Help powdery mildew on my Scabiosa

[Sl0wM0]

I bought an organic spray and not sure it’s doing much.

Mix 40% milk and 60% water and spray that on.

How often?

We have knautia macedonica which this year has had awful mildew. I cut each one to the ground and it is sending up nice green shoots again. I think knautia and scabiosa are the same plant?
Mildew is due to being dry so maybe cut off some of the worst mildew and give it a soak, but if you look right at the base of the plant you may already see new shoots ready to grow. They are prone to this I believe which is a shame as they are lovely plants and the bees love them.

Apparently making a 'compost tea' with chives works well for powdery mildew. I've not tried it myself but just came upon the suggestion on YouTube.