Burned Leaf Tips

CubanBonsai

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One of my Japanese Maples have small burned leaf tips. They are pre-bonsai trees, and I keep them in a clay pot on a balcony facing east. Here in northeast Ohio it rains at least once a week, temperatures in the day can go up to the 90s and at night it may drop to 65. (USDA Hardiness Zone 5a)

Some "experts" online point to the fact that this problem is very common and almost characteristic of Japanese Red Maple, while others say it is too much sun and wind...

Are burned leaf tips a common issue for Japanese Red maples? If not, what can I do to help my small trees.

Thank you
 

Paradox

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Yes it is common and it is caused by strong afternoon sun and heat in the summer. The best way to deal with it is to provide shade during the highest heat/strongest sun in the afternoon.
 

MACH5

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Yes it is unfortunately VERY common particularly when growing in such small containers. As Paradox has mentioned, keep it in bright shade during summer and well watered. Even with all precautions taken it is difficult not to get at least some leaves with burned tips.

In my experience, the susceptibility to leaf burn even varies from tree to tree. Just remember that A. Palmatum's are understory trees. They thrive in filtered light areas.

Although it appears that I had no leaf burn in the forest below, I had cut some leaves off that were sun damaged before I took this picture. I find it quite challenging to bring a Japanese maple with leaves in perfect to near perfect condition all the way into autumn. Then again everything in bonsai is a challenge :rolleyes:

 

CubanBonsai

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Yes it is common and it is caused by strong afternoon sun and heat in the summer. The best way to deal with it is to provide shade during the highest heat/strongest sun in the afternoon.

What about root rot? - Thank you
 

MACH5

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It may be helpful if you can post a pic of your tree. Is difficult to diagnose without a visual. If you suspect root rot, the general symptoms would be an overall lack of vigor, yellowing and or wilting leaves, etc. The tree will look sickly.
 

jk_lewis

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What about root rot? - Thank you

What about it? Does it cause burned leaf tips? With some Japanese maples, I'm sure the answer is probably, possibly, or yes.

But heat and sun is the biggest cause.

Still, you say these are pre-bonsai, so it doesn't really matter. It's cosmetic at worst and usually can be "cured" by just removing the offending leaves.
 

GrimLore

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Do yourself a favor and get them out of the full morning sun during the hot spell you are having. They will do better in shade during that time. Also during the hot weeks do not fertilize as the tress are stressed.

Grimmy
 

CubanBonsai

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Here are the photographs. As you can see the plants have only 2-3 sets of leaves, so I can't really remove some of them. Thank you.
 

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Paradox

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What about root rot? - Thank you

As previously mentioned, root rot will have different symptoms than burned leaves.

Keeping your tree in shade will not cause root rot. Keeping your tree in soil that does not drain and retains too much water and/or overwatering will cause root rot.
 
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Dav4

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Here are the photographs. As you can see the plants have only 2-3 sets of leaves, so I can't really remove some of them. Thank you.
Those appear to be a bit over potted. Over potted trees tend to have roots that stay wet, so you need to watch the watering closely.
 

Poink88

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From what I was told...it is neither heat nor sun that is the culprit. It is lack of water going to the tree/leaves.

Granted, heat and sun help dry the soil faster...it is not the real problem. I have a trident (not sure how it compares to Japanese Maple) in full TEXAS sun and it doesn't have any burned tips. I also have several in shade that is not maintained water-wise as perfectly and they have burned leaves. :D

Drying can kill roots as well as over watering...and these two usually results from the bonsaists over reaction from one or the other...a vicious cycle that again may lead to less (or no) water going to the tree/leaves.

I tend to agree to this theory.

That said, I agree that giving it shade and controlling the heat/sun (as well as wind) will help widen your window to maintain proper soil moisture levels especially on plants in small bonsai pots.

Factors affecting it; heat, wind, foliage amount, pot size, soil mix, watering frequency, etc.
 

tmpgh

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Dario, I've been having a similar problem with my JM for the past two seasons and I can say for sure in my case it is not a water issue. My soil is well maintained. I believe it is sun damage in MY case.
 

Dav4

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Dario, I've been having a similar problem with my JM for the past two seasons and I can say for sure in my case it is not a water issue. My soil is well maintained. I believe it is sun damage in MY case.

Leaf burn occurs because the leaf's demand for water lost through transpiration exceeds the capacity of the roots to provide it...the underlying cause for this will vary, as mentioned above.
 

MACH5

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From what I was told...it is neither heat nor sun that is the culprit. It is lack of water going to the tree/leaves.

Granted, heat and sun help dry the soil faster...it is not the real problem. I have a trident (not sure how it compares to Japanese Maple) in full TEXAS sun and it doesn't have any burned tips. I also have several in shade that is not maintained water-wise as perfectly and they have burned leaves. :D

Drying can kill roots as well as over watering...and these two usually results from the bonsaists over reaction from one or the other...a vicious cycle that again may lead to less (or no) water going to the tree/leaves.

I tend to agree to this theory.

That said, I agree that giving it shade and controlling the heat/sun (as well as wind) will help widen your window to maintain proper soil moisture levels especially on plants in small bonsai pots.

Factors affecting it; heat, wind, foliage amount, pot size, soil mix, watering frequency, etc.




Dario they cannot be compared. Tridents are way more resistant to heat/sun than Japanese maples which are more delicate in this respect.
 

xray360

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I had the same problem last year. Almost all the leafs were burnt on my maples. A book said not to get the leafs wet when you water. After following this they are much better. My deck gets up to 90+ degrees some days too. Try to avoid getting them wet during sunny days.
 

63pmp

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Dario said;

From what I was told...it is neither heat nor sun that is the culprit. It is lack of water going to the tree/leaves.

I tend to agree to this theory.



If this is the case, why don't the leaves and young stems wilt? You never see wilt with marginal leaf burn, and you can have wilted tips recover after watering and not have burning.

Paul
 

Eric Group

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First- those are perfectly healthy young trees pictured by the OP. Assuming they have been growing steadily I wouldn't do ANYTHING to them. That at is a barely noticeable leaf burn and not an indication of any trouble whatsoever.

Second, I have had extensive experience with leaf burn on maples. Been caring for them for 10-15 years or so, and I have seen mild leaf damage all the way up to tree death due to varying stress factors and in my experiences WIND is a much bigger culprit for leaf damage, especially when paired with hot temps and not enough water... Which is what wind does- dries out the SOIL, not the leaves. Wind (and heat) will dry out the soil which will crisp up a delicate JM leaf faster than anything... Sun alone won't do any damage if the tree is properly acclimated to the environment you have it in and as long as it is kept sufficiently watered. I have a couple Japanese Maples in FULL SUN, and this is SC- we get up to and above 100 degree heat in the summer and already had multiple days in the upper 90s- 100+ this year- and neither the trees in the ground growing out, the seedlings nor the ones in Bonsai pots/ bonsai soil have leaf burn. I am happy to stay we have had some wind and I haven't seen any issues from that either, but again the main determining factor for those dreaded crispy tips seems to be how much moisture is in the soil, not the environment or weather- as long as you can keep that soil right your tree should stay pretty happy. If it is root bound, recently repotted and trying to support too many leaves from too few roots.... Or anything comparable (like maybe root rot, though that is probably going to lead to damage that will extend well beyond leaf burn as Mach said)- you are way more likely to see the burned leaves.

About root rot though... I have never had much issue with it over the years, especially with Maples. They like the soil a little wet/ moist... Some species can actually grow with roots completely submerged in water (Rubrum and Amur for instance) and I recommend erring on the side of being TOO wet if you are not sure what the proper balance is yet. Obviously JM is not the same tree as Acer Rubrum, just saying Maples can handle a lot of water and if your soil is pretty well draining it should be almost impossible to over water a Maple to the point of causing the roots serious harm.

One more note- you can see some spots appear from the use of harsh chemicals on your tree. If spraying with a harsh insecticide or fungicide, do it in the dormant period if possible. Also, insecticidal soaps are able to cause little burn spots if applied in full sun...

Speaking to the idea mentioned above that simply watering a tree- any tree I have ever worked with- in full sun and getting some on the leaves will cause burn spots is a complete MYTH in my opinion. I know it has been perpetuated for decades by all sorts of people... But I water in full sun all the time and I have never been able to attribute any leaf burn to it whatsoever. If your tree is dry, WATER IT! They can absorb some water and nutrients through the leaves, so go ahead and water from the top down! If this idea was true, you would not have a tree in your collection survive the Summer wiout leaf burn! How often does rain fall on them while the sun is shinning or when the sun pops out of the clouds almost immediately after the rain while the leaves are still wet? It happens ALL THE TIME in my yard.. The idea is that leaf droplets cause a magnifying effect because of their concave shape and the sun shinning through them burns a spot into the leaf. Just not true- the water itself would keep the leaf's surface cool... Unless you believe sun shinning on a leaf causes the water droplet to BOIL and burn the leaf? It doesn't... The water is evaporated or sucked up by the tree prior to anything nearly so dramatic occurring...
And while I understand the idea's origination and why people believe it... I just don't have it happen to my trees. Maybe mine are all super trees with mutated leaf burn resting powers? Doubtful... More likely it has been other things causing little brown spots on people's leaves and they attributed it to the water droplets...

I struggle more with deformed leaves during the hotter months than leaf burn, but that is a discussion for another thread, and it was in fact actually already discussed in a thread here recently.
 

iant

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Side note:
If I had (and I do) little seedlings that small I'd put a little wire on 'em and get a little movement in the trunk while you still can!
Ian
 

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CubanBonsai

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Those appear to be a bit over potted. Over potted trees tend to have roots that stay wet, so you need to watch the watering closely.

I believe that overwatering was the issue as I have another pot with a Red Japanese Maple located nearby (same sun exposure), but it did not receive so much water rain. Of course, the leaves are ok on this pot.

Thank you.
 

CubanBonsai

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Side note:
If I had (and I do) little seedlings that small I'd put a little wire on 'em and get a little movement in the trunk while you still can!
Ian

Wow that is very nice... I guess I had not considered the level of flexibility. I was always told to wait a year (from seedling) to start straining the tree.

Thank you.
 
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