water and ph up tp 10.0 and spray plants mildew cure,serenade,neem,h202 and water,after harvest h202 dip like george cervantes it works 100% it will kill the powdery mildew but once u have it in a strain its systematic (internal) just waiting for any reason to come out .i have seen powdery mildew in 35% humidity and 75* temp it depends on strain i wont grow anything that gets powdery mildew any more