Hi, I wondered if anyone can identify the white powdery substance that has appeared on a couple of my plants (photo of affected Monarda fistulosa plant attached). Seems to mainly affect the edge of the leaves but also some of the stems of the plant. The exact same has appeared on Digitalis grandiflora. All affected plants are in pots and have very recently been potted on. I have more of each type of plant that haven't been potted on that look fine. I used scissors to cut back last seasons growth on both types and wasn't very careful with cleaning them which may explain the spread.
Thanks very much for any thoughts anyone has.
Andy
