Hi folks, I just thought I'd share my experience with this fungal disease and hopefully someone who needs the info can use it. I discovered PM on my plants around day 10 into flower. I caught it early and decided to wage an all out assault on it before it got out of control. After some research I decided on a combination of copper fungicide first, one time only, then alternating with a mix of "dr earth" brand garden fungicide, which has some essential oils and bicarbonate. I also add about 15 drops each of thyme oil and tea tree oil per liter with a few drops of yucca extract as an emulsifier and wetting agent, and a tiny pinch (15-20 ppm) of potassium silicate. I usually spray them every 3 or 4 days when I when I start to see the reappearance of PM, before lights off. I turn my lights off a half hour early on those days and put a dehumidifier in the room and leave all the circ fans running so that the plants will be dry before lights on . In conjunction once a week or so I give them a chitosan lactate foliar at around 200 ppm. I also feed them 40 ppm potassium silicate with every other watering in coco. All of these strategies seem to be working quite well, the PM reappears and grows much more slowly now, I think the chitosan and the silicate especially have helped a lot with making the plants more resistant, the store bought spray by itself seemed to only work for 3 days before the PM was back, now it takes more like 5 or 6 days before I see a few little spots and they are very small and slow growing, I'm just into week 4 now and my plants already have quite massive buds and lots of trichomes, which could be a side benefit of the chitosan. There were no trichomes at all in week 2 when I started using it and within a week of the first time I gave them the chitosan they were covered in sugar. Anyway here's a pic of one of my plants, the strain is corn bread from rare dankness seeds. According to the supplier chitosan lactate is supposedly better at controlling mildew than chitosan oligosaccharide, although both are fungicidal, antibacterial, and antiviral, as well as inducing SAR in the plants which makes them more resistant to disease and pests, as well as increasing resin production, at least in trees, although I have not been able to find any scientific studies on increased resin production in cannabis through the use of chitosan, but that's not really why I'm using it anyway, if that's a side effect though I'm all for it. I think I will probably stop the chitosan after the next spray, it's non toxic but I'm not really into smoking it either. Beats smoking PM by a long shot though... I hope this info is useful, Happy gardening