Root stock vs. Scion

Discussion in 'Maples' started by Atapi, Jan 13, 2019.

  1. Atapi

    Atapi Active Member

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    Hi, I have a general question related to the root stock and scion of a Japanese Maple.
    Is the growth of the JM depends mainly on the root stock or from the scion?. For ex: I bought two Acer Palmatum 'Bihou' about the same time, both are 2nd yr grafted from the two different places in Oregon about 3-4 yrs ago. One of them now is about 5-6ft tall while the other slowly grows about 2 ft tall.
    So I was wondered is the strong root stock will help the tree grow faster or it is depended on scion? or any other factors that you can share with me.
    Thanks.
     
  2. JT1

    JT1 Contributor

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    Good question! It can be both. Poor root stock can effect growth and the overall strength and longevity of an individual tree.

    Scion selection is extremely important too, but even before that you need a good "stock plant" or the cultivar being grown for the purpose of harvesting Scion wood. Scion wood in a perfect world would be from the true cultivar that is healthy and not over fertilized, free of bacterial infection. Also it would be taken during SUMMER! Summer time is the only time a grafter can make sure the Scion wood is true to form in growth habit and healthiness.

    Root stock is also very important. Red leaf Acer palmatum tends to be slower and is more prone to split during winter. Tends to be weaker over all in our climate. Some varieties of red leaf root stock can be unstable and cause the cultivar to revert or become unstable.

    The root development is another factor to the quality of the root stock that effects the growth and health of scion. Girdling roots can starve the tree of much needed water and nutrients. Poor root structure and development is another factor.

    The bacterial count of the scion or root stock can also be a negative factor. The tree may not show any black bark but it doesn't mean that bacteria is not present. Some trees can have very high levels of bacteria in the vascular system which limits strength and longevity of the tree. Some infections can clog only part of the vascular system that limits the trees growth rate.

    I have several post on the impact of fertilizer on growth and development as this could be a factor. Aside from everything mentioned micro climate between the two trees could be a factor. When Japanese maples are placed somewhere that is too hot, dry, windy, or roots staying too saturated can cause a tree to leaf out and then grow very little if at all.
     
    AlainK and emery like this.
  3. Atapi

    Atapi Active Member

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    Hi John, as always thank you for your insightful input.
    I believe what I can do now is caring for their root growth, development, fertilizer... since we are not the one chosen the rootstock and the scion in the first place. We all want to see each of them grow well but sometimes I feel that I need to take a lost by get rid of the one that didn't grow or make any progress instead of hanging with it w/o seeing the beauty and satisfactory from the tree(s).
    I do take your input as well as other frequent contributors seriously and begin to watch each of my tree a bit closer on their growth progress and building my own trees character list.
    Thanks again, steven
     
  4. emery

    emery Rising Contributor Maple Society 10 Years

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    This is a very good question, and one that doesn't get asked enough. John has given great information as usual, here are my 0.02ยข.

    Root stock is obtained from seed, usually from a plain green or red Acer palmatum that germinates well. Traditionally propagators have used red only to graft red-leaved selections. There has been some scientific work on DNA migration across grafts for red-grafted-on-green, which may explain this choice.

    If I start with 100 seedlings from my green palmatum and grow them out, I'll end up with some different maples in the lot. Some will be slower growing, some faster, some will have bigger root systems, larger or smaller leaves etc. There may even be some dwarfs, variegates or dissected maples in there.

    In the rest of the horticultural world the concepts of "dwarfing rootstock" is well understood, and of course it's the same for maples.

    Naturally some of the stock plants just won't be that healthy, but it doesn't matter, because the interest is to grow them rapidly and get them out the door. What's more, fertilizer makes nice straight understock. So they're very prone to bacterial disease, either externally or from the scion itself. (How many young grafts turn black just under the graft?)

    After you order them, they will usually arrive bare rooted. In order to provide the best stock they should be potted into small pots and left for 12 months to establish the root system. But, that is expensive, so it may not happen with all propagators. If it doesn't, the relative size of the roots of the seedling can make a huge difference in early graft vigor.

    And on and on. You can see, there's a big variation in the stock, and it causes a big variation in the results. I have identical grafts -- same stock plant -- I've done on larger/smaller gauge stock, they yield different sized results...

    -E
     
  5. Atapi

    Atapi Active Member

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    Hi Emery, wonderful input. Thanks.
    I am living in the East of US but most of mine were ordered from the West i.e. Oregon, Washington... and I sometimes observed what grows well there doesn't guaranty to do the same in my area and vice versa.
    I am also able to search thru our JM forum and found this same topic has been brought and shared by many experienced growers like you.
    Thanks again, steven
     

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