From the time a spore germinates to the time new spores form may require only 48 hours. High humidity favors spore formation while low humidity favors spore dispersal. Maintaining conditions that favor rapid drying of foliage will help reduce disease incidence. Locate susceptible plants in open areas where they will not be crowded. Plants in shade are more prone to mildew than are those growing in sunlight.
Powdery mildews are generally most severe on young.
A balanced fertilization program is advisable. In the fall, clean up and dispose of all mildew-infected plant debris. This will help reduce the amount of disease next year. Cover the upper and lower surfaces of the leaves thoroughly. Repeat the treatment at intervals of 7 to 14 days or as often as necessary to protect the new growth.