Make sure you have plenty of air circulation both above and below the canopy, and maybe consider some selective pruning below the canopy to open it up for better circulation. I'm not convinced you have PM-google yourself up a bunch of pictures and compare them. Many times people think they have PM when it's actually just water residue. Regalia is awesome stuff, I love it, but even a fan like me doesn't always use it due to price. One cheap thing you can do to induce a SAR response is to feed/spray aspirin water-just crush up one aspirin per gallon of water (get cheap aspirin with no coatings). I always use some sort of wetting agent or aloe juice for my foliars, they just work so much better that way-also, test spray a branch to make sure you aren't going to kill anything on my advice LOL-I keep a test plant in my mother tent that I just abuse with foliars to no end. Another good, CHEAP, thing to have on hand is Potassium Bicarbonate. It can burn plants if you run it too concentrated, but it's a great treatment and preventive for PM (so is neem mixed with silica.) Aspirin is really underrated though, it has both a systemic and a contact effect on fungus, and they even use it as a postharvest treatment on many types of fruit to prevent botrytis. Good luck!
