Well, an update on the Regalia...it is NOT controlling the pm in my plants in flower, at all...In fact, it is now spreading like wildfire. The past 2 nights i have been cutting infected fan leaves off, and some lower buds that were affected. But from what I understand, Regalia is more of a preventative treatment.
Here's an excellent article that has lots of great info, including some reasons why NOT to use some of the old treatments, like neem oil.
Ultimate guide to powdery mildew cures. How to get rid of powdery mildew on cannabis fast during veg or flowering. The best organic methods
moldresistantstrains.com