Pale spots on oak salpling leaves - what is this and how do I treat?

[ForeverRaynning]

Just went to check on my plants and moticed my oak sapling/seedling looking like this.



We did have a small fire burning the other day when family was visiting but unsure how smoke damage looks. I know powderly mildew is a thing, could this be it? We don’t really get spider motes outdoors here in the UK as far as I know but I can do the paper test if thats a possible cause (EDIT - spider mite paper test was negative, not a single speck!).

Whats the best course of action in terms of diagnosis and treating?

Thanks In Advance!

 

[Mike Corazzi]

At FIRST BUD BREAK start spraying copper!!!

That won't happen then.



Mildew LOVES oak.

 

[ForeverRaynning]

At FIRST BUD BREAK start spraying copper!!!

That won't happen then.

View attachment 561467

Mildew LOVES oak.

Copper can only be used to treat deficiency here in the UK so not sure if I can even get my hands on any to spray. Also read once its in the live tissue copper doesn’t touch it, do you know if it can be treated once its taken hold or is it too late?

 

[ForeverRaynning]

I’ve neem sprayed the heck out of it (soul covered so it doesnt go in the soil), and lightly misted the rest of the plants just to be safe. Bit of a hail mary really, I know humidity makes it worse but we’ll see what happens. Its NW England, all we really get is humid overcast days, had a bit of a heatwave last week though. I don’t have any decent plants yet, so theres no major losses to be had. But did recently discover I really like oak trees so was looking forward to this ones development.

 

[Wires_Guy_wires]

Neem doesn't prevent or kill mildew.
Hydrogen peroxide diluted to 1% in tap water will kill most varieties of mildew after two treatments. It can sometimes leave brownish spots where the fungus died though.

Copper sulphate should be easily available at arts and crafts stores. Sometimes it's sold as vitriol.
But to my knowledge it's also used some times in veterinary care as an antifungal spray.
Another product I have seen mentioned as a preventative is potassium silicate. But I never got it to work.

Keep in mind though, that this is an easthetic problem. While mildew does cover the foliage, it hardly blocks any sunlight, no more than the loss of three to six leaves would. Which is marginal.
My oaks get it regardless of watering, sunlight, wind or whatever. It seems that it's particularly attracted to the cuticle wax in oaks specifically.

 

[ForeverRaynning]

Neem doesn't prevent or kill mildew.
Hydrogen peroxide diluted to 1% in tap water will kill most varieties of mildew after two treatments. It can sometimes leave brownish spots where the fungus died though.

Copper sulphate should be easily available at arts and crafts stores. Sometimes it's sold as vitriol.
But to my knowledge it's also used some times in veterinary care as an antifungal spray.
Another product I have seen mentioned as a preventative is potassium silicate. But I never got it to work.

Keep in mind though, that this is an easthetic problem. While mildew does cover the foliage, it hardly blocks any sunlight, no more than the loss of three to six leaves would. Which is marginal.
My oaks get it regardless of watering, sunlight, wind or whatever. It seems that it's particularly attracted to the cuticle wax in oaks specifically.

Right, I turns out I can get liquid copper fungicide on amazon, so thats good to know (also the sulphate crystals). Read about people using hydrogen peroxide to sort it as well. By two treatments, how far apart would these be? I assume peroxide is best to kill it and the copper is just as a preventative? How often would the preventative be needed? (I’m still pretty new to all this)

Ah, so it’s not a death sentence or anything then, good to know. I’ve read it stunts growth and can lead to death eventually, had to remove two leaves that had shrivelled on it so ideally want it gone even if it is just for the year or even a few months or weeks, once I know how to clear it properly it’ll be easier to manage.

 

[Wires_Guy_wires]

The two treatments can be a day apart. Since you just want to knock it out and peroxide does little harm to plants.
Preventative copper sulphate in my care is done twice: once when the leaves start to leaf out, the second one a month later. You could treat more often if you'd want but I would cap it to a maximum of 4 times to prevent metal poisoning and to keep the microbiome from collapsing.