I'm really starting to "get into" asters...I've got several native varieties on the property. The dark purple is a tall bushy plant, very prolific flowers and a gorgeous color. Then I've got the white "michaelmas daisy" type. I've got a lovely pale lilac colored one with heartshaped leaves and then another sort of mixed lilac/white type with narrow leaves. since these are all natives (and native to my property), they all seem to be doing great...it's only the purple one in the driest spot that turned crispy brown, so with all the feedback I've received here....I'm really starting to think it's some sort of fungus/mildew that is brought on by water stress.
