How to get rid of Pseudonomas starting to appear on maple tree branch

Discussion in 'Maples' started by ChrisUk, Feb 20, 2022.

  1. ChrisUk

    ChrisUk Active Member

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    Hi,

    I've noticed some pseudonomas (I believe) growing on a main branch of our Sango Kaku since late Autumn I think.

    That branch is about 2cm of diameter (less than 1 inch). where the black is. The branch still goes quite high from where the black area is (about 1m higher I would say), it's one of the three main branches of the tree (the tree is about 2m high (6ft)), so I would like not to have to cut it, if possible

    I tried to put twice some Vitax Copper Mixture on it but I am not sure that it has done much. Apprently it's offen used as an alternative to Bordeaux Mix. When mixed with water ratio shown on the bottle, it's quite watery so I think it doesn't stick that long.

    Maybe that's much weaker than bordeaux mix (with lime), or copper sulfate only (i.e. in water, no lime)?

    What would you think I should do? Spray some every few days (since it's quite wet at the moment, each application wouldn't stay long)? or trying to scrape the area (this would be risky and expose quite a bit of wood)?

    Thank you

    IMG_6200.jpg
     
  2. emery

    emery Renowned Contributor Maple Society 10 Years

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    Hi Chris,

    I think the spots are much to small to justify any kind of surgery -- you say "scraping", but really you would cut around into the clean wood -- and can be cured with copper. Indeed, you see the white/gray spots on the interior of the black; that's where the infection is dying. However, the active edges of the infection are still spreading.

    I don't know the product you reference, but the one reason the lime is included in Bordeaux Mix is that it helps the product stick to the surfaces during wet.

    You could try either a different product, a higher concentration or spray more often, e.g. after rain, re-apply. Some will suggest a copper paste, my personal opinion is that paste penetrates less well than frequent spraying. If this has been, as you suggest, persisting for a long time, I'd up the concentration and spray every 3-4 days.

    For what it's worth, I think this maple is going to be just find, it will end up looking like just another bit of gall once it heals.

    HTH! -E
     
  3. maf

    maf Generous Contributor Maple Society 10 Years

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    Very good advice above from Emery. I don't myself use any chemicals on my maples, even something as innocuous as copper, but appreciate that others have a use for it. Either way the small size of the black lesions suggests the tree is, at least for the moment, well on top of its own defence and not yet in need of any extra help. I agree with this:
    People in the JM community have suggested that pseudomonas bacteria generally invade from the branch tips downwards, as is often seen starting in small blackened twigs and progressing down, and that black spots lower down on the bark are caused by a different infection. I am in no position to verify if this is true, but common sense suggests that anywhere there is an opening in the bark that these bacteria can enter is a potential infection site. I think it may be that mature seasoned wood/bark is better able to deal with the infection at source and stop it from spreading too much, whereas not hardened properly twigs are just kindling that fuels the infection. Also, our relatively mild weather this year would help as pseudomonas are ice nucleating bacteria and, as such, their potential to do damage is greatly reduced if the temperatures are not below freezing.
     
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  4. ChrisUk

    ChrisUk Active Member

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    Thank you @emery and @maf for your sound advice!

    I will check in the next week (or two) if it progresses (I forgot to take regular photos since it started to check the progress), and see whether I'll spray a bit more.
    The bark of my sengo kakus and bihoos have way more small lesions than the other maple trees. So I was always wondering whether they'd be more susceptible to get infections. One of the Bihoo seems to often have bacterial infections around those lesions.
     
  5. emery

    emery Renowned Contributor Maple Society 10 Years

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    You're welcome! Indeed, all of the coral bark group is very susceptible to pseudomonas (or other) infections, none more than 'Bi hoo'.

    I've noticed, a regular JM gets rather red bark when there is difficulty moving sap in the area. This can be because of sun, wind, etc. This red bark is then very vulnerable. I wonder if the coral barks have thin bark without much protection for the cambium, and little sap flow, and that's why they're so prone...
     
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  6. SimplyJMaples

    SimplyJMaples New Member

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    I just pulled one of my 'Sango kaku' trees out of the ground. Two years it was there. After the first year, I had to cut several branches off because of pseudomonas syringae. Then last summer, the tree rebounded nicely with nearly three feet of new growth. Not exaggerating at all. Then, as the winter wore on, and we approached spring, the disease took over the tree. This time, the infection had spread to the main trunk and down to the graft point.
    This was the variety that really made me fall in love with Japanese maples. But it's been frustrating to see this situation happen. I haven't given up on the variety however, I won't put another one in the ground again until it is many years old.
     
  7. emery

    emery Renowned Contributor Maple Society 10 Years

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    Hi, Sorry you lost your tree. Maples can certainly be frustrating!

    That's really a lot of growth, and very hard to get that much hardened off, which of course makes it all the more susceptible to pseudomonas. This is why we generally recommend none, or very light fertilizer, though sometimes cutting back hard alone can result in long whippy growth.
     
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  8. SimplyJMaples

    SimplyJMaples New Member

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    In my case, if any fertilizer was applied, it was a very low N (5%) fish fertilizer. I don't believe I fertilized it in summer. I sterilize my pruners.
    And, although I planted the tree mounded up above the surrounding soil, it sank and I believe that also may have contributed to the disease. Fairly wet, coastal locations with a wetter than normal fall and typical, wet winter.
     
  9. emery

    emery Renowned Contributor Maple Society 10 Years

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    I've had that happen with mound planting too. I agree as soon as the area above the root flare is covered, it can lead to these problems.

    It sounds as though the growth was caused by the hard cut back, but it's funny how maples can come up with a lot of growth out of nowhere. We were just looking at an A. pectinatum 'Sparkling' in the garden, planted in 2008. It sat like a lump for 13 years, with maybe 3 cm of growth per year; Lots of bark problems. I had pretty much despaired of it growing into a healthy shrub; but last year we had a very cold, rainy summer with very little sunshine -- something most maples didn't like at all -- and it sent out huge meter long red shoots, with lots of side growth and very long inter-nodes. Just as if I'd massively fertilized, though I haven't touched it for years. Not too much die-back on it either! But the growth is very awkward and whippy.

    In short, sometimes it's a straight "go figure".
     
  10. AlainK

    AlainK Renowned Contributor Forums Moderator Maple Society 10 Years

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    I think that in Powell river,BC, you get snow in the winter, right ?

    This kind of bacteria is naturally present in the snow. Some bonsai enthusiasts who live in countries where there's snow in the winter apply sulfur (diluted lime sulfur) or copper (Bordeaux mix), or a combination of both, first after leaf-fall, then before budbreak.

    The mechanism of how Pseudomonas makes a protein called INP to transform water into snow is mentioned in this article (in French) :

    La neige et la bactérie P. syringae

    Here, a couple of days with snow is a memory of the past, but where you live, I would say it's essential to prevent your trees from such diseases in Autumn, then in late winter/eraly spring...
     

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