Quote Originally Posted by PharmaCan
I guess doing some research was just too much effort for you. Well, now you see the consequences of impetuousness and laziness. Perhaps next time you will know to avoid both.
Let's rub some more salt in his wounds, shall we? :thumbsup:

Go grab yourself a bottle of SMC leaf wash, which is coriander oil concentrate in horticultural oil. It treats and prevents PM and other fungus.

Also, an organic fungicide such as Serenade, which contains Bacillus bacteria, is another preventative step.

Your humidity is low to be seeing PM... but stranger things have happened. I don't know how you got it in such dry conditions. You might want to pay closer attention to the differences between night and day temps. You could be getting dewfall after lights out if the swing is more than about 15 degrees or so, even at that low daytime %RH.