please explain co-dominant leader

stevefisch

In a separate thread I have been asking for advice on an okame cherry tree I bought (Okame Cherry: bad branching structure?). I am trying to understand if the tree has structure problems.

apparently the tree has a co-dominant leader. I can see where, about half way up, the trunk splits.

But i don't understand how problematic this is. Do okame cherries always do this? I have been looking at trees around town and seems like most have trunks that split. Are all of these co-dominant leaders? Or does it have to be a certain angle to qualify (and be a problem)?

In my okame, the angle is pretty tight, but the crotch, at this point in its young life, is a U not a V. Does that matter?

When I bought the tree I asked the nursery guy if there were any problems with the tree's structure. He said there were none (hmm!). Should he have pointed this out to me?

How common are co-dominant leaders and are they grounds for complaining about a tree to the nursery?

thanks,
steve

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Eric Frei

Co-dominant means exactly what it says.

Two dominant leaders, usually about the same diameter and about the same height.

Now just because they are co-dominant doesn't mean they are all bad. Depends on whether or not there is included bark and how acute the angle is, plus of coarse tree weighting, canopy bias etc etc

refer ......

V and U shaped Crotch Strengths, included bark| codominant stems etc

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stevefisch

How can I determine if my tree has included bark?

Can you tell from the photos?

Thanks again,
Steve

glennak

This is what included bark forks do. There is bark in between the 2 trunks that are pushing on each other as they get thicker they push harder and harder to one day it pushes itself apart and the wind is usually blamed.
Co-dominate stems can have included bark then they are very bad if not then theyjust are not perfect unions. If there is a bit of a saddle in between like yours not to bad.
To understand the trouble you need to understand how trees grow.
At the start of the growing season the small twigs start to grow then latter branches and last of all the large trunks (this was not known till the 70's) At branch unions the branches grow wood over the trunk and latter in the season the trunk grows wood over the branch wood. It is these overlapping layers that hold branches on. Now co-dominate stems grow at the same time so no over lapping layers therefore not as strong.
What I often do is reduce one leader to a side branch and let the other be the leader so it gets larger so the overlapping can occur in future years.
Hope this makes sence to you.

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Eric Frei

Glennak,

That ironbark that you have shown a pic of, is that in Melbourne?

What have you got that ones ssp name as?

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Garry Brockley

I would have that as a Eucalyptus Crebra (narrow leaved iron bark) but the buds and leaves would help

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glennak

Yep it's in a park in Melbourne and it was a bit slack of them to leave it to split like that. Its a Eucalyptus sideroxylon Red Ironbark. Many years ago my old boss and I were driving through a box ironbark forest in central victoria and decided to do a survey. We found that 3/5 ironbarks had included bark forks about the same as the ironbark street trees planted in Ballarat at the time. No better than Euc nicholii but at least Ironbarks are stronger.

Eric Frei

They're notorious up here for inclusions also. It's almost a genetic thing. The tree doesn't have the odd one but almost all unions are included bark co-doms.

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Apocalypsse

Which park is it?

glennak

JE Moore Park in Reservoir

TrevMcRev

I agree on Red Ironbarks. Almost everyone you see has really bad acute V unions, usually with included bark to boot! Very common to split. Ideal to cable.

glennak

Much better to chop one off early and prevent them from forming rather than to cable.

stevefisch

Given that my Okame Cherry has a codominant leader, and that one of the leaders has its dominant branch pointing to the interior of the tree, i am thinking that i need to do some strategic pruning, possibly attempting to make this leader be less dominant, and losing that inward branch

the tree was planted a week ago, in a burlap root ball.

i read somewhere that the tree is struggling to produce new roots so it might be a bad time to do any significant pruning.

- how do i train a leader to be less dominant without hurting the tree and making it grow suckers?

- should it be a slow process over a few seasons?

- should i wait till winter (it is summer here now)?

thanks,
steve

glennak

No don't wait do it now so the other can grow. If you cut less than a 1/3 it shouldn't sucker a lot. Don't leave stubs and remove any suckers before they get too large and you shouldn't have any problems even if you take more than a 1/3.

TrevMcRev

Of course, i were referring to already mature ones that should have had that done 20 years ago

jmcg.insight.gardens

Hi Stevefisch,

you spent good money on that tree by the look of it, the answer to your question is, if your not sure of this point, you could compromise the health of the tree, I've seen too many improperly pruned cherries, they rot eventually at the pruning site, not pretty.

If you feel that you would like to help the tree to gain the best form, spent that little bit more, and invest in some professional help.

Glennak is right in suggesting it should be done now, my humble suggestion, protect the money you have obviously spent and get in someone that will bring the tree to it's best potential.




Julie

Eric Frei

Subordination is also an option, and in a young tree like we see it's a great option as the crotch is U shaped and there's no included bark I can see.

Slowly the union will change to a collar as one leader assumes the trunk role the other a branch. Subordination also makes for smaller dia cuts that seal quickly.

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jmcg.insight.gardens

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Any links on that Eric? Sounds interesting.

Julie

Eric Frei

It's pretty common knowledge but I have loaded up a section which includes it.

http://www.treeworld.info/f42/strate...ees-15152.html

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jmcg.insight.gardens

knew the method not the terminology, now I do.