Quercus Robur - Wound treatment

Dear All,

I watched the ‘Zelkova Fall Clean-up’ session and wanted to apply the technique to treat a large wound on my Quercus Robur.

It appeared that the wood was more hollow then I expected - the surface layer was rotten and when removing, the wound became quite big.

I removed the bark at the sides around the wound with the idea to open it up until the cambium layer in order to stimulate the growth of the callus (to close the wound over time). However the layer under the bark doesn’t look light green (as cambium does) but white. I think that this means that the wood underneath is death (see picture).

How should I treat this wound ? As this is the main branch/trunk of the tree, I’m afraid that it will die off with time (as the wound gets more hollow due to rain)

  • close the wound with some kind of ‘cement’
  • use a wood hardener

This concerns a very nice tree - I would hate to loose it

Thanks for your advice!

You could hunt the live vane with a blade, then remove dead bark and apply cut past to the cambium.
Looks like the wound was big and started to callus, then the callus has died back?
Does the tree have other health issues?
I think you will struggle to heal this unless you stick it in the ground and let it grow rampantly.

Hereby a picture of the complete tree


That s an awsome feature. Goes well with the base.
PROBABLY will never heal compleatly.
(Imho) I would treat it with a light sulfide swab for rot, let it dry, and cutpaste.
WATCH for the new rollover of calus next summer, and gently cut to encourage it as needed. Knife and chisel. I do use a fine burr on a dremmel on dead edges to help calus fill in on large trees. GENTLY…
Are you in a warm winter area? My robur lost leaves 6 weeks ago…

Hi @Pellskin,
How are the calluses rolling on the base? The reason I ask about the health is if it is struggling to produce vascular tissues, it could be a sign of another problem? (Nice tree)

Hello Andy, Kurt,

Thanks for your feedback and advise.
Overall, the tree is doing quite well. It is indeed true that the tree has another wound (cut) a bit higher up on the branch/trunk. This second cut/wound is on the other side of the trunk (not just above) but it could have caused the callus to have died back.

I’m sad that I did this (fiddled with the wound) - I should never have touched the wound and it should have been kept it as ‘natural’ as possible’ ; I hope that, after some time, my mistake will not be noticeable anymore.

I will probably treat the wound with a “wood preserver” for deciduous trees (see www.kaizenbonsai.com https://www.kaizenbonsai.com/natural-bonsai-deadwood-preserver)

I live in Europe (Belgium) - the winters are not so cold ; currently the temperature is still around 12-14 Celsius (so quite warm for the time of the year). The leaves are starting to change colour (the pictures with the green leaves that I’ve posted are taken in the summer).

Thanks again for the feedback!!
See attached for some more pictures.

Best regards,


Other picture


Other picture


I know what you mean about feeling sad for removing the dead bark. I poked around on an alder and exposed a dead section which ran in a straight line, and looked awful.
However, in the long run it will add to the appearance of age. To show a live callous rolling over a dead callous tells a more interesting story than just a healed over wound. Bonsai is all about depicting triumph over adversity.

I personally think the wound looks pretty nice at the tree and I would like to see it like a feature. Think about to further hollow the trunk at the two wounds and try to make the edges more wild to mimic the hollows at the base.

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Thanks you all voor the advise!

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Personally love oaks. If my tree would just let it heal and age naturally rather than preventing the wood rot. It will appear much more natural in a few years:wink: