i like your remedy against powdery mildew! SOme plants are definitely more susceptible and I often just take them out of the garden altogether. Certain phlox can get so ratty from the mildew, and also I stopped growing zinnias cuz of the mildew. But I LOVE zinnias! Such perky cut flowers.
Yes, those 2 also have issues, but the raw milk solution worked really well on them. Stopped the mildew dead on the phlox. It also kept the rust on the hollyhocks in check all season.