I've several rex begonia types - most of which are suffering from a form of mildew. This also affected my angel wing begonia. I wonder if this is the sort of thing to expect of begonias during this time of the year. If so what should I have been doing to prevent this from recurring. I'm planning to treat these plants with some anti fungal sprays but still I would rather prevent this from happening next year. I'm told that the form I have is due to dry indoor air.

I need advise from the seasoned indoor gardeners.