Answer: Perhaps there must be something unique to this location? The usual preventive measures used for mildew (and other foliar problems) include exceptional garden sanitation (clean up and remove all traces of infested plants as they happen and at the end of the season), avoiding watering at night or wetting the leaves, increasing air circulation, rotating crops, and growing resistant varieties. You might wish to look at the photographs at this site http://www.ext.nodak.edu/extpubs/plantsci/hortcrop/pp656w.ht... to see if it really is mildew and to consider some of their IPM suggestions. Finally, you might wish to contact your County Extension for their most current control recommendations -- often timing is very important when spraying for diseases.
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