I can't tell from that first picture but looks like theres lil black spots on there. Can you see them crawling around on that web? if so, spider mites is very likely....
... the other 2 shots of the white spots look like a fuzzy fungus and if in fact it is fungus/mildew it would mean the humidity is high and spider mites don't thrive in high RH. I believe it would be best to go out and get a fungicide/miticide. I think Safer Soap is made for both, check em out, I've found them at regular super markets a few dollars cheaper than the hydro store. $5-7 for a lil all-in one spray, not the aerosol spray though those are really strong, especially on clones IMO.
I agree with bloody about taking the dome off and cutting the damaged leaves only after you tried to see if the stuff will come off with, say, a Q-Tip.
Good Luck. |