Powdery mildew is puzzling me....

...I had it once before, but that was mostly because of poor air circulation. This time, I have 9 Blue Hash plants that have it bad, but a group of 8 plants right next to it (mostly indicas) have no sign of PM....Im guessing its a strain thing. (BTW, my humidity is around 20%)

Anyways, Im a bit worried.....I noticed the plants were infected when I got home from a trip, so I sprayed with Seranade 7 days ago, however I did not clip off any infected leaves. Now, the problem is getting worse...plant growth may be slowing a little bit. Before I use this next batch of serande, can anyone recommend anything else I should do/use? Im definitly going to clip the badly infected, but damn, the PM is on main stalk on many of these, some worse than others!!!! Im not ready to kill these, so someone please help save my girls!!

Thanks!!

Same problem, I read somewhere, that even though your temperature & humidity are low it's still possible to get powdery mildew if the plants are too close together. BUMP for some help!

try a sulpher burner i just ran a search for it with hydroponics and found some....maybe theres a diu sulpher burner in the faqs?? hope that helps