Beginner with Japanese Maple troubles

[Omar]

Hello all,

It seems yet another noobie is in search of guidance : ]

I bought my JM ~ 3 months ago, the first week in July. It's progressing nicely with the exception of what seems to be some sort of white powder that's accumulated on some of the leaves. Is this simply cosmetic or can it pose detrimental to the plant's health?

Some background info:

I live in NYC, the plant stays outdoors on my fire escape (not ideal of course but as the young kids says YOLO haha)

I water in the morning before I leave for work, around 5:30AM. I use super thrive and a liquid fertilizer sparingly, usually once a week every Sunday.

I don't mist the leaves since i'm not sure if this is a fungal infestation and do not want to risk further contamination if it is.

It's given partial shade by a nearby Zelkova neighbor.

If anyone here has any experience with the same issue or any insight, i'd be most grateful.

Many thanks for your time,

Omar

 

[JoeR]

A few of mine have the same thing. I just assumed it was hard water buildup but I don't really know.

 

[Eric Group]

Powdery Mildew maybe
Could also be lace bug, but that looks more like a powdery build up on the leaf than damage from something getting the leaves.

 

[aml1014]

Looks to be powdery mildew to me as well if it spreads treat with copper sulfate and remove affected leaves.

 

[Bunjeh]

You should be fine. However, if you like maples, try Trident. They are much more tolerant of urban conditions.

 

[sorce]

I dig the fire escape!

Welcome to Crazy!

Sorce

 

[Omar]

Thank you all so much for your input, very much appreciated.

 

[Omar]

I dig the fire escape!

Welcome to Crazy!

Sorce

Haha thanks! I haven't quite thought about what happens come winter...

 

[sorce]

Haha thanks! I haven't quite thought about what happens come winter...

You could Probly throw em in a sterlite joint. To keep the wind off.

Sorce

 

[GrimLore]

In our area 6b "if" we encounter that "look" and we are positive it is not an insect we use copper fungicide as it is fungal. If that is the case give them a good spray now and when they are jusstarting to push buds in Spring. After that read the directions and follow up with treament which is most often bi-weekly. Again, be certain it is not insects which seem to show up in boat loads here in the North East when we approach Fall.

Grimmy

 

[Leo in N E Illinois]

Agree with the others, powdery mildew, which given the fire escape has excellent air movement, should not be life threatening to the maple. JM is moderately tolerant of powdery mildew. So what to treat with? Copper sulfate is often recommended, but you need to read labels at the local box store to find one. Roses are very susceptible to powdery mildew. Look for a rose spray labeled for powdery mildew. Rose sprays are at most box stores, you should have no trouble finding one that will work.

 

[Dav4]

Haha thanks! I haven't quite thought about what happens come winter...

The powdery mildew is honestly not an issue for your tree...but the lack of a plan for winter most assuredly is. Unprotected on a fire escape in Brooklyn, NY through a winter that's predicted potentially to be as bad as the last one will probably result in a dead tree come spring time. It's going to need a fair amount of protection to make it.

 

[ColinFraser]

I haven't quite thought about what happens come winter...

. . . or a fire.

 

[M. Frary]

The powdery mildew is honestly not an issue for your tree...but the lack of a plan for winter most assuredly is. Unprotected on a fire escape in Brooklyn, NY through a winter that's predicted potentially to be as bad as the last one will probably result in a dead tree come spring time. It's going to need a fair amount of protection to make it.

You need to quit saying that. We are having El Nino weather this winter!
I hope.

 

[ColinFraser]

You need to quit saying that. We are having El Nino weather this winter!
I hope.

Hope for the best; prepare for the worst

 

[M. Frary]

Hope for the best; prepare for the worst

I always do. Last winter it was colder here at times than it was in Alaska.

 

[Leo in N E Illinois]

For balcony bonsai, I have seen some use a cheap, but large enough for the tree styrofoam cooler. Pick up a cheap cooler. Punch a few holes in bottom so it doesn't fill up with water, from your watering or from melted snow. Place tree in bottom of cooler. Fill around tree with styrofoam peanuts, or leaves or some just leave empty. Once weather is below freezing, put the lid on, tape it on so wind doesn't blow it away. You're set. The cooler will cool to average outdoor temperature, but it won't do the rapid freeze thaw that you would get on a balcony. It works with trees that are fully hardy in your growing zone, though it is more reliable if the trees are hardy at least one zone colder than the zone you are in. Key with winter survival. Let the freeze once, and stay frozen all winter. Check regularly - in deep cold, once a week is enough - check regularly to see if water is needed.

I've seen people make this work. Some at a small number of air vent holes around the sides of the cooler, but don't add too many, or you will get more rapidly fluctuating temperatures.

When temperatures vary more than 20 degrees in less than 24 to 48 hours is when freeze damage tends to happen. Going from 42 F one day to -5 F that night is far more damaging than going from +10 F to -5 F. Even though the tree might be hardy to -20F the 42 to -5 F change is very likely to cause damage, where the +10F to -5 F in 24 hours is unlikely to bother a -20 hardy tree at all.

Cooler will slow the temperature changes. The tree won't warm up too fast, or cool down too fast. Cooler will protect from short term plunges into the deep freeze.

The bigger the cooler, or the "thermal mass" of what is inside the cooler, the slower the temperature changes inside the cooler. If you have only a couple trees in there. Put a couple plastic milk jugs filled 3/4 with water. The water will provide thermal mass, once frozen, will help keep trees frozen. And when liquid, will slow the rate of cooling inside the cooler.

 

[aml1014]

For balcony bonsai, I have seen some use a cheap, but large enough for the tree styrofoam cooler. Pick up a cheap cooler. Punch a few holes in bottom so it doesn't fill up with water, from your watering or from melted snow. Place tree in bottom of cooler. Fill around tree with styrofoam peanuts, or leaves or some just leave empty. Once weather is below freezing, put the lid on, tape it on so wind doesn't blow it away. You're set. The cooler will cool to average outdoor temperature, but it won't do the rapid freeze thaw that you would get on a balcony. It works with trees that are fully hardy in your growing zone, though it is more reliable if the trees are hardy at least one zone colder than the zone you are in. Key with winter survival. Let the freeze once, and stay frozen all winter. Check regularly - in deep cold, once a week is enough - check regularly to see if water is needed.

I've seen people make this work. Some at a small number of air vent holes around the sides of the cooler, but don't add too many, or you will get more rapidly fluctuating temperatures.

When temperatures vary more than 20 degrees in less than 24 to 48 hours is when freeze damage tends to happen. Going from 42 F one day to -5 F that night is far more damaging than going from +10 F to -5 F. Even though the tree might be hardy to -20F the 42 to -5 F change is very likely to cause damage, where the +10F to -5 F in 24 hours is unlikely to bother a -20 hardy tree at all.

Cooler will slow the temperature changes. The tree won't warm up too fast, or cool down too fast. Cooler will protect from short term plunges into the deep freeze.

The bigger the cooler, or the "thermal mass" of what is inside the cooler, the slower the temperature changes inside the cooler. If you have only a couple trees in there. Put a couple plastic milk jugs filled 3/4 with water. The water will provide thermal mass, once frozen, will help keep trees frozen. And when liquid, will slow the rate of cooling inside the cooler.

Here in new mexico we regulary have for instance today at 7 am it was 27° and now being 1pm its exactly 30° more at 57°. I love the beauty of where I live, but I really hate the weather lol.

Aaron

 

[Cypress187]

How is this plant doing? I had mildew on my birch, i used some natural spices stuff (really bad smell) but it worked!

 

[Omar]

For balcony bonsai, I have seen some use a cheap, but large enough for the tree styrofoam cooler. Pick up a cheap cooler. Punch a few holes in bottom so it doesn't fill up with water, from your watering or from melted snow. Place tree in bottom of cooler. Fill around tree with styrofoam peanuts, or leaves or some just leave empty. Once weather is below freezing, put the lid on, tape it on so wind doesn't blow it away. You're set. The cooler will cool to average outdoor temperature, but it won't do the rapid freeze thaw that you would get on a balcony. It works with trees that are fully hardy in your growing zone, though it is more reliable if the trees are hardy at least one zone colder than the zone you are in. Key with winter survival. Let the freeze once, and stay frozen all winter. Check regularly - in deep cold, once a week is enough - check regularly to see if water is needed.

I've seen people make this work. Some at a small number of air vent holes around the sides of the cooler, but don't add too many, or you will get more rapidly fluctuating temperatures.

When temperatures vary more than 20 degrees in less than 24 to 48 hours is when freeze damage tends to happen. Going from 42 F one day to -5 F that night is far more damaging than going from +10 F to -5 F. Even though the tree might be hardy to -20F the 42 to -5 F change is very likely to cause damage, where the +10F to -5 F in 24 hours is unlikely to bother a -20 hardy tree at all.

Cooler will slow the temperature changes. The tree won't warm up too fast, or cool down too fast. Cooler will protect from short term plunges into the deep freeze.

The bigger the cooler, or the "thermal mass" of what is inside the cooler, the slower the temperature changes inside the cooler. If you have only a couple trees in there. Put a couple plastic milk jugs filled 3/4 with water. The water will provide thermal mass, once frozen, will help keep trees frozen. And when liquid, will slow the rate of cooling inside the cooler.

This is brilliant, many thanks for the suggestion!