My plant got this overnight it seems. White dots appear like if someone 'flicked' salt water at my plant. Also it's been doing this for a while. Leaves are drying up at the bottom. As they dry I have to pick them off. Here's a leaf from the bottom of the plant showing the condition. I started bringing in my plant during the night time because it started flowering. I sit the plant under a small florescent and uv light, about 75 watts. There are deffs no signs of spider mites, or webs for that matter. Did wattering the plant in the closet create a mildew? Is mildew air born? and what do I do about the yellow leaves drying up?
Mild Calcium deficiency can cause the "water spots" you're seeing. It provides structure & rigidity to cell walls. When a plant goes too long with a slight Ca deficiency, these walls break more easily. If that's the case, the white powdery stuff on the leaves would be cell walls breaking apart. Phosphorus deficiency can cause the yellowing & necrosis and aggrevates Ca deficiency. A good, strong, Bone Meal tea should prevent further damage for awhile. The damage you already have won't heal itself- the best that could happen is it doesn't get worse.
Update: I let a friend water my plant while I was gone. He in fact watered the leaves causing these dry spots. I completely decontaminated the grow room for nothing. Or at least not for what I was trying to do. The yellow leaves are still a big problem though.