've read in another post that rot is from an aerobic process, so water will actually slow the rot. I know water in wood isn't great, so tar seems like a good choice to both keep out water and seal out oxygen. Is there a commercial product that serves this purpose? Does the strength change much between a black and sugar maple? It may be a sugar. I'll send a pic of young leaf it makes a difference.

I like the idea of having an arborist look at it, and keep the tree health to improve healing. Its our only tree in the back yard so I want to save it. A trimming seems to make sence too.

Thanks for more input. Any recommendation for an arborist around zip 06488 (western CT)?

Keith

 

[Dan R Porter]

Cavity length

The legnth of the cavity does affect strength. If it is all the way up the tree it is lighter wieght, if not it is heavier, and the whole tree could be hollow for all we know. Just better safe then sorry in my opinion.

 

[Dadatwins]

The suggestion that putting tar wouldn't help confuses me. I've read in another post that rot is from an aerobic process, so water will actually slow the rot. I know water in wood isn't great, so tar seems like a good choice to both keep out water and seal out oxygen. Is there a commercial product that serves this purpose?

Getting an arborist to look at is best idea, lighten the load at the top a bit if the wood is determined sound, cutting off the whole piece last resort, maples do not close large wounds well, as you can see first hand. Putting in a cable would add another wound by drilling holes, maybe a non-invasive cobra cable, but I don't think the expense is necessary. As for keeping water out, I have filled a few cavities with expandable spray foam, offers no structural help, less messy than tar and once dry stays where you put it, just keeps out water and nesting critters, bees, and climbing rodents.
Keeping water out good idea as cavities like this become mosquito breeding grounds. Have someone look at it first before filling it. Good luck.

 

[keithonline]

Update

As far as the depth goes, I did say. It's 17" along the axis. Therefore the "whole thing is not hollow". Thanks for the imput about foam. That's helpful. Foam is probably closed-cell so it will probably seal out air. That seems to make the most sence.

If I have not given enough information to make a recommendation or I need to add additional info, let me know. Blabbeing about useless suppositions just to hear you head rattle is not very uselful, and makes this whole site less valuable. If you need more info to make a professional opinion, that's fine. Let me know and I'll gladly do so. I think that's what most people reading these sites are looking for.

Treeseer, (and others), thanks,

Keith

 

[keithonline]

Crotch rot with roots?

Another question. Differnent topic, same tree. Where the two trunks meet, I noticed some debris, rotting wood, etc. I vacuumed it also. Not much there. But I got to a point where I saw what looked like fine roots. They're bare now, and I was wondering if they are the tree's roots making "root" in the dirt in the crotch. I don't know much about tree anatomy or growth, and I was wondering if this is a normal process. As the tree grows, how does it "merge" at this V area? Is rooting normal if debris is present, and if I want to do my best to keep the tree from splitting at this tight angle point, should I do something to keep water and debris out?

Just something I never really considered before. I know a tree will grow "into" or "around" something, like if a rope is wrapped around it. But how does a tree grow into itself, especially if debris is there?

Keith

 

[trees4est]

To find an arborist in your area, go to the ISA website http://www.isa-arbor.com, there's a link for "find a certified arborist", it gives you different criteria for searching, including zip codes, I think. Though you might want to broaden your search a bit to not limit your options. A cavity of that size does compromise the structure of the tree, it does make a weaker spot on the stem. Doesn't mean it's about to blow or anything. It's hard to tell even with your thorough photos about what forces are exerted on that leader, and it's impossible for anyone to tell you it is "safe", though they might be able to tell you more about your specific situation that you can make a call from. Ultimately it's about what level of unknown risk you are willing to live with.
About your incidental question, it does look as though the forks between the stems may be included (basically a sharp "v" fork with bark wedged between stems) which is also a structural weakness. Like the cavity it means something, but it's not necessarily the end of the world.
Cavity filling. Ah, you'll get many opinions on that. My personal opinion is forget it.
The bark looks kinda like silver maple, maybe Norway. Just as a guess.
Like some other guys said- call a few arborists, see what they say. You'll have to use your judgement on them.

 

[treeseer]

are the tree's roots making "root" in the dirt in the crotch. ... Is rooting normal if debris is present...? how does a tree grow into itself, ?

Roots grow wherever the right stuff is. I find roots in cavities a lot, and in forks frequently. Taking debris out of the fork makes some sense; hard to say without seeing the fork up close. Best thing you can do for the fork is to lighten the top, and cable if the defect is severe.

I know a guy in zip 06277.

 

[rebelman]

To me that defect is fairly severe. I wouldn't want that leaning, hollow side trunk over my house. Sure it's a garage, noone sleeps in there do they? Tree seer says there may be another unseen hollow in the other side, but this is true of all trees on the planet. Maybe it was a bad idea to remove the codominant stem, maybe not. I'm not so sure cabling and reducing a seventeen inch diameter with a ten inch hollow over a house is such a great idea.

 

[treeseer]

a seventeen inch diameter with a ten inch hollow over a house

First, check the camera angle, and the poster's words--it's really over the driveway.

Second, 17" - 10" = 7" holding wood. Much of that is woundwood and reaction wood, 40% stronger than normal wood. the tree has been adapting to the loss of strength due to this hollow for some time.

nOthing wrong with erring a little on the side of safety, reb, but imo the primary solution is restructuring the crown.

 

[Kneejerk Bombas]

Here's what I would do, if this were my (or my client's) tree:
Climb and inspect the entire tree.
Install a cable. This would help prevent breakage at the hollow and the narrow crotch. And if it did break, it should be suspended by the cable, safely above the boat.
I'd opt for a Cobra brand synthetic cabling system, which is basically a strong rope with a shock absorber. It gets installed 2/3's of the way up from the bad spot, to the top of the tree. It runs from the weak side to the strong side.
While I was up there, I would look at the structure of the weak limb and remove small branches that would help lighten the load, but more importantly, those that had the highest exposure to wind loads.
The total removed would be less than 25% of the foliage of the limb. In the back of my mind at every cut, would be the fact that the foliage I'm removing is what makes the food that grows that woundwood Treeseer eluded to. So, I'd minimize the cutting to what seemed absolutely necessary.
Remeber, leaves make food, not roots or fertilizer.

Next, I'd concentrate on the soil environment. The area under the "dripline" would get mulched.
Start by cutting the lawn as low as possible. then cover the area with newspapers. This will help keep weeds down. Next add composted cow manure, which you can buy at most any garden center for a couple bucks a bag. About 15 bags will cover the area.
Finally, add about 2" to 3" of decorative wood chips. Don't go deeper. These will slowly break down and turn into compost, to feed the tree. They will also help keep the soil moist, moderate temperatures, make weeding easy, keep traffic away from the roots, protect the trunk from mowers and weed eaters, and look good.
The tree can also be helped along by watering during dry spells. If you go a week without rain, run a sprinkler on the chipbed for a half hour or so, then don't water again until the soil drys out.
Other than the compost, do not add fertilizers. Unless your fertilizing is based on a soil test, you're most likely hurting the mature tree's chances of recovering from the trunk injury.
Also, do not worry about water, ants, roots or animals getting into the cavity. The tree has built in protections against these kind of things, and studies have only debunked any claims of efficacy.

 

[treeseer]

Great advice! Mike, your recommendations on pruning are spot on. After all these years of we agree.



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