Prunus - should I be concerned about these leaf changes?

[Beano]

Hi,

I bought this flowering plum from SA bonsai show a few months ago. I’m not sure but I think it might be a prunus cerasifera? It was leafing out fine but in the last week some of the leaves have changed to autumn colour with spots and there are some spots on the green leaves as well.

I’m not sure about the roots or mix since it was pushing growth when I bought it so not repotted by me. It’s on my slat wall near the top so it gets most of the days sun. Watering is once per day for 30min via drip/trickle system (fast flow). There are no signs of wilting during the day so I assume watering is adequate. For scale, the pot is about the size of a Christmas pudding.

It went a bit cold again last week in Adelaide, is it just colour change from temperature do you think?



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[shibui]

So far it is only a couple of the oldest leaves that are coloring so nothing to really worry about.
Could be nutrient related - something like nitrogen shortage as the trees can move N from old leaves to new growth if they are short. Consider fert if you have not been using additional nutrients regularly.
Spots on leaves are likely to be fungal but unless it gets worse I would not bother with treatment.
Does not sound like water as you haven't seen wilting and new tips are not affected.
Too much sun would also likely show up on outer leaves and tips before oldest leaves.
I really doubt that it has been cold enough to affect leaves.

[Beano]

Thanks Shibui!


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[Beano]

Sorry, I uploaded 2 pics but the 2nd one isn’t there…

Close up:



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[Akhi]

If my guess is right it’s receiving too much sun. I had a similar thing happen to mine and I have moved it to part shade now