If you are spraying your plants with anything its probably just left over residue. For example, if you mist your plant with hard water or nute water. Hard water will leave behind salt traces which are visible as white dust. Heavy nutrient mixtures (for foilar feeding) will leave excess residue behind. It doesn't look like powdery mildew, then again i can't enlarge your pictures because of my slow internet. Your leaves look twisted as from a pH imbalance, shift, or lockout. Your leaves also look dark green and nitrogen overdosed. If you have any yellow tips that are burnt I would only use water for 2 weeks and continue feeding at 1/2 strength. If your plant does have a pH imbalance the spots may be showing up from leaf deformation.
