Acer Palmatum leaves curling, possible infection?

[Palmatum]

I have a green leaf Japanese maple (my first bonsai) whose leaves have been curling. I originally thought it was underwatering, but I'm now afraid it might be an infection. Could it be an infection?

Timeline:
- Mid-December - Bought plant. Watering schedule is once a week, in partial sun.
- Jan 1 - Last time plant was noticed fully healthy (similar to picture below)
- Jan 6 - Was going to water according to usual schedule. First noticed curled leaves (already curled same amount as in pictures below), thought it was just underwatering or heat stress. Bottom watered and moved to a shadier area that still has partial sun.
- Jan 7-9 - Monitoring. Leaves not curling more, but not recovering either. Still green, but slightly losing color over the days.
- Jan 9 - Quick (5-10 mins) of bottom watering.
- Jan 10 - Pictures taken below. Stems still green underneath (green circle), still alive. First noticed possible infection. Black spots on bark/death of cambium (red circles), not sure if these were here before. Powdery mildew on some leaves (orange circles) that were not here last Jan 7. Sprayed baking soda/soap/water mixture lightly on leaves.

Area: Philippines*
*only have wet/dry seasons, no winter. December/January is a cool dry season here.

Does this look like just underwatering + powdery mildew? Or is it bacterial/fungal infection? And do I just keep watering every few days, spraying baking soda/soap/water mixture once a week, keeping in a shadier area, and hope for the better? What else should I try - do I need to check the roots, remove the black bark, move to a larger pot, etc.?

I've been taking care of plants for a while now, but this is my first bonsai and my favorite plant. I've actually cried a couple of times worrying she might die. Please, how do I save her?

 

[pandacular]

Welcome to the forum! You can learn a lot on here if you stick around. If you wouldn’t mind, please visit your profile to update your location and ideally a USDA zone.

Is this tree permanently inside or was it just taken inside for photos?

 

[Palmatum]

Hi! It's been kept inside in partial sun (next to a window, bright but usually never too hot since sun doesn't directly hit window) since I got it since I live in a condo.

 

[hardtimes]

needs to be outside

 

[rockm]

Hi! It's been kept inside in partial sun (next to a window, bright but usually never too hot since sun doesn't directly hit window) since I got it since I live in a condo.

The tree looks to have a root problem, which is the result of watering and overall poor health. Maples will not survive very long inside. The curled leaves are dried out because the roots are not moving moisture up to them. Dead roots can be the result of too much water or not enough. Inside, the tree is also subject to extremely low light, low humidity (if you have air conditioning) and very little air circulation. Compounding the issue is maples require a cold dormancy period (they're from areas that get winter).

A better choice for 'indoor' bonsai are tropical species like ficus and schefflera. If you're in the Philippines, those species should be pretty common as bonsai.

 

[Palmatum]

Thanks everyone!

I inspected the roots before moving it to an outdoor area with partial sun. The roots could be in better shape, but thankfully it doesn't appear to be root rot. Several of the dark roots here have very fine white tips, though there aren't a lot, which is concerning. Do these roots appear okay?

I don't have air conditioning, but it was receiving little air circulation indoors. I'm also not sure how long it'll actually live given that we have no winter for dormancy period (USDA hardiness zone 13), but I'll try to keep it alive for as long as possible. It was raised in a part of the country averaging ~27°C, and the area I currently live in averages ~27°C in cooler months and ~35°C in warmer months. I've only heard of few long-term Japanese maples in the Philippines, particularly in those colder parts with ~27°C.

The dark spots on the bark also grew larger today and appear to come off like dust, which seems to be sooty mold. Should I be concerned or should I wait and observe if it goes away now that she's been moved outdoors with better circulation?

 

[ajm55555]

The tree is dead. Black spots on the trunk are never a good sign.
These types of deciduous trees cannot live in a tropical zone like yours. They can survive for a few years but in the end they are doomed.
They can stay inside during the warm months (always better outside though) but they need a dormant period that only temperate zones can provide.

 

[CarpenterDiaz7]

The trees roots look like they may be waterlogged, but after reading your second post I see that it will never have its dormancy period as any deciduous tree should have which means the tree will weaken or already is and a weak tree will not survive long. Try a species that is native to where you live, this is the best practice to have a living tree.

 

[ajm55555]

The trees roots look like they may be waterlogged, but after reading your second post I see that it will never have its dormancy period as any deciduous tree should have which means the tree will weaken or already is and a weak tree will not survive long. Try a species that is native to where you live, this is the best practice to have a living tree.

There are tropical deciduous trees that lose the leaves "in response not to seasonal temperature variations but to seasonal rainfall patterns" [Wikipedia] but the Japanese maple is not one of them.