I have battled powdery mildew on my rose bushes for years, and find that a light mist of neem oil once a week really REALLY works to prevent it.
Never spray neem to the point of runoff, just mist lightly, dry, and repeat a few days later.
The glossy film that builds up acts as a prophylactic against a wide variety of molds, diseases, and pests.
Serenade is B. subtilis, a beneficial bacteria- both Serenade and Neem can be used in organic gardening and are COMPLETELY non-toxic to humans. Word.
stinkyattic Reviewed by stinkyattic on . powdery mildew on bubba/master kush plants Hi All, I have read up on my problem and have determined it to be powdery mold. At first I thought I had gotten dust on the plant, but now that it is on newer leaves I had to rule that out. So...I clipped off the most affected leaves this morning and increased ventilation in my vegging room. I had the fan going off with the lights as I have them on 20/4, it will stay on now. I made the area larger to avoid crowding. I only have a white widow and a Grandaddy purple in there with Rating: 5