hey akil,
totally agree with JIFFA, hard to be 100% due to pics but i think it's powdery meldew.
i have had it on my last 2 grows but it did'nt start for me until week 5 or 6 of flower so
it did'nt get progress enough to ruin buds in the few weeks before crop.
i used 2 diff sprays from grow shop, 1 was bio gold or summat like that can't remember da other.
but they were both

, just came back even thicker.
MY ADVICE: try to get rid asap as once it takes hold it WILL blanket your whole crop (trust me)
it only starts on lower leaves at first but if not treated it WILL progress to all leaves and da bud.
was also harder to treat for me as i was dealing with 30 or so plants.
hope ya sort it mate

good luck..................tcc
yh thanx m8..hav a look how i sorted it

i cudnt see my babys in that state
