# codominant stems



## boynature (Nov 16, 2005)

just wondering what everybody's opinion is on when is a co-dominant stem to large to be removed. I'm talking about trees with V-crotches that could someday split if they are not either braced or removed. 9,10 inches?


----------



## Stumper (Nov 16, 2005)

In my professional opinion, such crotches actually exist. Some of them fail. Many do not.  :angel:

When they are under 6" diameter I frequently advise removal of one side.(Actually this depends upon species-If it a peach or plum that is never going to be very large or tall then this is much less important than a maple that is heading fro 80feet and hanging over a house). When they are 9-10 inches It gets more dicey-remember-most included crotches DON'T fail-the potential for failure is simply statistically higher.


----------



## Tom Dunlap (Nov 16, 2005)

Start a subordination pruning program. The sooner you can chagne the relationship between the two from branch to branch into a stem/branch the stronger the union will be. As long as they're codoms they will grow at the same rate and push each other apart. Getting one to become a stem and increase the growth rate will allow a branch collar to form instaed of a weaker codom union. 

Reducing the foliage on one side by about 20-30% should get things going. You don't want to whack off the top of the subordinated leader. That's no better than topping. Make a reduction cut at the top and then do some thinning. When I;ve done this I try to clear away limbs on the sub limb that will compliment and encourage limbs on the dom limb to grow larger.

You're playing arbo sculptor here.

Adding a non-invasive cable is generally warranted to add some support to the weak union.


----------



## treeseer (Nov 16, 2005)

Righto Tommylop!

boy, post a picture and we'll talk more. please don't overdo the concern--at the ginter gardens in richmond va, the staff went absolutely nuts, removing half of every tight-angled fork. The butchery was awful to see. better to underreact, and reduce rather than remove.


----------



## John Paul Sanborn (Nov 16, 2005)

This is one of the times when Wolki would rant about dogma. Tight crotch, cut it out...

I have seen many stable large trees (many many silver maples) that have no problem surviving as included co-dominants. Subordination of one stem is allways a good first step, cabling may be needed, but this depends on how the tree moves near the union.

As Mattheck says, trees talk to us by how they add on wood. if there is a lot of asymetrical growth in that area, then adding something may be needed. If the moment of bens is farther up stem, then the tree has grown to accomodate the structure.

Then there is the study that Gilman did that shows that if the V crotch has no visisble seam to it then it is nearly as sound as a U crotch.

Cabling usually should be done from mutiple factors, if it's just one then other methods can reduce failur risks.


----------



## Lumberjack (Nov 17, 2005)

Stumper said:


> ...most included crotches DON'T fail-the potential for failure is simply statistically higher.




Can you explain that for me Justin?

If the tree is reaching maturity I would think that reducing the sub side would be poorly suited as the tree is slowing its growth greatly. Cabling is an option, I like cobra.

If the tree is young then subordinating is a great option, drop crotch reductoin and thinning.


----------



## Stumper (Nov 17, 2005)

Carl, I'll try-I kind of thought the statement was clear.Many trees form "bad" crotches. Included crotches are "bad" crotches because they are more prone to fail. Being more prone to failure does NOT mean that failure is inevitable. In fact most trees with tight/included crotches stand up and hold together for their entire life. What we notice however is that trees with codominant leaders and included crotches are the majority of the trees we are cleaning up after a storm. An examination of the wood and growth of such crotches makes it apparrent why they are weaker and more prone to fail. Because codoms with included crotches are statistically more likely to fail we 1. try to avoid planting such trees. 2. remove one leader when they are young. 3. subordinate one leader while still a juvenile tree. 4. cable mature trees . These treatments are advisable to mitigate the increased likelyhood of failure. What we sometimes forget is that "more likely to fail" and "most likely to fail" don't necessarily mean "likely to fail". Most of them stay standing without our help.

-I actually cabled a codominant Mulberry today. -I'm not against it I just like for us to think about what we do and why. :angel:


----------



## Fireaxman (Nov 19, 2005)

Where can I learn more about "Cabling"? 

A lot of very nice trees were topped out by Katrina, often leaving several very healthy branches below the break. I am guessing those branches will now compete for dominance, possibly leaving us with some pretty extreme examples of co-dominant stems. 

I know of at least one tree that was topped out in an earlier storm that is nicely symetrical and not at all unattractive (in fact the multiple stems provide a nice shade, highly prized in South Louisiana in the summer, I will try to attache a picture). So, my effort thus far, in low risk situations, has been to remove the broken top down to the first healthy limb and see what happens. Has anybody got a better idea? Would it be a good idea to "Cable" two or more healthy branches at the top to add strength?

Just hate to remove a tree that might stand a chance of a symetrical recovery at no risk to house or heavily trafficked areas. I have little experience or education in this, any advice would be appreciated.


----------



## Tom Dunlap (Nov 19, 2005)

The first place to start is to read a copy of the best practices for cabling. The ISA has the pamphlet for sale. 

There is information on the web but, like all web info, some is bad. 

Cabling and bracing has been talked about in depth on AS and the other arborist forums. If you look at this like you're taking a night class, the research won't seem like a daunting task. 

http://webboard.isa-arbor.com:8080/~ISA/search

http://tinyurl.com/7uj2b

http://tinyurl.com/bwk9t


----------



## Gopher (Nov 19, 2005)

*Talk to Guy...*

Another resource would be (regarding creative pruning due to storm breakage) to contact Guy Meilleur. He has written some good articles and has much practical experience in this area.

I agree with you Tom; this is my approach when a tree is younger and of course. looking at species, location, etc.

I have a bitternut hickory at home that I meticulously pruned three years ago, and now it has a codominant lead at about 20 feet. I am not going to touch the tree again. It has lots of space, and I'm going to let the lower branches touch the ground. If it breaks, I am going to leave the limb on it if still in the tree (if I think it won't be a safety issue.) Right now the tree is about 30 feet tall, and I have another larger hickory tree that I have removed deadwood (the kids swing is in it) and prune about every other year.

Hopefully my wife will allow me to leave the tree go as my own experiment. I'll try and remember to post pictures of both trees soon, and we can follow the progress of both.

Happy Thanksgiving to all.


----------



## treeseer (Nov 20, 2005)

yeah dave post a winter picture so we can see the architecture. you are right; hickories do not split codoms like ash etc.

fireax that is a beautiful tree and you are right it is a great candidate for cabling. The BMP's cost $5.

i met a lot of people at the urban forestry conferece from LA and mS. I asked what they advise on trees with >50% crown loss, and if heading cuts are ok. Got the standard answer; always go back to the next big lateral.

i asked the same question to 163 arborists at tci; 160 said yes heading cuts can be a good way to save damaged trees. those states need arborists now a lot worse than they need treecutters. fireax pm me if you want more info.


----------



## Fireaxman (Nov 20, 2005)

Thanks, Tom, I found the ISA pamphlet on the web with no problem. I had tried a search here on Arboristsite for "Cabling" and I was spending a lot of time looking through places where it was mentioned but where there were few details and gudelines. I'm not scared of research, but time is precious, and my dial up is slow. The ISA pamphlet looks like just what I need - also saw a lot of other good publications that I would like to have.

Treeseer - yep, thanks, I want more info. So many trees went through roofs down here that everybody seems to want to cut cut them all down. I'm thinking maybe the trees pushed a lot of the wind up high, over the tops of the houses, possibly saving many houses from worse damage. Where I spent the storm (surrounded by tall pines) we had probably 150 mph gusts over the tops of the trees, but the house I was in saw nothing more than (I am guessing) 25 mph. No broken windows, not even a shingle blown off the roof. Fortunately the trees that fell did not hit the house.

In Slidell, Eden Isle, Chalmette - places that had no trees - there are far more houses destroyed all the way to the slab or pilings. Of course, those places were also closer to the Southeast quadrant of the storm.

Anyway, after the "Removal and Cleanup" phase is over, I'm looking forward to something more constructive. Saving the remaining trees.


----------



## TheTreeSpyder (Nov 23, 2005)

Very good recommendations. Even if the tree doesn't collar the subordinate branch, and needs to be removed, it will be smaller wound. Keeping the low weight, gives wider trunk too; wide and low giving stability. All green saved, provides siphon through transpiration that keeps roots drinking up water and nutrients; also keeps tree machinery running freely at full steam.

CoDoms, make the tree oit itself against itself, instead of the house standing undivided. In codom the most leveraged angle of support is taken by the other half in branchings or as 2 separate tree units growing together. Codom also takes the shape from round, or sphere that is long on loaded axis, and makes a non-round; easily leveraged shape, that carries it's weight usually on the worst axis of support.







One of Wulke's points was that we watch out for horizontal codoms as the most leveraged and failure prone. But he witnessed that vertical codoms, didn't get exercised cuz of balanced vertical structure, then became easily hyper loaded in a few degrees and failed. For, the most leveraged is at horizontal. But the most increase in leveraged beyond the conditions you were groan at, is near vertical...

FireAxMan; just like in any battlefield littered with dead and injured; i think re-search is the best that can be gained; get out the camera! Show why the failures happened, and which ones would fail anyway in time. Only now all present themselves for group re-view like never before; the perfect classroom!

Included Bark Archive from Fl. Hurricanes of '04


----------



## Fireaxman (Nov 24, 2005)

Treespyder - I can get a pretty interesting picture of what I think was a dramatic failure of a co-dominate stem tomorrow if someone has not cleaned it up yet; but more of a mystery to me are the co-dominates that did not fail. They seem to be witnesses for John Paul Sanborn.

Of course, a lot has to be attributed to the caprice of the storm- downbursts and tornadoes did a lot of the damage in a seemingly random pattern - and I think the oak in my post of 11/19 was protected by its proximity to a lot of much taller pines (since by luck or grace it did not suffer a direct hit from a blown down pine). But it still surprises me that most of those crotches held up, especially a "Raccoon Nest" in the center of the tree where the original top broke out. It actually held water, and I would have thought it should have rotted out long ago. 

Therefor my interest - when (and how) to cable and when should I just not worry about it. I'll just have to post some picts before I start drilling any holes and see what you guys can tell me. 

Thanks John Paul when you told me something to watch for in quoting Gilman "Then there is the study that Gilman did that shows that if the V crotch has no visible seam to it then it is nearly as sound as a U crotch" (post of 11/16). Even then, isn't it interesting that the crotch in front survived with such a deep seam when the tree took enough wind to lose several seemingly healthy laterals? (Arrow) That crotch in particular is the one I would like to cable, especially since it threatens the power line.


----------



## Fireaxman (Nov 24, 2005)

*Codom Blown Off by Katrina*

Promised you a picture. Loblolly, about 30" dbh. Failure is about 30 feet up the stem. 

I sure have had to be very careful with the spelling on this post. An extra "n" keeps trying to sneak into my abbreviations.  

Anyway, the codominant stem was blown off by Katrina.


----------



## treeseer (Nov 24, 2005)

Pine codom failures are almost always fatal; the wood is so straight-grained, the wound is huge. I lost a 23" er taht was codom 50' up; the rest of the tree died soon after. Tuliptree and ash and red oaks are also bad for that; maples elms and white oaks much less so.


----------



## Old Monkey (Nov 25, 2005)

Tom or Treeseer, do you guys have any good picts or sketches of how to subordinate a codominant stem? I think I get what you are talking about but illustrations are helpful.


----------



## treeseer (Nov 25, 2005)

Yes, Gilman's is the best. what you want is at the bottom of the menu: Powerpoints, Pruning, Structural Pruning has a lot of images on proper subordination. Should be clear enough to satisfy any skeptic.

The section on Reduction has an unfortunate drawing of horizontal wounds made by tip-pruning a storm-damaged tree. Wounds should always be as vertical as possible. Also he looks for a "clean" trunk up to 20', which in some sites is way excessive. But these are nits picked off of what should be industry standard.

Dan yes I would not want to climb that split pine if there was another way to deal with it.
Fireaxman, Gilman's ppts are freeware; the pruning one should be shown throughout Katrina country.


----------



## John Paul Sanborn (Nov 25, 2005)

http://www.ext.nodak.edu/extpubs/plantsci/trees/f1055w.htm

The above is a link to a very good manual on farmstead windbreaks from NDSU.

A well planed windbreak ramps the wind up and over structures, one of the problems we have in urban/suburban areas is that we let trees grow tall, or clear out tall tree areas, but do not have any of the low growing trees on the edges to bring the wind up over the lrge trees.

Of course this is just one of many factors involved but an important one.


----------



## Redbull (Nov 25, 2005)

This link could be helpful in some co-dom situations http://www.treelink.org/joa/2000/may/05_BRACE_RODS_FOR_CODOMINANT_STEMS_smiley.pdf

I am curious though, when does a co-dominant stem justify using a bracing rod vs. just a cable, or both?


----------



## John Paul Sanborn (Nov 25, 2005)

If the union is visibly unstable then bracint is called for, per industry standards a cable should allways acompany a brace due to the change in moment of bend in the stem.

I have doen a few where the bracing was added for the customers piece of mind and they descided to forgo the cable. This was included in the contract that bracing was recomended and concidered standard.


----------



## Redbull (Nov 25, 2005)

So bracing is ALMOST always accompanied(sp) by cabling?


----------



## Fireaxman (Nov 26, 2005)

I'm paying more attention to the codominant stem failures now, to help me recognize where the remaining risks are. The failures are almost always deep V crotches with obvious seams, just as I'm sure you who are better educated would expect. If the crotches are smooth they seemed to have about the same chances of survival as any other top or large lateral. Thanks for telling me what to watch for.

Ive added Gilman's site to my "Favorites" and I can see I'll be spending a lot of time there. Thanks again!


----------



## TheTreeSpyder (Nov 26, 2005)

Other factors have entered the picture specifically down there. You have to look around and see if any structure, tree or otherwise that has wind block potential has come down. This would load the tree in question with more wind than ever previously. A tree community works to share these loads. If that structure (usually tree) was touching 'your' tree always or only part of the time (during extreme loading), it was probably giving support. The farther from the pivot of the ground, the more support.

So, if a nearby tree just came down, and they were touching; your tree just increased wind loading and decreased support in a single 'move'. This alone can cause problems. If it also has weaknesses/ codoms; those factors can compound on each other and give later failure.

If lots of water in ground recently, need to determine loaded axis of the tree, and make sure roots aren't pulling out of the ground opposite lean, and/or ground sinking on the lean side at base/pivot (where forces are double loaded). 2 trees groan together at ground is codom to me; each preventing the other's roots from gaining leveraged distance opposite the lean as 1 codom branch does to another. Also, each half trying to keep the other from being round/ giving levrageable axises; if anything giving the cross axis to the loading more leverage, just as codom branchings do. Also, pushing each other apart in later growth as codoms do. Then, plus possible soil loosened from rain around these codoms at the ground connection; to further compound failures, of codoms connected at ground level. 

But, after a while; you will have all survivors; with many of the sick and weak thinned from the herd. But always watch for changed conditions a tree is incurring; it's local history is important.


----------



## Fireaxman (Nov 26, 2005)

TheTreeSpyder said:


> Other factors have entered the picture specifically down there. You have to look around and see if any structure, tree or otherwise that has wind block potential has come down.



Yep. Thanks, and timely. And not just Katrina damage. Lots of people moving to the "North Shore" from New Orleans, lots of trees being bulldozed to make room for subdivisions.



TheTreeSpyder said:


> If lots of water in ground recently, need to determine loaded axis of the tree, and make sure roots aren't pulling out of the ground opposite lean, and/or ground sinking on the lean side at base/pivot (where forces are double loaded).



Very little rain since Katrina, actually a drought. But I've been using root pull as a guideline for removing ramaining weakened trees when necessary and I will watch the rains when they come (as they soon will, South Louisiana style) as per your advice.



TheTreeSpyder said:


> 2 trees groan together at ground is codom to me; each preventing the other's roots from gaining leveraged distance opposite the lean as 1 codom branch does to another. Also, each half trying to keep the other from being round/ giving levrageable axises; if anything giving the cross axis to the loading more leverage, just as codom branchings do. Also, pushing each other apart in later growth as codoms do. Then, plus possible soil loosened from rain around these codoms at the ground connection; to further compound failures, of codoms connected at ground level.



Gotchta. A little off the thread, but your comment on trees grown together brings it to mind. What do you think about this? 

I've got a 14" sweet gum sub-dominant to a 24" white oak and the trunks are only 12" apart. The oaks are usually very shallow rooted in our heavy clay soil, but the sweet gums are often deeply rooted (sweet gums often drop frequent "Tap" roots off of extensive shallow surface roots, I've tried to dig several stumps out of the ground and it's always been a fight).

I have left the sweet gum next to the oak hoping the deeper roots of the sweet gum are tangled in the oak and will help to hold it up. Is this reasonable in your experience? The oak/sweet gum combo is only 30 feet West of a house, and it has lost windbreak (1) from a couple of other nice oaks that fell away from the house in Katrina and (2) from trees removed for a new subdivision 150 feet West. The oak suffered 50%+ canopy loss from Katrina (one side of a codominant stem, but above the crotch, and some additional branches) but it was a beautyful tree and good shade for the house. Hate to lose what's left if it has a chance. 

Thanks for the help.


----------



## treeseer (Nov 27, 2005)

Fireaxman said:


> (sweet gums often drop frequent "Tap" roots off of extensive shallow surface roots,
> I have left the sweet gum next to the oak hoping the deeper roots of the sweet gum are tangled in the oak and will help to hold it up. Is this reasonable in your experience? The oak suffered 50%+ canopy loss from Katrina (one side of a codominant stem, but above the crotch, Hate to lose what's left if it has a chance. .


I would hate that too. Prune the sweetgum away form the less vigorous oak. Yes the roots of the gum may be stabilizing the roots of the oak. The "Tap" roots coming off laterals roots are called "sinker" roots. Many sp. do this.


----------



## Gopher (Nov 27, 2005)

*Good info arborists - pictures of young split to monitor...*

For some reason (Ma Nature), this hickory of mine split, and actually has a long lateral near the top reaching to the east. As I stated, I am not going to prune this tree anymore, just let it do its thing.

The other one is the parent to the first one; I have a swing in it, and the boys spend lots of time in this area, so I get in it at least every other year.

Maybe not super scientific, but a small case study...

Everyone have a good Monday; probably no climbing here in Wisconsin - very, very wet...


----------

