No visible insects, one plant lost and another at risk. Doesn't seem like powdery mildew. Haven't seen it before.
Odd White Markings on Plant Leaves
Certified GKH Gardening Expert
This looks like it may be a case of Downy Mildew.
Thanks so much! These are (were) house plants. How on earth did this happen? I've had them for 6 years, vigorous bloomers, lovely strong plants. We did move in May... could the house somehow be the problem? Lots of fresh country air and open windows. Cause??