Black/Dying leaves

[iliketrees]

Had a lot of the new growth on my JM die. Attached pics below. Any ideas what it might be/treatment?

In PA

 

[Bonsai Nut]

Looks like sun/heat damage to me. JM are prone to wilting in young growth - particularly if you have pruned or partially defoliated the tree and don't give it sun protection until the leaves have callused up/hardened.

 

[iliketrees]

Looks like sun/heat damage to me. JM are prone to wilting in young growth - particularly if you have pruned or partially defoliated the tree and don't give it sun protection until the leaves have callused up/hardened.

Thanks for your response! Though, my tree really only gets sun from morning to 12 and is in pretty heavy shade for the entire afternoon. Maybe it's still possible.

 

[Bonsai Nut]

We just hit our first week of temps in the high 80's... and I got some wilting on some of my JM that are in total shade from noon on.

 

[iliketrees]

We just hit our first week of temps in the high 80's... and I got some wilting on some of my JM that are in total shade from noon on.

That's good to know! was concerned it might be some fungal thing or something. Appreciate your response.

 

[Adamski77]

I would just put it in the shade... I have trident maple that is getting burnt here in Shanghai all the time. I was quite reluctant to put it in full shade till recently... but finally tree landed in full shade... getting maybe one hour of the sun just before sun set. And new leaves coming out seems (so far) to be doing much better than previous flushes of growth. Admittedly it's not Japanese Maple... but would be my first step...

 

[iliketrees]

I would just put it in the shade... I have trident maple that is getting burnt here in Shanghai all the time. I was quite reluctant to put it in full shade till recently... but finally tree landed in full shade... getting maybe one hour of the sun just before sun set. And new leaves coming out seems (so far) to be doing much better than previous flushes of growth. Admittedly it's not Japanese Maple... but would be my first step...

Thanks for your response! Will definitely consider getting it into the shade more especially as it gets warmer here.

 

[boonefrog]

Is it possible you over-fertilized? When my JM leaves looked like that, I was told that might be the issue.

 

[zita]

to me that tree looks perfectly fine and natural, wouldnt change anything at all

 

[EAlbertse]

Not saying this is what your JM have but I have had similar symptoms on my Chinese maples and Japanese maples in the past. In my situation the meristematic tissue and just unfolding leaves would die and turn black just at the growth tip. I also had the leaf shape become disformed of the younger surviving leaves at the growth tips. Originally I though my plants had anthracnose's and I applied fungicides without any effect. It was very frustrating because the dieback causes branch extension termination. Eventually I got hold of a handheld microscope (a good magnifying glass would work too) and I noticed I had mites crawling all over the growth tips and tissue. After doing some more research, I narrowed the symptoms down to a broad mite infestation. Maybe check your JM with a magnifying glass and see if you can see little mites move. Before resorting to pesticides it is always important to first identify the pest and problem and then decide on an appropriate course of action.

 

[zita]

well, to go over the plant with an insecticide is standart for me about end of may even if i cant see anything crawling around.
The maples love it.

Black does always mean too wet regardless sunshine and brown colors are sun caused while related to your wateringmanagement.

that said, it is normal for the the leaves to wear out, they have a lifespan. The more they have to work or suboptimal conditions, the faster they will need to be replaced.

 

[EAlbertse]

Always remember insecticides are pest specific. For example, systemic imidacloprid increases fecundity of some mite species and can actually increase the pest problem. Also it kills the natural mite predators making it worse.

 

[zita]

good point, i do not understand much about it.

The one i use is for aphids. It is a propper insecticide that vapors and kills even the hidden ones. They come every year, not on all maples, on some more, some less. i always treat the whole collection.
My impression is, that the maples love it.

 

[NMbonsai]

I agree with @Bonsai Nut that it is most likely heat damage. I have the same issue here in the desert southwest with my JM. They put out a beautiful spring flush and, as soon as the temps start staying in the low eighties and above, the edges of the leaves start drying out, but usually remain on the tree into the summer. In the spring they get about 6 hours of morning sun a day, but I move them into 50% shade in early June. The other weather effect experienced here is the drying summer wind that usually comes up in the early afternoon and last into the evening.
As mentioned above, mites could be the issue. Another way to to check for them is to hold a piece of white paper under the affected branch and tap or shake it. If you see tiny moving dots, smaller than a period, then spider mites are the problem. It is always better to check first before apply an insecticide.

 

[iliketrees]

Is it possible you over-fertilized? When my JM leaves looked like that, I was told that might be the issue.

I don't think so. It's the usual amount of fertilizer I have used successfully in the past on similar trees plus its organic which (to my understanding) is generally less harsh than some other fertilizer options.

 

[iliketrees]

Not saying this is what your JM have but I have had similar symptoms on my Chinese maples and Japanese maples in the past. In my situation the meristematic tissue and just unfolding leaves would die and turn black just at the growth tip. I also had the leaf shape become disformed of the younger surviving leaves at the growth tips. Originally I though my plants had anthracnose's and I applied fungicides without any effect. It was very frustrating because the dieback causes branch extension termination. Eventually I got hold of a handheld microscope (a good magnifying glass would work too) and I noticed I had mites crawling all over the growth tips and tissue. After doing some more research, I narrowed the symptoms down to a broad mite infestation. Maybe check your JM with a magnifying glass and see if you can see little mites move. Before resorting to pesticides it is always important to first identify the pest and problem and then decide on an appropriate course of action.

Thanks! I'll check it out with a magnifying glass!

 

[iliketrees]

I agree with @Bonsai Nut that it is most likely heat damage. I have the same issue here in the desert southwest with my JM. They put out a beautiful spring flush and, as soon as the temps start staying in the low eighties and above, the edges of the leaves start drying out, but usually remain on the tree into the summer. In the spring they get about 6 hours of morning sun a day, but I move them into 50% shade in early June. The other weather effect experienced here is the drying summer wind that usually comes up in the early afternoon and last into the evening.
As mentioned above, mites could be the issue. Another way to to check for them is to hold a piece of white paper under the affected branch and tap or shake it. If you see tiny moving dots, smaller than a period, then spider mites are the problem. It is always better to check first before apply an insecticide.

I noticed some webs earlier in the season and did this paper test and didnt see anything. I also havent really seen any webbing since so I just chalked it up to a spider. I'll check again though thanks for your response!