christmas cactus disease
My christmas cactus has a white powdery something on the leaves. What is causing this?
Monroe County Tennessee powdery mildew
Without seeing the plant, it is hard to say, but it may be powdery mildew, a common kind of fungus. If it is powdery mildew, remove the infected leaves and dispose in the garbage. Make sure the plant has good light and plenty of ventilation (humid, still air are prime conditions to encourage fungi).