the reason why i think it is mildew, is this. powder first appeared on lower leaves, then plants were sprayed with copper sulfate. (week 3) at week 7 more "powder" appeared on leaves surrounding buds (by this time most fan leaves were discarded (purple stems) except for the leaves in the buds. week 7 they were sprayed with baking soda, ph 8 water (1 teaspoon per 4 litres water) but not "re-sprayed" with "rinse" just left in the light. week 8, 3 were harvested, after 2 days of "hang drying" powder again appeared on bottom of buds, and if "broken apart" it can be seen on stem, and some in between resin. the 3 harvested were white rhino. this may be "mis-diagnosed" however, the powder on the leaves i think got into the buds - hence im thinking that the buds are infected with powdery mildew. i wonder if the problem can be washed away, unless someone else has encountered this, and knows what the problem is (hopefully someon has, and there is a simple cure... - ya happy wishing)