i never spray anything on plants with lights on found a good article for u but u can goggle powdery mildew on cannabis and u will get lots of results
but here is what ed rosenthall says
CANNABIS CULTURE - Ganja Guru Ed Rosenthal helps you remove powdery mildew from your plants!
Suffering from powdery mildew? Thats that white, powdery growth on top of the leavesit almost looks like flourit can kill your plants. Here is the simplest way of getting rid of it:
- Go to your local garden shop, or nursery, and buy a bottle of potassium bicarbonate
- Mix an ounce of potassium bicarbonate in a gallon of water and 1.5 cups (12 oz, 340 grams) of milkI prefer non fat, because it is less oilybut whole milk works as well.
- Spray on your plants or dip them in it. It kills the living fungus and the potassium bicarbonate creates an alkaline environment that hinders germination of spores.
when do i do the milk light on or off?