Appropriate Japanese maple cultivars for Zone 5a.

Discussion in 'Maples' started by directorrod, Jun 14, 2018.

  1. directorrod

    directorrod Active Member

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    Location:
    Rockton, Illinois, USA. Zone 5
    My friend and fellow Japanese maple enthusiast Elisabeth Witt has been encouraging me to post information about growing them in Zone 5. The following is based on my own experience and is not purported to be scientific fact. My opinion is that the zone information on some cultivars is not entirely accurate. I have a collection of 540 different cultivars and well over 600 trees, most of them thriving, but after years of replacing certain cultivars after winter dieback I’ve come to the conclusion that there are simply some cultivars sold as appropriate for Zone 5 that are not really sufficiently hardy to be labeled as such. Let me begin by saying that in my location on the border of Northern Illinois and Southern Wisconsin winters can be particularly brutal, so what I say may not be the case for everyone, but if you are located in Zone 5a and your winters are harsh, you may want to avoid cultivars with which I’ve personally experienced repeated failure. Sango kaku, Orange Dream, and Mikawa yatsubusa annually have a complete branch die all the way back to the trunk (that survives to send out new branches the following year.) Other very popular cultivars that lack winter hardiness in extreme conditions are Shin Deshojo, Shishigashira, and Kamagata. Almost all the colored bark cultivars are susceptible to significant winter dieback. I was very sad to lose the beautiful Radiant TM that had been provided me by David Freed who introduced it and asked me to test it. A few cultivars that I believe may be more recent introductions that have failed to thrive are: Kawahara Rose, Giganteum, Tendoh, Koyasan, Kawahara midori (numerous attempts,) Shirofu nikishi, Koshibori nikishi, and Murehibari. Let me be clear that I am not suggesting dishonesty on anyone’s part. Nurseries are going on the information provided them. I think the people who actually assign the Zone ratings simply don’t know how cultivars will respond to the extremes within any particular zone. I suspect this is true to some extent for the warmer zones as well as the cold.
     
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  2. Iowa Jim

    Iowa Jim New Member

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    Location:
    Waterloo,Iowa
    Thanks for the tips. I also lost some trees this last winter that i thought i would never lose.Read my last post and it will explain,also in zone 5a in Waterloo Iowa. Old man winter was pretty rough on us.
     
  3. directorrod

    directorrod Active Member

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    Location:
    Rockton, Illinois, USA. Zone 5
    I read your last post, Jim, plus all your other posts and replies to them. They were all useful and relevant. Thank you and your respondents for the postings.
     
  4. emery

    emery Rising Contributor Maple Society 10 Years

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    Nice one Rod. Let me ask you this: in your "borderline" zone, do you ever see understock failure? That is, it's not the top that dies, but rather the black freeze marks are around the graft union, sometimes going from the understock into the cultivar. Or the black rings the understock below the graft union.

    My experience is that some stock providers are using Sango kaku (or similar green) seed, because it's very easy to germinate and grows quickly; but it may then be less hardy than the wood it carries. I lost a large Eddisbury from Spain this way in the brutal 09/10 winter. The understock died completely, and the top was fine, but of course died shortly thereafter!

    -E
     
  5. directorrod

    directorrod Active Member

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    Great question! I'd say 0% understock failure in my experience.
     
  6. ROEBUK

    ROEBUK Well-Known Member Maple Society

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    Location:
    West Yorkshire, England
    Some pics of my Koto no ito which is going through what emery suggests , never seen this happen before to any of my maples but here we are !!

    One side of the tree is gone pic 1 & 4 and you can see where i have removed the dead wood from the dying branch , but i am just leaving that branch for the present time because as you can see on pic 5 there are four new back buds growing which i find very strange to say the least, top left bottom right and two central new growths now it remains to be seen if these will grow any further but i wouldn't have thought so seeing that the understock graft that is suppoting the actual cultivar is dying ?

    The other side of the tree seems to be fine at present does have leaf straps but ......

    Any light anyone?
     

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  7. 0soyoung

    0soyoung Member

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    Location:
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    I would be layering (marcotting) it off the root stock. It is effectively in that state now but for lack of a damp medium around the union. Cut a girdle and any roots that get generated would be on a plane instead of the irregular contour of the union.
     
  8. ROEBUK

    ROEBUK Well-Known Member Maple Society

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    Thanks for that info have just been watching a few videos on YT on this technique seems straight forward enough and i understand what you have stated so i know where to start on the bark so i think i will have a go at this next week and see what we can do to try and get new life again, plus it will be a method that i have wanted to have a try at to see what results i will get if any ? nothing to lose with the tree in it's present state.
     
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  9. JT1

    JT1 Rising Contributor

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    I have seen this happen. Underneath the light brown colored bark is live tissue. Although it appears as that dead tissue surrounds the trunk, there is live tissue allowing passage through part of the vascular system, enough to keep part of the tree alive.

    Actually I have seen this in koto no ito, so this variety is better at overcoming these challenges than other varieties.

    How it happened. Our Koto no ito was hit by record cold and the duration of cold was record breaking too. I don't think this is the case with your tree. In the case of your tree, it appears it has a history of bacterial outbreak and recovery. While one outbreak occurred, let's say early spring, the outbreak was not widespread. As the season progressed the outbreak went dormant. The tree started to form wound wood underneath the dead tissue and this wound wood is more resistant to future outbreaks. So next spring another outbreak occurred in let's call it virgin bark (meaning bark free of bacterial outbreak). It tends to form outside of the brown area from last year. The outbreak spreads in early spring, but as optimum conditions change the outbreak goes dormant. Again it clogs that area of the vascular system and some more branches in the canopy are lost. The more this happens the more you get wide spread spots down stream through the upper trunk and failure of branches as overall health declines from repeated asults. As the tree leafs out again and gains strength it starts to form wound wood underneath the dead tissue, ECT. The cycle continues each season, maybe a season here and there are more or less severe and the tree gets more branches back after an easy spring or may loose more on those harsher wet Springs. Kind of a battle that goes back and forth more or less over each season. But eventually you get a tree that looks like yours where someone looks at it and says how is this thing living! It's the healed tissue of past seasons that are keeping it alive.

    Why is this happening? Some trees have higher number of bacterium at time of grafting that explodes whenever stress conditions are right. Some get it from contaminated soil, and others get it from cuts caused by cold, frost, that is introduced from the environment or unclean pruning practice. Using synthetic fertilizer also promotes bacterial outbreak and weakens the tree by using up sugars, killing beneficial microbes in the soil, and makes the tree more prone to cold damage.

    We don't know for sure the history of your tree from grafting to present day, but we do know that it has a history of bacterial outbreaks. We can't control the past but can control the present and future to limit future outbreaks.

    The first problem is the original soil. I can see that the soil closest to the trunk in one photo is too wet, spongy, and is a contribution to the challenge this tree faces in early spring when conditions are prime for outbreak. We have a grower east of here that used to grow really awesome unusual plants. They hit the hardship of 2008 and brought in a CEO who said they could solve all their problems by using a one size fits all soil. They grow a wide array of plants from succulents to willows and everything in between. This soil sounded too good to be true. The first growing season with the soil went really good. BUT then Winter came and our winters can be very cold and extremely wet by frequent thaws, warm, rain, then back to extreme freeze. This cycle is very tough for Japanese maples. Since the soil holds so much water (note it is free draining, but still absorbs and holds a lot of water) the tree trunks cracked at the base on some varieties, but all had serious bacterial outbreaks. Once the growing season starts the trees would grow well in the soil and some over time would catch up, fill in the areas of loss. But every winter and early spring brought more damage. Over several seasons they only had bushy varieties of Japanese maples to sell, because the foliage hid all the damage to the bark. Many varieties that tend to be more open or weaker growers were lost or sent to the burn pile. Now this nursery mainly grows boxwood and is a shell of what it used to be because one soil does not fit all!

    My Koto no ito was given to a friend, planted in some morning sun, afternoon shade, that has great drainage. The tree is still going. We had to replace it because it was no longer garden tour worthy. We replaced it with one that looks great and has no problems.

    My advice is to get as much of that soil out of the roots as you can with a hose stream of water and pot it in a good mix that is not so spongy or put it in the ground free of the spongy soil. Avoid synthetic fertilizer and weed killer like round up as both will continue to weaken the imune system of your tree.

    A safer approach is to vertical mulch to help combat the sponginess and allow the tree to gain strength over the growing season, then re-pot in fall to clean out the spongy soil before it becomes a problem again in late winter and early spring. Tree does not like that much moisture in roots while dormant and the tree has hard time fighting off bacterial outbreaks when dormant. Fixing the soil is a must, but to do it now on a weak tree is a cause for total failure as any set back is a chance for the bacteria to win. Vertical mulch gives it a fighting chance. We can repot anytime with proper precaution and skills, but the tree has to be healthy to play along. Given the history, vertical mulch now and re-pot or plant once the growing season is over but before winter as it may not make it through another cold wet dormant season.
     
    Last edited: Jun 17, 2018

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