for powdery mildue u can use,
Cinnamon oil,
garlic,
Hydrogen peroxide,
Limonene,
Milk,
Oil spray - cottonseed,jojoba,neem,sesame,
Ph up,
potaassium/sodium bicarbanate - bakin soda
sulphur,
apple cider vinegar,
or Germicidal UV-C light,
If ya wana know how much or strong just ask,
hope it helps,