Mould/bugs on tree stock

Morning all
I’ve got this nasty white stuff on my matthiola arborescens (tree stock). Have sprayed it with Roseclear, but doesn’t seem to be working - any ideas??
It’s just about to come into full flower, so didn’t really want to decimate it by removing all the affected leaves and burning them.
But I will if I have to - there’s always next year (we hope!)

Does it rub off?

Is it Downy mildew ? https://www.rhs.org.uk/disease/brassica-downy-mildew

White blister?

Coo - could be either or both!!
It will rub off but takes a bit of effort.

I reckon I’m going to have to cut off the affected leaves and Chuck them
On the bonfire.
Just hope that roseclear will protect the plants and save them getting further infection.

Isn't it milk mixed with water that is good to spray on plants with downy mildew?

I reckon I’m going to have to cut off the affected leaves and Chuck them
On the bonfire.
Just hope that roseclear will protect the plants and save them getting further infection.

We get white blister on the brassicas every year now. Not terribly bad, just annoying. Mostly happens after long periods of rain.