I air layered the top off this elm (English?) a few years ago. This summer I noticed a dark gel growing on the dead side of the tree. The tree is healthy, and I have not been too concerned about the gel, as I want the stump to decay a bit to look like an old coppiced tree.
Dose anyone know what this is?
My plan is to repot in the spring and remove the gel unless anyone has any other ideas?
Bacterial wetwood
https://www.extension.iastate.edu/news/2007/jun/070801.htm
On another note, in the last pic, the moss in the bottom right corner is very invasive. I would remove it, it can cover the hole top of your substrate in a season. If left unattended it is a real chore to get them out, I speak from experience. The top 1”(2.5cm) come off in a root filled mat.
Off topic, but I thought I would let you know 
2 Likes
Thanks @MtBakerBonsai
Exactly right. I know what you mean about the moss week, it’s savage.
1 Like
Are you in the UK Andy? I had the same on my trees due to the recent sustained wet weather although nowhere near as bad as yours.
I scraped it all off.
I also have that same moss (bottom right) on my trees. I pluck them out as they appear
Hi @Amitdesai1978
Yes, I’m in SW UK. Maybe it was the summer we have just had. Tree has been growing well and no sign of wetwood on the air layered top.
Hi @AndyK,
I would check it thoroughly as a lot of cankers ooze like that. Unfortunately if it is there’s only one thing you can do. Hope it isn’t. It has, as continues to be a very wet year in UK which exacerbates the problem. You can try cleaning off all the dead wood and sealing the wound with cut paste. Then it’s a waiting game until next spring to see if it’s within the tree itself.
Thanks @Keith-in-UK
The stump is quite large in comparison with the trunk coming of it, so it’s no surprise that a section of it is in collapse. I will post in the spring to show the repot.
Hi @AndyK, the more I look at the pictures the more I’m convinced it’s a bacterial canker of some sort. I don’t want to put a downer on such a nice tree but in my opinion it may be worth ditching it to protect your other trees. I had something similar and simply wiped off the gel, not knowing what it was, and carried on trimming and pruning it and my other trees. I had eight infected ones before I looked round. Once I found out what it was I threw away all infected trees (some I’d had for twenty years or more!), sterilised all my tools and scrubbed every surface the trees had come into contact with. I also quarantined other trees that had been in close proximity for 12 months out of precaution. The canker can live on the leaves and you may notice little shot holes in them. It can also be spread by insects. If you can’t face throwing it away, at least keep it at a fair distance from your other trees if you can. Sorry for being pessimistic…
Thanks @Keith-in-UK
I will hide it away. The air layered top is much better. Would be a shame if I lost it.
1 Like