Posted: 28/09/2016 at 12:12
Most usual cause though esp on scabious, asters and the like. There are many possible "causes" for problems of course there are.
I have no doubt that this thread centres around powdery mildew
eliminate the obvious cause as I do. Understand everything you plant, what it needs and will thrive in.
dryish soil here in many areas ...rare for me now to have powdery mildew simply because I have addressed the main cause, viz. susceptible plants in dry soil, by adding plenty of water holding compost at planting time.