ok, to any of you who deal with powdery mildew, let me lend you some advice on how to effectively treat the fungus in an organic manner..... with water! This is for when you are past the point of being able to treat with any other organic method of spray, which is after week 2.5-3 of flower. if your treatments don't do the trick all the way through flower, do not fear.
step one, remove infected plant(s) from the room.
step two, give your plant a shower with distilled water from some kind of sprayer; this is to give a little water pressure but not blasting the plant. shower in order from head to toe, to wash away the spores off of the leaf surfaces. and really
a couple things to note about powdery mildew: one is that it is an airborne spore and does not grow hyphae in the soil. so the best method of treatment is to wash the spores away. water prevents the vast majority of them from becoming airborne. Another is that powdery mildew thrives in a dry environment, this allows the spores to become airborne much easier and let me tell you, humidity has got nothing to do with it. i'm talking dry leaf surfaces where they can land in low wind zones, develop, and start feeding from the plant.
you can repeat this treatment with no worries!!!!!!!!! if you see some more mildew try and develop, just give them another shower. when you stop the production of spores, which might take some because of spores in the room, you will end the life cycle of the fungus. i'm also treating the air with ozone at night to kill spores in the air. just a 10 min blast with circulating fans running and then i turn the exhaust back on.
maybe i'm arriving late to the party with this info, but nowhere did i see anyone mention doing this. this was my own desperation to try and save these plants to get them to a mature harvest. i was getting worried for my black domina, but i no longer fear a mildew take over. i'll just give them a shower. they are extremely happy with me right now lol. i wish i would have thought of this for the cheese plants!!