Hello, I have a fairly young Chinese Elm (about 9-10 years old) and I have noticed what looks like fungus growing up the main trunk of the tree. I don't know enough to identify it but the closest I can find from google is coral spot fungus but I don’t think that’s right. Most websites about fungus on bonsai seem to be about fungus that targets the leaves so I haven’t been able to find anything bonsai specific.

The leaves on my own tree seem to be a healthy green although some of the longer, more distal branches don't have leaves but these haven’t fully re-leaved since repotting before winter (when I did my first fertilising in Spring it looked like the leaves were all returning but this stopped which I just assumed was because the roots won’t have recovered enough yet to support so many branches).

The tree is mostly kept indoors but it's been outside for the last couple of weeks. I brought it indoors again to give it a break from the unending rain (fairly constant for the last few days), which is when I noticed the fungus/mould.

All advice I've seen for handling fungus is to cut back the infected branches but the infection is all on the main trunk. Is there a way to handle this fungus? I’m struggling even just to identify it. Are there fungicides that won't kill the tree? I have attached two pictures of the fungus and one picture of the tree overall.

I am in the west of Scotland.

Image links below:

Tree:
Detail:
Detail:

Put it out and leave it out rain will do no harm it is quite natural. As for the possible fungus have you tried a toothbrush and vinegar? Cover the soil so none gets on it. This is the way to remove moss from the trunk so it might get rid. Stop fertiliser, it sounds as if it might not be alive, this may be the result of having it inside. I don't look at links so you need to post here. You might be near a club depending on where you are, I know there are several in Scotland but not knowing where you are can't say. Keep the tree watered but allow to almost dry between watering. If you are concerned about too much water then put it under a table or similar. Geoff.

Managed to see the pictures, the soil looks very poor. It is very dull where you have it, The tree needs light and that is not enough by a long way. You can see this by the way it is growing, It is too soon to re pot into good soil as you have just done it unless the soil is so compacted that it is not draining. If the water sits on the top of the soil for more than 30 seconds it is not draining and it may be that the soil underneath is not getting much water. Try a chopstick test to see if the soil is dry, push a chopstick into the soil and if it comes out clean it is too dry.

Thank you for this, I'm give it a scrub with vinegar. The tree is also back outside. That's a south facing window so that's as much light as an indoor bonsai in Scotland is getting.

What soil mix do you recommend? That is akadama and clay.

I would recommend leaving it outside. Plants typically can deal with the concept of rain.

I will not follow external links to pictures; Please post them directly on the forum. This will also ensure the images are available to other people searching for answers / information at a later time. So I cannot tell what is on the trunk.

leatherback wrote:

I would recommend leaving it outside. Plants typically can deal with the concept of rain.

I will not follow external links to pictures; Please post them directly on the forum. This will also ensure the images are available to other people searching for answers / information at a later time. So I cannot tell what is on the trunk.

That is true which is why all plants can survive in all climates.

I've used BBCode to post the pictures.

Cheers for the advice so far, I've tried scrubbing the spots with vinegar and they won't budge. But now I'm not actually sure it is mould at all, it looks like raised spots of the underlying wood.

As for the soil, the water doesn't pool so I don't think it's compacted, especially compared to some other plants I have potted in other soils.

There's new foliage growing and it isn't losing leaves so I don't think it's dead yet.


Edit: I've tried attaching images directly to the forum, they're showing up in the preview but not the forum proper.

Ill have a go when I get back to a laptop.

I am not sure there is anything to worry about, it certainly won't kill it. If the soil is draining then I would say again don't worry about it. But then when next re potting I would get some decent soil for the tree.

Will do. I've also potted the tree a bit crooked as well which is going to bother me until it's repotting time again but it's a learning experience. Shame if it's not good soil, I like the company I bought it from.

In case anyone sees this and wants to know what it is, I think they are just lenticels: rollacity.org/reforest/forms/Elm.pdf