White stains on lace maple - not fungus

[akahz]

Greetings.
At some point a few months ago, it seems like it happened within the time frame of a day or maybe two (which makes me wonder if it's sun stained"?)
These white spots appeared.
They did not wipe off like a mildew or fungus. I even tested trying to wipe them off with rubbing alcohol on a few select leaves and nothing happened.
The wilt has started maybe two months ago. There's some healthy ones left but now it's drastically wilted.
I'm trying to be optimistic about the wilt and chalk it up to the messed up climate change we've had here in NE Ohio. A lot of ups and downs and even my apple tree is starting to blossom as are my pussy willows. Not good!

Anyhow. Any ideas? Does vertillium wilt cause such stains?

 

[Paradox]

Looks like powdery mildew to me. I've seen it in the fall when we have a lot of rain.
Good news is the leaves will shed soon, taking it with them

 

[akahz]

Looks like powdery mildew to me. I've seen it in the fall when we have a lot of rain.
Good news is the leaves will shed soon, taking it with them

From what I read, it had to rub off of the leaves. I'll see what others say, but if that is the case, should I still treat the tree, especially going into winter?

 

[Paradox]

From what I read, it had to rub off of the leaves. I'll see what others say, but if that is the case, should I still treat the tree, especially going into winter?

I wouldn't. It will be gone when the leaves fall. I would make sure there were no leaves on it before putting it wherever it is you put it to winter it. Cut them off at the stems holding the leaves to the branch if they are stubborn and don't want to fall off.

Like I said, it looks like powdery mildew but hard to tell for sure from just the picture. I could just be the leaves dying as they do in the fall. Have you had a hard frost yet? This could be frost damage on the leaves as well.

 

[akahz]

No this started in the late summer. Before any of the leaves started to wilt.

 

[BonsaiScrub]

Looks like powdery mildew to me too. My Acer had the same during heavy rain before all the leaves dropped off for winter.

 

[BonsaiScrub]

Looks like powdery mildew to me too. My Acer had the same during heavy rain and low light before all the leaves dropped off for winter.