Sharps pygmy japanese maple spots on leaves

I purchased two beautiful sharps pygmy japanese maples in nursery pots this spring. One of them I potted up in an oversized bonsai pot with akadama and pumice and pruned ~50% of the roots. That one is doing wonderfully.

The other one I left in the nursery pot and did some minor pruning to the top of the tree. I didn’t want to do any major styling on either tree in order to get a feel for it’s growth and health during the first year of having it.

The one in the nursery pot was looking great up until today when I noticed it has lots of tiny brown spots speckled on the leaves of about half of the trees branches. Ive done some searching online but haven’t found any examples of small spots just like these.

I have not been watering the one in the nursery pot as much as the one in akadama. I don’t think it has been over watered.

Should I be worried? Fungus, sun damage?

Thanks in advance for any advice

Not an expert but I would be thinking fungal, is it staying too wet. Personally i would try to balance the water and oxygen for 2 weeks and asses where it is at.

Would you try spraying it with a fungicide?

Personally I would wait, I first give proper water/o2 balancing a chance. Likely keep it on the dryer side than it had been leading up to the situation (but not too dry being a Japanese Maple). I literally just had this with 2 Chinese elms. Took about 10days to see a change with more attentive watering. I also basically asked a more experienced member the same thing…So I am basically just re-phrasing what he told me and it worked. I typically try to avoid using chemicals, unless I am out of options or the problem is too far gone. So you have some sense of perspective to this line of thought.

Again I am not an expert, very far from it… but I don’t believe this type of fungus lives on the leaf tissue but either is starting at the roots or in the xylem tissue!

Are the ‘spots’ actualy black necrotic fungal spots; or, purple pigment areas…? The photo looks like the latter…

Thank you for the info NEbeech.

As for the spots, they are not purple or black really, more of a brown/gray

Here is a picture of some newer interior leaves:

Did you fertilize this tree? Looks more like “burn” sun, wind or fertilizer. Good question Kurt!

I did not fertilize it yet. It is possible that it is sun damage, but the really small spots in the first picture I posted gave me pause because that didn’t look like leaf burn from the sun to me.

Well, I’m sorry to say that it got worse. Much worse. Just last night I removed most of the damaged leaves and sprayed it with bioadvance 3 in 1.

Today it looks WORSE than it did before I removed the damaged leaves. How could removing the bad leaves cause almost all of the good leaves to become just as bad overnight?

I’m beginning to think the bioadvance 3 in 1 damaged the leaves, but I can’t be sure.

In any case, from what I can find online I believe this is anthracnose. I cut off about a 3mm thick tip off of a branch and didn’t see any signs of verticallum wilt in the cross section. But I’m no expert.

I really, really don’t want to lose this maple. Out of all of the plants I have, this is the one I want to keep the most.

At this point I don’t know what to do.

Hello there, just out of curiosity where do you live? Also, that one picture looks like you keep it under a tree, is that the case? I had similar looking spots on my maples when kept directly under the canopy of a large Live Oak (one died because I left it there). Something about these trees release pathogens and fungus that just drip/drop right onto the thinner cuticle leaves of maples like this and wreck havoc. While they do need shade, a clean shade (especially for container grown maples) is important. What I mean by that is try a good 40% shade cloth or so positioned in an otherwise sunny area; this will ensure adequate length of sun exposure throughout the day for a strong healthy tree but temper it so it’s not as intense (if that makes sense). The shade provided is clean in that it does not harbor pest and disease that literally rain down on your trees. Looking at the table your maple is on it looks like some debris is falling from the tree overhead…this could be the source of your problem as it was mine. Just a thought and worth a try I think!

Thank you for the reply, and good eye!

Yes, my backyard has a large ash tree that rains down dead flowers like crazy. I would not be surprised if that is what started this problem, but it’s current location is where I put it today to keep it out of the heavy sun/heat we are getting tomorrow in Massachusetts. It was in the driveway previously away from the majority of the falling debris.

I’m not sure whether I should be giving it more sun to help kill the fungus, or less so that the weakened leaves don’t dry out. I’m guessing the latter which is why I have it in shade now.

I do need to get a shade cloth.

Really hoping this one makes it. Any advice moving forward? Little known miracle cure passed down through generations by chance?


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Oh ok, I got yah. I would definitely make sure it gets some sun, maybe a morning sun spot if you have it? At least until you get a good spot with shade cloth up away from the bigger tree debris. As for a fungal remedy, you could try a water spray with very dilute vinegar in it. I wouldn’t add much, maybe even test the pH to make sure it’s no less than like like 5 or so. I’ve been using vinegar (distilled white %5 from the grocery store) to drop the pH of my water for the eden blue gold products (they recommend 6.4pH for water to allow optimal nutrient uptake) and the plants seems to love it. I guess what I’m trying to get at is this vinegar spray will not hurt the tree once diluted and should help with any fungal problems while also serving an added benefit of helping out your tree with nutrient absorption thus also theoretically making it more disease resistant by helping its immune system. Let me know what you decide and keep me posted! Totally your call.

I will try that, thank you so much for the advice! I appreciate it.

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Of course, let me know! Also, make sure you don’t over shade it, they do get their strength ultimately from the sun…and sometimes we can love things to death. The sun like you mentioned (in careful amounts) could possibly even help. Good luck, I really hope this turns around. I’ll be lurking for updates!

I am also in MA and I have had a few jap maples in my landscape have similar dieback this season, not sure if it’s in obvious weather related conditions. Definitely shade today with it jumping into the 90’s. My first thought about things getting worse is the insecticide pesticide was the input that caused this not the removal of the leaves. I would personally go hands off, balance of water and oxygen and let the tree do what it needs to do. Continuing to add more variables (treating/doing) when we don’t know what is going on is more like to make the promblem worse than accidentally stumble across the solution.

As mentioned morning sun, no overhead watering and air movement will be your best approaches, I have the same problem with my dwarf maple. With fungicides I was never able to control the problem the horticulture will have more influence. Most fungal spores need an amount if time that leaves stay wet too germinate that is what you want to reduce especially on young leaves.