powdery mildew remedy

It's too late in the season for me to try this but I will definitely try it next year.  A natural remedy I read about today for powdery mildew is to mix 1 part milk with 9 parts water and spray your plants.  Repeat after each rainfall.  My zucchini and phlox plants get hit every year with powdery mildew and they look terrible.  Has anyone tried it?