Codominant Stems

[Acer]

I'll soon be working on a silver birch, around 15 yrs old, 40' approx. At about 25-30' , the single stem divides; I'd imagine the two stems were codominant for a while. One stem is roughly in line with the axis of the main stem, but the other larger stem pushes out, making the crown lopsided. I think some subordinate pruning is in order, and I'd like to reduce the larger stem to a point below the smaller stem. However, would this upset the growth control system of the tree, given that I'll be reducing the dominant stem? Removing an entire stem at the point where they divide would give a wound with diameter equal to what remains, so I want to avoid that.

here's hoping the (poor) diagram arrives and explains the situation..

Thanks for any responses

 

[treeclimber165]

Something like this is how I might do it. I'd stress to the customer the need for me to follow up in a year or so to reduce it further.

 

[Kneejerk Bombas]

My first concern would be why the smaller half is stunted. If there is a physiological reason it's smaller, such as borers. You know, just so your subordinating the correct side.

I simply used the eraser on your picture to show the cuts I might make. Several small cuts are better than one large cut, and doing the subordinating in stages over a number of years is also better, IMO.

 

[M.D. Vaden]

BIRCH CO-DOMINANCE

Hi,

Sure like Mike Maas idea.

Exactly what came to mind.

It may possibly produce multi-dominance, but who cares as long as the tree is healthy.

Your diagram makes the union appear to be a strong "U" shape.

Mario Vaden
Landscape Designer / Arborist
M.D. Vaden Trees & Landscapes
Beaverton, Oregon

 

[Stumper]

There are situations where I might use 165's method but I think tha Mike's solution is better on this drawing. If access is possible to make the proper cuts and the laterals exist where I've drawn them in then I might go for this 'gentle' treatment.

P.S. maybe I should have said "tried to draw them in". The new lines are pretty fuzzy!

 

[Acer]

Thanks for the advice.

Mike, I don't suspect health problems, it's just that the larger lopsided stem has beaten the other to the light. The larger one is on the south side of the tree, which may explain.

Mario, the union does look strong, with a nice U shape rather than a V shape.

I'm pleased that noone thinks I'll be doing the wrong thing. The reason I posted the question was that I once did some formative pruning on a Norway maple standard (5 yrs old or so). One shoot, starting from half way up the tree, had gone out then turned parallel to the stem and raced ahead of the rest of the crown. I removed this at its point of origin. It didn't seem that drastic a move, but it must have upset the tree, as it produced a fair amount of epicormic growth, especially around the wound.

The same job involves reshaping an Acer platanoides 'crimson king'. Here, I'm planning to reduce a few branches on the south side, to balance a lopsided crown. The tree has probably been shaded on one side by a Robinia, but we are removing this one altogether, as the root plate has been lifted by the recent storm. Luckily, I don't need to touch the top, so I don't expect to see too much growth disruption if I take it easy. A light reduction this year, and maybe some follow up next year, depending on how the tree is doing taking over the space now occupied by the robinia. We'll be pulling out any crossing branches at the same time, whilst removing no more than 10% of the foliage - less if possible.

I'm really excited about doing this work because, for once, its a chance to do some formative pruning work which, in balance, should extend the life of the trees. These are all around 15 years old, have plenty of room to develop, and more importantly have a fairly clued up owner who's looking years ahead and is not whingeing about them being too high and dropping too many leaves. Most trees in this particular area are hacked at about the 15 foot mark. The neighbour has three giant hat racks which were silver birch trees. This is the sort of work I started out to do, but probably takes up 10% of my time..

 

[treeclimber165]

It really is nice when the customer understands enough about trees to look ahead. It's easier when a neighbor provides a visual aid of what 'hat racking' will look like in 10 years. I love it when I can talk a customer out of doing that and letting me train the growth into a healthier structure instead.

You guys were absolutely right about smaller cuts. I guess I didn't finish my thought on my earlier post. About 1/3 total reduction is what I was going for, with a good part of that coming off the top of the stem. Other cuts as necessary to reduce longer tips and stunt growth of the lead.

 

[murphy4trees]

I would go with Brian's recommended cut... probably...
although either would do.. the one cut is easier and just as effective IMO.. Although if there were health/vigor or Aesthetic concerns I would consider going with MMs sugestion..
Does that make me a limb chopper????
God Bless,
Daniel

 

[John Paul Sanborn]

Dan, axiom of the trade "keep the cuts small". Reason; Deacy, CODIT "wall one" is the weakest and birch is a poor comparmentalizer.

I would do something along the lines of what Maas described. you need to subordinate the entire portion of the canopy to effectively reduce vitality. I might even bud prune the other side to induce more hight in the terminal.

 

[Kneejerk Bombas]

Murphy4trees writes:

"Although if there were health/vigor or Aesthetic concerns I would consider going with MMs sugestion..."

Hehe, most of us don't care about those minor things, health, vigor, and appearance...


I would like to emphasize that codominance training can not be done with one small set of cuts. If you did the pruning I showed and then came back to the tree in 3 or 4 years it would be even bigger compared to the other side. It will take repeated trimming to subordinate the limb permenently.

 

[murphy4trees]

Clientelle

Both are Good points..
And if you work for the kind of people that have their trees looked at/worked on every 6 months.. then OK.. better for the tree and that gives you something to come back for and puts a few more $s in your pocket.
I worked with a climber this weekend that says his regular employer works only for the super rich.. he'll often prune the same trees every 6 months or sometimes even every 3 months..
We were talking about cabling a large maple and he asked if if he should get the deadwood.. I replied "that's a given... goes without saying"... Not at his regular job... they leave the deadwood when cabling for another reason to come back in 6 months....
My clients don't go for that... they call me to solve problems... not to do regular maintenance on their trees....
So when subordinating a co-dominant stem I'll usually do it in 1-3 cuts... I may not see that treee again for years if ever.. I make the best cut I can and hope the best for CODIT... That's rarely a safety issue as large co-dominants will usually get cabled.
God Bless All,
Daniel

 

[John Paul Sanborn]

.5 year cycle is way too much except for small ornimentals.

You can effect vitality in co-dom's if you are on a 2-3 year cycle.

You can get theat by setting the customer's expectations in the sale and then running a file to follow up on the client. Say 2 years later you stop by and take a look, then leave a not stateing thet pruning is needed this year or next.

I'm not saying that it can be done every time, but the proper approach will increase the number of clients you have, vise the one shot customer who shops around.