I have been flowering for three weeks and small bu...

Hi @CommanderCannabis! If you're talking about the sugar leaves onto/close to bud-sites, I won't touch them until harvest, you may harm the buds and they're useful to the photosynthesis process. If you're talking about the old fan leaves on the main stem, then go ahead, especially if these are creating shades on lower bud-sites or if you think the airflow inside the plant is not sufficient. In order not to shock the plant, do it slightly, and only remove 3~4 leaves at a time, then see how it goes after a day or two. Now about your powdery mildew issue, it's too late to spray anything, but you can treat with the organic product of your choice (milk, neem oil, garlic, vinegar) using a sponge, apply delicately on the leaves and make sure you don't touch the bud-sites with the sponge. Hope this will help, keep us up-to-date and happy growing 👊

Hello ! After 3 weeks I would not defoliate anymore as the plant will not make new leaves and could be stressed by the process , however if some leaves ar blocking light to some bud sites you can remove them or try to knit them together. If you have a powder on your leaves it can be a sign of powdery mildew and you can fix that with bordeaux mixtures (many reciepes available on google) but as I can also see a kind of white powder on your "dark plastic" (at the base of your plants) I bet it is something falling of the roof or anywhere else. I hope it will help you 😁👍