Houseplants that grow in environments with cool temperatures, inadequate air circulation and indirect sunlight may develop an unsightly fungal infection. Powdery mildew covers plant foliage with a white powder, often starting small and growing until it covers the leaves. Left untreated, powdery mildew can spread from plant to plant. Get the white stuff off houseplants and minimize damage to your plants by treating the powdery mildew before it damages your plants.
Move houseplants showing signs of powdery mildew to locations with more sunlight and air circulation and keep them away from other plants, if possible. While this will not reverse the powdery mildew, it should help minimize the spread of the fungal infection.
Clip all foliage with white mildew off the plant with the pruning shears. Make sure you remove every piece of foliage with powdery mildew with the pruning shears. Discard the foliage into the garbage immediately.
Wash your hands with antibacterial hand soap after handling the infected plant. Saturate a paper towel with isopropyl alcohol and use the paper towel to clean the blades of the pruning shears thoroughly. These precautions will minimize the possibility of spreading the powdery mildew between your infected and uninfected plants.
Spray the fungicide spray lightly, but thoroughly, over the remaining foliage and stems of the infected plant. Spray infected plants once per week with the fungicide spray to control the spread of the fungal infection.