Powdery mildew appears as a dusty white to gray coating over leaf surfaces or other plant parts. In most cases this fungal growth can be partially removed by rubbing the leaves. It might be identified incorrectly as dust that has accumulated on the leaves. Powdery mildew, however, will begin as discrete, usually circular, powdery white spots. As these spots expand they will coalesce, producing a continuous matt of mildew (similar to dirt or dust).
For indoor plants, disease management includes gathering up and destroying fallen leaves, reducing relative humidity around plants, and spraying with a fungicide. Some products that may be used to treat powdery mildew on indoor plants include: potassium bicarbonate (Greencure), Bacillus subtilis (Serenade Garden RTU* or Plant Guardian Biofungicide), and some products containing the active ingredient neem oil.
A very good friend gave me 6 beautiful clones to raise. It's my very first attempt at indoor growing. We have 6 little lovelies under a high output 250w fluorescent on a 12/12 cycle for 4 weeks now with 4 to go. All of a sudden, my bubble gum has developed a dry, white mold(?) Does anyone know what it is and how to stop it? 
