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Black spots on acer leaves (shishigashira)
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Author:  mikemike [ 01 Sep 2016, 15:20 ]
Post subject:  Black spots on acer leaves (shishigashira)
Hi there

Long time lurker, first time poster :).

I bought a lovely shishi gashira maple at Greenwoods last week. It was in absolutely tip top condition when I got it. Now a week later the leaves are developing small black spots that seem to be spreading. I have a few other acers in the garden and none of them are affected. I live in Manchester which isn't renowned for its great weather but the previous week hasn't been too bad, the tree has had enough water.

I have a few questions and wondered if anyone here might have any insight.

1. Anyone know what this could be? My immediate thought was some sort of air borne fungal thing local to where I live.
2. What should my immediate course of action be?
3. Is this purely cosmetic or could it damage the long term health of the tree?
4. How can I prevent it happening again in the future?

Pictures below, hopefully someone can shine a light on this for me.

Thanks, Michael.

Image

Image

Image
Author:  geoff m5eay [ 01 Sep 2016, 20:26 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
Why don't you talk to Corin?
Author:  corin [ 01 Sep 2016, 21:04 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
hello Michael

You are right, it didn't have them on before

have you watered it on the sun, and its got sun burnt through water droplets?

leaves will naturally be breaking down soon, some trees are doing this early this year, i know some that have lost leaves already

buy you don't usually get spots like that

I wouldn't worry,as leaves will be off soon anyway

i dont leaf cut shishi, so they are spring 2016 leaves
Author:  mikemike [ 01 Sep 2016, 21:17 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
Ah

Hi Corin, now you say it yes I think it could be sunburn through water droplets. We have had some rare hot sunny days and I did water one of those mornings. I hadn't considered something that simple... User error!

As I said it was flawless when I got it, only took me a week to muck it up :/

Thanks for the info and I'll defo be back to Greenwoods soon as I'm allowed :)
Author:  Will [ 01 Sep 2016, 21:19 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
My Shishigashira has started to drop leaves already before even changing colour for the second year running I bought this for the "fantastic Autumn colour" but it just drops them
Author:  corin [ 01 Sep 2016, 21:44 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
patience Will San
Author:  Will [ 01 Sep 2016, 21:54 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
corin wrote:
patience Will San



:think: :203pokey: :07hysterical: :32crazy:
Author:  Drew [ 02 Sep 2016, 09:20 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
When I water my maples i try not to get the leaves wet to avoid any potential issues suggested above.
Author:  PeterBone [ 02 Sep 2016, 11:41 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
The issue of the sun causing burning through water droplets is a myth. Water droplets can act as a lens, but the focal point will be well behind the leaf, not on it.

http://www.telegraph.co.uk/news/science ... unked.html

The damage above looks like tar spot to me and is not a serious problem.
Author:  Gary Jones [ 02 Sep 2016, 11:48 ]
Post subject:  Re: Black spots on acer leaves (shishigashira)
Saw this on wikipedia. Might help for next year. Basically you should remove and destroy this years leaves when they fall.

Quote:
Disease control
Tar spot is a localized disease that causes mostly cosmetic symptoms and is therefore not a highly controlled disease.[3] One of the best ways to manage the pathogen is through proper sanitation techniques.[3] Because the fungus overwinters in diseased leaf debris, removing the debris in fall can help reduce the occurrence of the disease.[3] In certain severe cases, fungicides can be implemented to help with control.[7][12] Copper fungicides sprayed in early spring when leaves are budding and twice more throughout the season to help reduce the disease. However, chemical control is not normally used because this disease is mostly cosmetic. Resistant varieties are unknown. Also, because the affected tree species are of low economic value, yield reduction is of little concern to growers. By far the most important practice is to keep a clean yard and remove as much debris as possible.[3][5]
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