AusBonsai

I have 2 chinese elms that have started to lose bark around the soil line up i re potted them both and trunk chopped a month ago . can anyone tell me what i did wrong , is this root rot?

Any chance you could post a couple of photos?

I think it is too wet. Not 100%

What did the roots look like a month ago?
White, brown?
Was the soil always wet and smelly?
Normal?

Looks like the soil could be a bit too wet to me. Sometimes that rot will stop but sometimes it continues around the tree and kills it in my experience. I hope I am wrong but your first one could be a goner.
Others might have more knowledge on this but if they were mine I would repot the second and cut away the rotton part. Might make a nice hollow trunk perhaps.

Regardless of what it is, you have to treat it. Paint the affected areas with undiluted lime sulphur, being careful that it doesn't drip onto the soil. Let dry. Take trees under shelter and stop overhead watering for a few days. By the looks of the soil and the wet collar at the base of the tree it is indeed too wet, so no watering should be OK.
I may be wrong, but it doesn't look as if the cambium has been affected yet, so your trees may be all right.
From experience, Chinese elms are sensitive to bark necrosis, i.e. a fungus that eats away the cambium under the top layer of the bark. Then you can just peel off the bark in strips. The fungus can enter via cuts, so I have found it best to seal any major cuts. While it doesn't look as if your trees have that fungus, it may still be wise to clean the trunk chop cuts with diluted lime sulphur, ratio 1:10, and seal them.
Finally, are you plagued by snails and slugs? You may think this crazy, but big snails and slugs will eat the bark that has been softened by too much water! Friends and I once bought at a big discount some nice Chinese elms that had been ringbarked at the bottom of their trunks, and the nurseryman told us that he had caught the b....s damaging the trees, and they were big snails! I am happy to say that all our trees recovered. So in your place I'd put down some snail pellets round your trees.
Good Luck!

Lisa

mick the roots were ok a month ago there was a small amount of root rot on one of them which i removed . roots were brown . didn't notice any bad smell.

lisa thank you . i will lime sulphur today should i water the lime suphur in as well ? or should i lift them out of there pots again and check the roots ?

oh yea there are a lot of slugs in my yard and i noticed a big snail just yesterday , hope that is the problem . know slugs and snails love beer so i will be setting a some traps by setting a few jam jars of beer around the yard .

Hi Paul,

No, don't water the lime sulphur in, as it could kill your tree, especially when it's undiluted. Paint the affected areas with a soft brush (acrylic, not natural hair) that has just enough lime sulphur on it so it doesn't drip. Then let it dry for a couple of days, it won't come off once it's dried properly. Again: no overhead watering while the stuff dries!
Treating your snails to a drink of beer might make them pass the word around, so that you catch a lot of them, but who is to say they mightn't prefer a nice bite of elm bark first? Seriously, I think you need the snail pellets.
And generally watch the watering of your trees. Can be difficult when you have prolonged periods of rain, in which case you need to put wicks in the drainage holes of the pots, to drain the water away more quickly. Or else you need to re-think your soil mix, using a less water-retentive combination. Well, I guess you know all that. Sorry if I got boring.

Lisa

Years ago I had the same problem with a Chinese elm I had. It seems like your base is constantly getting very wet and not drying up thoroughly.

Try to water the surface only, and keep away from those areas as much as possible. Also, once those areas dry up scrape the wet and presumably rotting bark off the regenerate some new ones. Hopefully that will work...best of luck with them though, hate seeing trees dying...

BTW, when I did that my Chinese elm tree survived, but I was interested in other projects so I gave most of my other bonsai away to friends..
Caught the Bonsai bug again, and now it is staying till my retirement which is 31 years away and counting................................

Cheers,

Han aka fatming