Here you go:
For 1 Gallon of rose fungicide for Powdery Mildew:
Follow mixing instructions as listed.
Mix the following into ONE CUP of water:
1 1/2 tbs, baking soda
1 tbs. canola oil
1 tbs. Insecticidal Soap ("Safers" is a good brand)
1 tbs. WHITE Vinegar. Add this LAST.
Stir the ingredients well and add water to make 1 gallon of spray.
Apply with a pump sprayer and thoroughly wet the foliage and infected areas.
Apply when the air is calm and not too hot outside.
There are other variations of this recipe, but this is the one I've used for years and it works very well.
If your infestation isn't too severe, you should be able to see the mildew "vanish" as you spray. The spray neutralizes it.
You can reapply the spray about two days later if needed...but mix up a new batch if you do.
