Brown spotting on trident & Japanese maples

[Ghoulbath]

Hi all! I recently found some brown spotting on my trident and Japanese maples. We did have unexpectedly hot days last week, so I’m unsure if these spots are sun burn/leaf scorch or a fungal issue. Wondering if anyone has had experience and could tell me what they think it might be.

Thank you!

 

[NeedlesAndLeaves]

The overall health looks good.
I does not look like something fungal.
My maples have leaves with same spots.
If you had hot days that might have been the cause. Maple leaves are sensitive when it comes to sun, heat and dry winds.

Even if you keep the soil moist in summer this will happen in bright sun. The transportation of water will not be enough to compensate for the traspiration of water through the leaves. That is why they need (partial) during the warm days.

Keep it moist and avoid the hot sun

 

[NeedlesAndLeaves]

Adding your location will make it more easy for other people to help you

 

[Ghoulbath]

Adding your location will make it more easy for other people to help you

Ah, yes thanks. I’m in Connecticut

 

[zita]

Maple leaves are sensitive when it comes to sun, heat and dry winds.

yes

Even if you keep the soil moist in summer this will happen in bright sun. The transportation of water will not be enough to compensate for the traspiration of water through the leaves. That is why they need (partial) during the warm days.

Keep it moist and avoid the hot sun

no

key is to make the maple stronger, aka put it in full sun and let it get burned a couple of years. Then you get a tree that loves the sun and provides best colors too. Grows faster, less diseases.
Will take abuse much better and wounds will heal faster/better.

actually i do cut my maples in a way that every branch and leaves gets full sun all day long.

 

[RoadManDenDron]

yes

no

key is to make the maple stronger, aka put it in full sun and let it get burned a couple of years. Then you get a tree that loves the sun and provides best colors too. Grows faster, less diseases.
Will take abuse much better and wounds will heal faster/better.

actually i do cut my maples in a way that every branch and leaves gets full sun all day long.

Where abouts in the world are you located?

All fun sun is not equal

Please share some pics of you're super strong maples

I like to strengthen my trees with nutrition, and biostimulants

Some cultivars of JM are much more sun tolerant than others

 

[NeedlesAndLeaves]

yes

no

key is to make the maple stronger, aka put it in full sun and let it get burned a couple of years. Then you get a tree that loves the sun and provides best colors too. Grows faster, less diseases.
Will take abuse much better and wounds will heal faster/better.

actually i do cut my maples in a way that every branch and leaves gets full sun all day long.

I find this a strange advice to give on maples.
So you say that abusing the trees will make them stronger? Perhaps in some way.
But I think it is better to simply give the proper care.

Baking the shit out of maples is simply not their natural life. And will never be the best thing to do

 

[NeedlesAndLeaves]

And as @RoadManDenDron said your location could make a difference in advice given.

 

[NeedlesAndLeaves]

actually i do cut my maples in a way that every branch and leaves gets full sun all day long.

That is how we prune maples. Get light in to stimulate interior growth.
Full sun in Spring and Autumn yes.
But consciously letting maples in full sun to burn the leaves does not make sense to me when we are talking about BONSAI PURPOSES.

 

[doc spring _work]

Here in Utah those spots are indicative that your maples leaves got hit by water and sun, we find leaves are quite delicate and require a little protection and a careful hand with watering

 

[shohin_branches]

What is your fertilizer routine for this tree?

 

[NeedlesAndLeaves]

Here in Utah those spots are indicative that your maples leaves got hit by water and sun, we find leaves are quite delicate and require a little protection and a careful hand with watering

Thought this was a myth? Waterdroplets cannot magnify sunlight so much to cause burnmarks. Only on waxy or hairy leaves it can be possible.

Harry Harrington wrote an article about it. And I believe it was Bjorholm who mentioned that official research was done on this subject.

But salt or fertilizer dilluted in water and sprayed on the leaves is something else and can cause leaves to burn.

Maple leaves are indeed delicate.

 

[zita]

Where abouts in the world are you located?

south switzerland / north italy.......we do have very hot summers

Please share some pics of you're super strong maples

another day, promised

I like to strengthen my trees with nutrition, and biostimulants

+1

Some cultivars of JM are much more sun tolerant than others

i do own almost all of the well known cultivars, actually multiple of each from quite young to very old, and from very small to very big.
For multiple decades and different spots.

ALL of them, again ALL of them loves full sun all day long all season

consciously letting maples in full sun to burn the leaves does not make sense to me when we are talking about BONSAI PURPOSES.

you do not put it in sun to burn the leaves.

instead, you put it in sun and do not care about the few top leaves that might burn as the tree can handle it and after 2 or 3 seasons the tree will be sunprooved.
very especially for bonsais you want full sun as you get smaller leaves ...and branches do not die (loosing inner ramification)

So you say that abusing the trees will make them stronger?

you do not abuse the tree for abusing propose of course.
i am saying a sunprooved tree in full sun can handle the natural abusement of bonsaists much better, heals better, backbuds better, everything better, choose whatever from health to look.

Baking the shit out of maples is simply not their natural life.

exposing the tree to the elements is king

 

[Dav4]

Thought this was a myth? Waterdroplets cannot magnify sunlight so much to cause burnmarks. Only on waxy or hairy leaves it can be possible.

Harry Harrington wrote an article about it. And I believe it was Bjorholm who mentioned that official research was done on this subject.

But salt or fertilizer dilluted in water and sprayed on the leaves is something else and can cause leaves to burn.

Maple leaves are indeed delicate.

It is.

Fwiw, I was out watering/weeding the trees this morning and noticed similar spotted leaves on one of my "Bjorn" seedling clumps I started a 4-5 years ago. It get 6-7 hours of direct sun and is otherwise growing well. I'm not sure what is causing the blemishes (I suspect fungal) but I'm not worried and won't be changing anything.

 

[shohin_branches]

Thought this was a myth? Waterdroplets cannot magnify sunlight so much to cause burnmarks. Only on waxy or hairy leaves it can be possible.

Harry Harrington wrote an article about it. And I believe it was Bjorholm who mentioned that official research was done on this subject.

But salt or fertilizer dilluted in water and sprayed on the leaves is something else and can cause leaves to burn.

Maple leaves are indeed delicate.

Yep it is a myth. When I went to school for horticulture we had a whole unit on gardening myths and this was one of them. The focal point is not going to be on the leaf against the water droplet. Water also has a high amount of thermal capacity.

 

[RaginCajun]

I think it’s definitely heat related. I have three tridents. One is in a big cement tub, it was in full sun and got scorched bad when it was really hot (95 degrees actual, heat index well into the 100s). I moved it close to the other 2 and it’s exploding with new healthy growth. Now my tridents are in full sun until about 2:30-3pm and are then in the dappled shadow of my shade cloth. My Japanese maples in bonsai pots show the same signs under the 70% shade cloth all the time. My Japanese maples in cement tubs with promix soil in full sun with the tridents, shaded after 2:30pm are not showing any signs of trouble.
I have so many different species and they are are thriving. Japanese maples do great but it gets so hot down here, like it’ll be 90 degrees at 2am soon lol. Literally. Gotta watch them.

 

[RoadManDenDron]

you put it in sun and do not care about the few top leaves that might burn as the tree can handle it

I'm in the UK, we don't get really hot summers compared to the rest of the world

I have had maples completely crisp from too much sun and not enough shade, even in big pots with plenty of water

The same tree is now thriving under shade cloth

I was amazed it even came back in spring tbh, it lost all its leaves and made no effort to bud back last year at all,

I would definitely not recommend putting a tree through that, and for what it's worth the leaves were no stronger when it came out this year! Hence the shade cloth

 

[Ghoulbath]

What is your fertilizer routine for this tree?

I’ve only had the tree since March, but as of last month I did about a teaspoon of osmocote mixed in with the topsoil. So far been seeing new healthy growth what feels like weekly!

 

[doc spring _work]

Thought this was a myth? Waterdroplets cannot magnify sunlight so much to cause burnmarks. Only on waxy or hairy leaves it can be possible.

But salt or fertilizer dilluted in water and sprayed on the leaves is something else and can cause leaves to burn.

I suppose it could be the mineral levels here in our water, but when I worked in the nursery I saw it happen time after time to several different tree species... I should definitely read up on the subject but I have seen it happen, and it is very likely there's something else going on either with the water or the environment here causing the effect through the droplets,

There are a few things I can immediately imagine being the cause, pollution in the air concentrating on a droplet and leaving a concentration of harmful chemicals?

but again Utah is pretty severe in several factors for plants so this might just be a case of seeing a cause and an effect and assuming one knows the answer... I suppose it really couldn't be the sun if it effected our protected maple greenhouse too imma go down a rabbit hole now

 

[zita]

I'm in the UK, we don't get really hot summers compared to the rest of the world

I have had maples completely crisp from too much sun and not enough shade, even in big pots with plenty of water

The same tree is now thriving under shade cloth

I was amazed it even came back in spring tbh, it lost all its leaves and made no effort to bud back last year at all,

I would definitely not recommend putting a tree through that, and for what it's worth the leaves were no stronger when it came out this year! Hence the shade cloth

yeah they came out stronger and thriving now because it collected power last year in the sun.
btw big pots and lots of water isnt the recipe for suntolerance and performance......more like a medium/small pot and very little water until it gets hot and then enough water. Enough means something like 10 in the morning and afternoon again. On crazy days even 3 times.....and also dont forget to water the pot outside to cool it down.
well, i guess i wont convince you best might be you have walk in any nursery around the globe. You would see that the maples do stand in full sun and everything is fine. Some have a greenhouse as well,,,, you will see the maples in there look pale compared to the ones outside.
and last but not least....have you read where Maples have develped?
You can read everywhere that it was OUTSIDE of the forest. Not Inside.
Not into fighting mode at all, just really like to encourage you for max sun for max fun