Affected leaves should be removed from the plant immediately. Clear bigger fan leaves, and trim in high-density, bushy areas.
If indoors, install a dehumidifier and set it to correct humidity levels for the plant's life stage. Keeping temperatures above 80*F will also help kill off White Powdery Mildew.
Homemade Sprays:
Before using any sprays indoors, turn off all fans.
• Potassium bicarbonate: 1 teaspoon per gallon of water.
• Milk: 1 part milk to 3 or 4 parts water.
• H2O2: 1 part 3% H2O2 to 3 parts water.
• Baking soda: 1 teaspoon per gallon of water.
Fungicides:
• Docton Zymes Eliminator
• Sulphur based fungicides
Do not spray on buds; sprays are usually not safe to consume.
Plant washes like Lost Cost should also clear powdery mildew from the leaves.
If powdery mildew is found on buds upon harvest, we really don't recommend consuming it, but if you must, be sure to wash your buds first.