In SC we didn't have much of a winter and mildew is here already. Chamomille tea is brewing right now on the kitchen counter to be sprayed before nightfall. Add a Tablespoon of murphys oil soap and another of baking soda and spray daily.
This has always worked for me EXCEPT the spray daily part.
My perennial plants seem to do fine with out my help but the squashes, zuchinni, yellow squash and cucumber all seem to need a little protection.