Do a sulphur burn, then spray with whatever your favorite product is. Although, you should NOT do sulphur burns within at least two weeks, some say a month, if you sprayed any sort of oil on the plants. The sulphur will stick to it, and in full sunlight, or grow lights, will burn the leaves on your plant very rapidly. I use sulphur burns, then spray with either Safer's garden fungicide or Serenade.
Sulphur burns are the only way to ensure that you've killed ALL the spores. Sprays are like putting a condom on after you've nutted.