Wow can you imagine that purple!! That's incredible. Seriously, try adding some baking soda/hydrogen peroxide water when you first see it and spot spray, so, recipe is 1tbs. per gallon baking soda and 2 tbs hydrogen peroxide per gallon, this is what my local dispensary told me years ago. I recommend a little less, my experience folks won't listen, and spray in heat of day when sun is on plant and then they burn it so just in case I say 1tbs. hydrogen peroxide and it has worked just as well, you can go up to this for bigger problems. By the time you take down and I wash, it tastes fine and waay better than powdery mildew... The best thing in my experience is not to let it go, and I prevent it as long as I can with fans, two per plant, cranking all the way through flower stage, this prevents flies and all kinds of moisture issues. Now if you get it and the fan is blowing right on that area, turn fan off and then remove infected leaves and or spot spray, until you manage situation. I went cray cray this year and kinda devastated two of my girls by big leafing tooo much! Then of course I watched nukeheads guy on youtube, randomly came across him and and a two hour video on botany and why you don't big leaf.. I studied horticulture and science long ago, finding my pathology books are a great reference. I think he convinced me not to ever big leaf unless loaded with bugs or mildew etc. Good on ya for doing some experiments. I know you can buy straight potassium bicarbonate powder, which I'm gonna do next year and do some pre preventative spraying in my entire yard..Usually, I use a soap, baking soda, dish soap spray during the entire veg season adding lemongrass, clove, peppermint oil, spray my entire yard trees you name it. Once in flower I just use the baking soda/ hydrogen peroxide and then toward end if I still need it I drop to just the hydrogen peroxide. This post I wanted to mostly show that you can wash pot properly and have it taste that much better.... good luck and good growin! this is my Blue City Diesel, more purple plant than I have ever seen. My budy told me it was a Jager and since I had grown that last 2 years, when it had bright pink hairs, I be like what up...? you ain't no Jager!

@kimmysomelove42 Blue City Diesel