I have 4 year old Jumbolan bonsai now its green leaves new and old are turning black just like when you put excessive manure in normal plants.
similar like this:
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In order to try helping you with this problem I´m posting an image with the main/most usual problems that might occur to a tree´s leaves. The picture itself is written in Spanish, but I´m posting its translation here for you to understand it. Oh, the first 2 cases correspond to new leaves growth and the next 6 examples correspond to older or established leaves. (That is what the black line separates)
Hope this helps,
#1 Severe Nitrogen deficiency.
Small new leaves presenting a white/yellow coloration.
#2 Calcium deficiency
New pale and wrinkled growths (It could also be an overdose of potassium, magnesium)
#3 Iron Deficiency
Greenish nerves and old yellowish leaves
#4 Phosphate Deficiency (Phosphorus)
Older leaves presenting a yellow color with dark spots. The leaves die and fall rapidly (Note the similarity to early nitrogen deficiency)
#5 Magnesium Deficiency
Dark veins and old leaves with an extreme light green tint or shade
#6 Normal Leaf
#7 Early Signs of Nitrogen Deficiency.
Older leaves turn yellow, die and fall
#8 Potassium Deficiency
Very small holes with yellowish edges.
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So, looking at your first picture and comparing with the list of possible problems I´m leaning to think it matches with item #7: Early Signs of Nitrogen Deficiency.
So, what you could probably do it´s to feed your plant with a fertilizer. The amount and frequency of the "treatment" would depend on the species, the fertilizer itself and the current season of the year. (Just follow the manufacturer instructions)
So, looking at your first picture and comparing with the list of possible problems I´m leaning to think it matches with item #7: Early Signs of Nitrogen Deficiency.
Very useful post, I will keep that for my own reference.
However, if it was nitrogen deficiency, I would not expect the two spots. To me it looks like an infection, maybe a bacteria:
"The symptoms of bacterial spot are quite different from other diseases of stone fruits. They may be confused with nitrogen deficiency"
However, if it was nitrogen deficiency, I would not expect the two spots
Sorry Auk, but I don't seem to see those two spots you are referring to. In the first picture I see no spots at all
Now, that said, after reading your first link I see that stone fruit trees are actually prone to suffer this kind of infestation, so I think I might have discarded other causes too fast and a bacterial disease could be present as well.
Basically, what you read here means: No-one has a clue what it might be. There is too little information to make an informed choice of what is causing this.
- Have you recentely repotten?
- Changes fertilizing?
- where does it stand?
Have you checked whether you see any insects roaming around on the leaves?
I would choose in the area of bacterial, or perhaps fungal, infection of the stems/sapwood. This sort of die-off you often see in shrubs with a fungal infection in the phloem. But as IO do not know the circumstances, nor the species of plant you have there.. It is guessing for me too.