Every thing is a band-aid except sulfur... It spreads incredibly fast - you certainly have it on other plants if it's this thick on this one. (You have it 10 days before it even shows). Look into sulfur burners...
Neem is not normally considered a control for PM - but it may work... Don't use Neem oil with a sulfur burner! A better, modern alternative to neem oil is Azarachtin - known as Azartrol, Azamax, and such... It is derived from the neem plant. In recent years, I have adopted Azatrol foliar feeds as a preventative against pests - but also as a defense against PM as Azatrol will also raise the PH of the leaf. I stop spraying by week 4. I burn sulfur weekly to keep PM away - through week 6. If PM is an issue, a sulfur burner is mandatory for your grow!
Everything, including Sulfur, is a bandaid, except for Eagle 20, I think it is called. From all I've heard, Eagle 20 is one of the only things that actually cures PM. It is vile stuff though, very toxic. I would only do this as a last ditch effort.
Neem is a catch all. It fixes everything. It may not be a cure to PM, but it is a fungistat. And I've used Neem Oil before to make my PM problem go away. Literally. 2 weeks, 2 sprays a week, after that spray every week for maintenance, it should be fixed. I haven't seen any mildew since spring.
Personally and IMO, Neem Oil works better than Aza-whatever. I haven't used the others, but I have used Azamax. The problem is that they heat treat it to process it which kill off beneficial enzymes or whatever that cause the insects to retard and eventually die off. Actual Neem Oil is cold processed, which "supposedly" has about 9 different beneficials in it that DO NOT KILL the bugs, but they retard them and make them forget how to reproduce or eat, etc. So they forget how to mate and starve to death. The first spray is to kill off the bugs on the plant, the next for the eggs that may have hatched, and then the last 2 are to pick up any stragglers. Azamax only has 2 or 3 of the beneficials that Neem Oil has, from what I understand. I have friends that have used it to great success. For me, good ole, cheap Neem Oil has been the BEST fungistat, pesticide, leaf polish, etc. that I have used. I had to use Azamax a few times, before I noticed a difference where as whether it be for bugs or PM, the effects are instant. Spray your plants, let them dry, the PM isn't there and it doesn't have a surface to attach to. Normally if I don't spray again and it is the heart of PM season, I will get 2 weeks out of the one spray before anything becomes visible again (bugs or PM.)
If you are looking to cure your plants of PM, do a round of Eagle 20 on some veg plants and keep a mom out of them. If you are looking to just keep the symptoms gone until you can harvest plants, use the Neem Oil. If none of those work, then I would suggest looking into the burner, but it won't be necessary if you spray your plants properly. And like I said before Purespray is also incredible when it comes to bugs and fungus, it just creates a surface on the leaves that PM can't attach to, so it will not manifest. And it doesn't have any poisons or toxins in it to kill the bugs or whatever. It is a 99% pure horticultural oil that will just smother the bugs, eggs, PM, or whatever else gets in its way.
Serenade works.... but not as well as Neem oil. I had a problem with Serenade cleaning up the whole plant. On light manifestations, Serenade worked good. On heavy manifestations, Serenade didn't cut it. And it stinks. It smells like BO and beach lotion. Like fat dude working all day long BO and rank sour sweat lotion. It really is nasty, lol. You'll have to deal with the garlic smell of Neem, but it works incredibly well.
