Issue with Japanese Maple

[TimS]

Hey all, I have a large old Japanese Maple that was very unhealthy at the end up summer and i discovered the soil had broken down to the point of just simply holding water permanently rather than draining away. The new leaves would come out and immediately shrivel up.

As soon as the tree went dormant i repotted it and removed as much of the old soil as possible (at least 90%+) but did not root prune it to try to avoid stressing it. It has leafed out in spring but the older leaves are still showing some signs of some kind of trouble. The pot it was in was extremely shallow so i have placed it in a pot that is double the depth but about the same width.

The water drains beautifully now, sunlight until around about 2pm and no watering of leaves that would cause the scorch. It had aphids briefly at the start of spring but i have dealt with those, and there are no other pets to speak of i can see.

Any ideas? It is greatly improved over how unhealthy it was, but it is still not 100%.

Photo of what the older leaves are doing

[Watto]

Tim, maybe a photo of the whole tree would be of assistance if you could?

[TimS]

Here are more photos that will hopefully be of assistance. Just quick phone photos so they are pretty average

Whole tree: I let it run this year to try to get it regaining strength that's why it looks like a shrub not a bonsai


Old leaves browning and curling:


New shoots looking healthy:

[dansai]

When you say you did not prune it, do you mean you didn't prune the roots?

[TimS]

Yes i did not prune the roots as i didn't want to stress it further when i was already struggling. The pot it was in was about 2-3cm deep at most so I've just cleared the old soil out and put in in a deeper pot.

I didn't pinch the shoots as they came out in spring to let it run and regain vigor.

[Akhi]

I used to get that on my JM which were healthy and I attributed it to sun and wind damage don’t think it’s a root issue as the tree is generally looking healthy.


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[treeman]

It could be fertilizer burn. They need very little, especially in repotting years. I have still not fed any of mine since last summer and they are thriving and clean.

[TimS]

Thanks Treeman, you could be on the right track there. I mixed some blood and bone into my bonsai mix and might have been a little heavy handed. Also placed a couple of slow release tablets in the pot too so the combination might have been excessive for the tree.

Given the new shoots are looking healthy and not turning black as soon as they come out like they were when it was waterlogged last summer i'm satisfied it's not an excessive water issue and the excessive fertiliser makes sense. Straight water for it from now on and hope it flushes out any excess over time.