Spotty Japanese maples - please help!

5 years ago

last modified: 5 years ago

Hello all, last year a few of my young potted japanese maples got some sort of fungal infection (I think) that produces pale spots on the leaves. They don’t rub off and are visible on both sides of the leaf. It was at the end of the season, so I was advised to clean up all the fallen leaves and that the trees would probably be fine next year.

Until this week, all was fine, but then I saw one spot, and the next day dozens of them. It spreads so quickly and the potted trees are at different ends of the garden. Also two young maples in the ground have it.

I‘ve done a lot of research but could only find info on a spot that turns black later on, which this one does not. It may just be cosmetic, but it’s only April so the trees will be diseased for rest of the year :-( Actually I think the leaves started to dry up and fall early last year.

Do any of you know what it might be?

Or can anyone recommend a fungicide that is safe to use on JMs? I’d like to spray the few that have not yet caught it, or treat them with a soil drench. I enclose some photos. Please help! Thank you.

Featured Answer

gardengal48 (PNW Z8/9)

5 years ago

At this early stage of the season, it could very well be. But it is almost entirely cosmetic in nature and no treatment is required or even recommended. In fact, spraying just about anything other than water on a JM wll cause a phytotoxic reaction that is usually worse than the problem one was trying to solve.

Later in the season, and especially with containerized JM's, you will often see similar spotting and that is typically due to uneven watering practices.

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Comments (6)

sabine_farm
Original Author
5 years ago
A bit more research has led me to believe it is phyllosticta leaf spot....
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ken_adrian Adrian MI cold Z5
5 years ago
In fact, spraying just about anything other than water on a JM wll cause a phytotoxic reaction

==>>>

i see a pretty nice lawn there.. was it sprayed?? .. was the tree leafed out at the time??? .. can you rule out drift of said spray .... ????

i agree .. leaf damage .. on deciduous trees.. never really bothers me.. spotted or not.. they continue to do their job converting sunshine in energy ...

and i usually fear.. i will just do further damage slathering on more goos .... [ i hope you understand those very technical terms... ]

ken
sabine_farm thanked ken_adrian Adrian MI cold Z5
sabine_farm
Original Author
5 years ago
Thank you Ken! I’m embarrassed to say the grass there is fake! It’s by a pool, within a fenced in area, so we thought it would be ideal not to have to mow the lawn and get grass cuttings in the pool. That’s my excuse and I’m sticking to it!

There’s been no overspray of anything. We have had a lot of wet weather and have had some fungal issues with other trees and plants. Our poor photinia is spotty too, but a different type of spot - quite common amongst red tipped photinia trees.

Some of the top leaves on the affected maples are going a bit crispy, which I remember them doing last year. I wonder if the leaves do fall early, whether the trees could have a second flush of leaves this summer.

Thank you gardengal for your advice - I shall resist spraying them with anything and see how they do. Have a great weekend!
gardengal48 (PNW Z8/9)
5 years ago
" I wonder if the leaves do fall early, whether the trees could have a second flush of leaves this summer."

Yes, they will :-) And you won't have to wait long. Although I grow most of my JM's in containers and have for many years, every now and again, something may get overlooked and the leaved can dry, shrivel and drop off. If you tend to them attentively and water as necessary, they wlll produce a new flush of foliage almost immediately. I've had at least one tree completely lose its leaves in mdiseaon and leaf out again.
sabine_farm thanked gardengal48 (PNW Z8/9)
sabine_farm
Original Author
5 years ago
That is good to know Gardengal - thank you!