I'm not seeing any powdery mildew, thankfully... I'm seeing what might be some insect damage (maybe spider mites, maybe thrips) .. I would get some Dr. Zymes Eliminator or some Spinosad and if you see an increase in the small white markings, get to spraying with either one of these - they're both organic (although Canada does not consider Spinosad to be organic for some reason) and can be sprayed all the way through to harvest if need be... If you need to use either one, always spray just before lights out..
Good luck!