I posted on the Daylily Forum on Dave's Garden - Pat is sure it is not powdery mildew - the pattern is not correct and she nor I have ever seen powdery mildew on daylilies. Could it be something that was sprayed on or around the daylilies? Minerals in your water leaving the pattern? If an herbicide, it probably won't kill the daylilies unless it is a strong dose. I have seen daylilies survive Roundup spraying by road crews. Are your daylilies really expiring or are you afraid they might?
