That is DEFINITELY NOT powdery mildew... not on your life! Those are insects (and thrips to be precise) and they need to be gotten rid of quick time. Grab yourself some Dr. Zymes Eliminator or, if you can't get that where you live, some Spinosad.... both are organic, both can be used without damaging anything (except the insects) right up to harvest ... they will kill the adult/larvae/eggs of thrips, spidermites, aphids and whiteflies and it's always good to have one of them on hand. Just spray as directed just before lights out....
Cheers...