Maple problems...help appreciated

August44

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Hello. I am a bit new to this as you know and this is the first year with maples. I have some Amur maples, one specimen one, a clump. and a forest. Some of the leaves on them are fringed in white as you can see in the pictures. Also some of the very small leaves are almost 50% white. Is this a problem or normal. They are in dappled morning sun, in good bonsai soil and watered regularly. Then I have one acer palmatum that seems to sit there in the same area same soil etc with wilting leaves with some of them finally just wilting badly and falling off. I have pots of the same species and a forest pot of the same species in the same section that are fine. Originally the tree was just fine and showed no signs of problems, but now we have what you see in the two pictures. I am tempted to chuck the one and move on, but would like to learn something so will wait. Thanks, Peter
 

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August44

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And Sorce don't come on here and tell me that is fairy dust either...I'm serious! ;)
 

0soyoung

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The palmatum looks like inadequate roots. This happens when one has been overly aggressive with root pruning, for example. Suffocating roots (to wet / inadequate oxygen) looks similar and often happens when deeply overpotted. Regardless, the remedies all require full shade and lots of patience. Also sprinkling the foliage during the heat of the day in the afternoon may be needed. Also, stick your finger into the substrate (maybe in the corner of the box) and wiggle right on down to the bottom to see how wet it really is. If it is really wet, reduce your watering frequency and maybe elevate one side of the box for a week, say, then another side and keep doing this until it perks up. It could take most of this season to recover.

I'm unfamiliar with the amur's leaf problem at this time of year. It wouldn't be unusual to see this at the end of the growing season. Amurs are sun pigs! They will abandon leaves that are shaded by another leaf in short order, the entire leaf turning yellow to whitish before it drops. However, this isn't your pictured leaves.
If it is fungal, old leaves are most likely just spore sources for continuing infection. You can watch the newly emerging leaves - if they develop the same discoloration we'll know it is fungal. Fungus SOP is remove the affected leaves and spray. If, on the other hand, new leaves don't similarly discolor, the problem is due to something that happened earlier this spring - review.
Amur will produce a second flush in a season, so you could just remove the affected leaves by cutting the petioles. The petiole stubs will fall away in a few weeks and new leaves will emerge afterward.
 

August44

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Oso...New leaves are also discolored on the Amur. I would just about have to defoliate the tree to get rid of them at this point. If I spray without removing affected leaves will that get rid of the problem? The leaves look very healthy and I am not loosing any either. Thanks, Peter
 

Wires_Guy_wires

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Let me start off by stating I know next to nothing about maples.

But I do know plant pathogens! It seems there's something raging in the first maple, the typical mosaic is something I know from... Mosaic viruses. Most plants survive them pretty much unharmed, it comes and goes and it can be gone forever when the leaves shed in fall and the dropped foliage is removed. Sometimes the virus goes dormant and can hide for decades. But it's not an attractive thing to look at in the mean time. These viruses spread through aphids and other sap-munching insects, so if it is in fact a virus, you should keep it away from the other maples. To my knowledge, there are no existing anti-virals for plants. Antibiotics are not going to help, but insecticides might contain the spread by killing all aphids that take up the virus. Can you get rid of a virus like that? Practically, no.

Maples - field maples specifically - are mentioned in the wikipedia about ApMV, the apple mosaic virus: https://en.wikipedia.org/wiki/Apple_mosaic_virus
 

0soyoung

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Oso...New leaves are also discolored on the Amur. I would just about have to defoliate the tree to get rid of them at this point. If I spray without removing affected leaves will that get rid of the problem? The leaves look very healthy and I am not loosing any either. Thanks, Peter
What I see only seems unusual because of the time of year.
I would be watching new shoots and whether they develop the same appearance or not. The simplest outcome is that they do not, which would mean that the 'bad' ones are just a cosmetic problem and can stay. Otherwise, you've got trouble that needs prompt attention.

Maybe they exist, but it is news to me that there are variegated amur maples.
 
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