Codominant trunks

Discussion in 'Maples' started by debviolet, Apr 9, 2018.

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  1. debviolet

    debviolet Active Member 10 Years

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    Hi All!
    How do folks feel about codominant trunks in Japanese maples?
    I usually remove one codominant trunk: many times mail order trees have them-they seem to allowed to develop by many nurseries devoted exclusively to Jpn maples.
    My local nursery has one
    Tsukushi gata , about 5 feet tall with two narrow angled codominant trunks, each maybe an inch in diameter, at least.
    I've long wanted this tree, or an umegae, and at 62 years old, it would be nice to get a bigger tree.....but I want a healthy one...if/when this tree's trunks grow so close they develop that bark that seems to join them, will this be a problem in a tree that tops out, I believe, around 12 feet?
    Thanks in advance!
    Debviolet
     
  2. 0soyoung

    0soyoung Rising Contributor

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    Often they are pretty, but they are mechanically weak and prone to splitting, which is likely why you are removing them. I have had a tsukushigata for a number of years. It has never had a codominant trunk or similar issue - it didn't have any such issues when I acquired it nor has it developed any.

    I've noted that pruning time influences the branching angles. Pruning in August tends to release new shoots with a very narrow angle - the kind of codominant trunks. The first shoots in spring seem to have the widest angle. In other words, one maybe should restrict structural pruning to shortly after leaf drop and/or as buds swell in spring. On the other hand, I've also read that cytokinin levels influence branching angles. Low cytokinin levels correspond to low branching angles. Cytokinin levels tend to reflect nitrogen availability, so supplemental nitrogen may also help to increase branching angles or, equivalently, eliminate codominant trunks/branches. I wonder if the grower(s) maybe has a routine of spring grafting and late season pruning that would correspond to these observations of mine. Possibly.

    At any rate narrow angle branching is prone to splitting, so codominant trunks are not desirable on a landscape scale. In bonsai, can be interesting, IMHO.
     
  3. debviolet

    debviolet Active Member 10 Years

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    Hi Osoyoung!
    Yes, the splitting issue is why I have been removing them, but I was hoping maybe I had been exceedingly prudent, and folks would tell me it wasn't necessary. ..

    Since I do not want to shock trees by taking off large percentages of them, I spend a few years cutting back the one codominant bit by bit, and then must wait as the trees rebalance with new side branches in the newly opened space....or, I buy really young trees that I prune to my pleasure, but must wait to achieve any size on them.

    I get both more and less patient as I get older:-)

    Thanks for the info on pruning times, nitro, etc. I did not realize that branching angles may vary seasonally, and I will now be looking out for that.
    Cheers! Debbie
     
  4. Iowa Jim

    Iowa Jim New Member

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    I have a jordan that had the same problem and was concerned about a heavy wet snow. What i did was first year let it alone to get established because it was only a 5ft. tree. Second year around June 1st. i cut half of it off. Third year around June 1st. cut down to the branch collar. Where I'm at in zone 5a its just to big of a risk not to. Glad i did because we have had some very heavy wet snow this year , along with 3 straight nights of -25 below zero air temps. I'm a little worried about winter damage this year. : good luck with what ever you decide:
     

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