Young Japanese maples: Root rot? Sun damage? Both? Need some help…

[rdb00]

I’m trying to identify what’s wrong with these younger Japanese maples I have. I had them shipped from a similar zone (7) a few weeks back and I knew they would need to acclimate to their new home but they have gotten objectively worse the last week or so and naturally I am concerned.

I am using carbon purified water with a tiny amount of vinegar to bring pH for watering to around 6-7 (my normal water pH is 9-10). I have been keeping them in morning sun under an awning in Front of my house (south facing). When I first started seeing browning, I tried to reduce the direct sunlight they were getting. No improvement yet. I have also been consistently watering once daily after work ~4-5pm. I don’t think I am overwatering because the top half inch or so of soil is dry. I haven’t increased the amount I am watering.

I have attached some pictures. The first pics are when I first got them, the subsequent pics are progressive worsening.

Any troubleshooting insight would be much appreciated.

 

[Mike Westervelt]

They look fine to me, perhaps a little mechanical damage due to shipping.

With regard to the color, most JM spring growth comes out a different color than their eventual summer color.

 

[rdb00]

They look fine to me, perhaps a little mechanical damage due to shipping.

With regard to the color, most JM spring growth comes out a different color than their eventual summer color.

Thank you for the reassurance

 

[AndrewBigwood]

I own 2 green dream acers(amongst others) that are suffering from what could be a similar issue to yours.
My current thoughts focus on the branches that I cut back, and the knock on effect of those cuts.
The die back seems to affect certain JMs more than others.
The dead leaves I have appear to be a consequence of this cut back issue.

I've also found through growing a crop of JM seedlings that if they're in organic soil, they don't like being over watered.
Hope this helps.

 

[Shibui]

Agree that these trees look very healthy. Some burnt leaves seem to be par for the course when growing Japanese maples but, fortunately, some damaged leaves does not seem to worry them.
Those seedlings are in relatively small pots. Likely to dry out fairly quick so if anything I would say dehydration is far more likely than overwatering, especially when you are aware and likely underwatering to compensate for possible overwatering. Deeper pots also less likely to suffer from overwatering than shallow ones.
Damage from overwatering takes weeks or months of constant soggy soil to manifest. A few days or even a few weeks is not long enough to be seeing problems.

 

[rdb00]

I own 2 green dream acers(amongst others) that are suffering from what could be a similar issue to yours.
My current thoughts focus on the branches that I cut back, and the knock on effect of those cuts.
The die back seems to affect certain JMs more than others.
The dead leaves I have appear to be a consequence of this cut back issue.

I've also found through growing a crop of JM seedlings that if they're in organic soil, they don't like being over watered.
Hope this helps.

I may honestly be overwatering than because I haven’t done any pruning

 

[rdb00]

Agree that these trees look very healthy. Some burnt leaves seem to be par for the course when growing Japanese maples but, fortunately, some damaged leaves does not seem to worry them.
Those seedlings are in relatively small pots. Likely to dry out fairly quick so if anything I would say dehydration is far more likely than overwatering, especially when you are aware and likely underwatering to compensate for possible overwatering. Deeper pots also less likely to suffer from overwatering than shallow ones.
Damage from overwatering takes weeks or months of constant soggy soil to manifest. A few days or even a few weeks is not long enough to be seeing problems.

Thank you for your insight, I did consider slip potting because the smaller pots made me nervous. But I ultimately didn’t because I wasn’t confident I could match the nursery soil well enough to make it work until I could do formal repot

 

[rdb00]

Quick update in case someone comes across this thread... I noticed black shoots that were tucked behind overgrowth on another tree I purchased around the same time (Katsura JM). After some research this appears to be likely secondary to Pseudomonas spp and the black spots can also be seen on the trunk at the base of the tree. I am within the return window for the visibly impacted tree so I will definitely be returning for some credit, but I did touch my younger maples after having handled the infected older one. I will post updates on how the younger ones are doing. Hoping I get lucky and didn't cross contaminate.

Kicking my behind because I did actually notice the dark shoots at the nursery I got this from but I did some searching and it had me thinking it could be due to sun scorching. Lesson learned. If it is black, put it back (and probably let someone know)

 

[Jetson1950]

I had the same thing happen on a Sango KaKu JM I bought on line. When I got it I was surprised it was 5’ tall with a 1” trunk, but it arrived with large black areas of death on the branches and leaves. Contacted the seller and I advised them I was destroying the tree because I didn’t want it near my other maples and infect them. They refunded everything without question.

After I got refunded, I started thinking, well, bacterial infection. Just maybe I can save something. I cut everything above a foot off and tossed it. Took the stump out off its pot and presser washed the roots to remove all the dirt. Doused it with copper fungicide and put it in a new pot with fresh potting mix. Didn’t take it long before it said let’s grow leaves. Picture is about 3 weeks after I chopped the top off. I’ve already started trimming and pinching the little branched. I’ve got it in quarantine well away from everything else. If it continues doing well, I’ll put it in bonsai soil in a couple of weeks. It will stay in quarantine till fall to make sure it’s clean from the bacteria.

 

[Orion_metalhead]

I wouldnt repot it again this year. Just let it grow and repot it next spring.