Chinese Elm - Possible fungal infection.

[deeno]

I seem to have a problem with my Chinese Elm but I’m not exactly sure what it is and how to deal with it. It seems to be only a problem with the leaves which, as you can see in the pictures, have developed some black spots which then causes the leaf to turn yellow and die.

My trees have been sitting on the lawn and in partial shade up until about a month and a half ago so I thought it might have picked up a fungal infection from the ground. We’ve had some pretty humid weather lately as well.

How should I treat this, will defoliating help?

Thanks for your help.







Sent from my iPhone using Tapatalk

[shibui]

So many possible causes and so little background info to work with.
Fungal is possible but probably further down the list of possibilities.
To me nutrient deficiency would be more common. What is your fertilizer program? What potting mix?

I was also going to suggest that older leaves sometimes die but it appears the damaged leaves are not always the oldest ones so I can probably scrap that theory.

The black spots on some leaves does look a little like fungal infection but I have not seen it over here. Fungicide is readily available and does not cause damage if used even if the problem is not fungal so maybe a treatment could be applied. As I don't recognize the problem it is a bit hard to recommend any product but as leaves are affected fungicides aimed at leaf problems would seem appropriate.
Removing affected leaves is always a good strategy for fungal infection. If you remove leaves before they become infectious that can break the cycle. Bin or burn affected leaves to remove infective material.

The twigs look very long so I assume you have not been trimming new growth very much? Does that indicate a relative newbie to bonsai?

[deeno]

Thanks Shibui,

I would say I’m relatively new in Bonsai terms. I’ve only been playing around with them for about three years and chronic health issues have meant my learning process has been fairly slow and steady. I have quite a few trees that I’m developing in bigger pots and standard potting mix but nothing that’s in a Bonsai pot and this is the only one in anything that resembles Bonsai soil.

I’ve been an Ausbonsai member for a while and I like reading about and seeing everyone’s trees but haven’t really posted a lot. I’m hoping this year to be more involved as I have always really appreciated the community Ausbonsai is and the positive helpful attitude everyone has. I would like to start taking some of my trees to the next level and there’s no doubt that there is a huge amount of experience to tap into here, especially in Australian native trees which I’m especially interested in.

Sorry for the lack of information, I’ve had this tree since August 2019 when I got it as a supposedly 5 year old pre-bonsai and this is the first time I’ve seen these back spots. It’s been in a mix of 3mm river gravel, Attapulgite (absorbent clay,) and fine bark. I fertilise with Osmocote Native slow release and a 18-7.8-14.9 liquid fertiliser. I put a fresh dose of slow release about a month and a half ago and liquid fertiliser a couple of weeks back but it hasn’t had any liquid fertiliser for a while before that. I’ve just moved from Bunbury to Perth in January and it’s taken a bit to re-establish all the systems after the change.

I haven’t trimmed it much as I’m trying to let it grow as much as possible as it’s always been a slow grower. I actually posted a query last January about it seeming to be growing slow for a Chinese Elm and at that time you very helpfully suggested it might be a Catlin variety which has very long straight growth and is very slow growing which I think was right on the money. It has a very narrow trunk, no taper and no root flare as yet so I’m thinking I might pot it into a deeper and larger pot at the start of spring and leave it grow or consider an air layer or trunk chop.

I would be interested to hear some ideas. Here’s some more pictures.











Do you think it worth defoliating it and wait and see if it comes back or should I invest in the fungicide straight up?


Sent from my iPhone using Tapatalk

[shibui]

Try removing affected leaves first. It may make all the difference you need. It is good to only use chemical treatment as a last resort.
I have not seen black like that on leaves but think it unlikely that any leaf issue will actually kill the tree so you should have plenty of time to explore options.

This week I noticed some of my Chinese elms have reacted to the cooler weather and started to drop some leaves here. Perth should be warmer but this could just be a reaction to Autumn.
If it does lose leaves now it may not grow more before spring but unsure how it will react over there.

Catlin usually retains a lot of leaves through winter even here where it is cooler.
Good luck with getting increased trunk thickness even in a larger pot. I have just accepted that mine will be relatively thin trees.

[Akhi]

Have you considered nature taking its course and then once it is bare leaved in winter applying a fungicide which will clean up any spores? Or does that sound too lazy