Posted: 19/09/2014 at 16:15
Try searching for an Eco spray that you can buy ready made up, or make up and dilute yourself, called SB Invigorator Spray (I buy mine in amazon) - it's based on plant oils, non toxic to everything and leaves, fruit etc can be harvested straightaway.
I've been using it in my garden to control aphids, spider mites and the like, with amazing results. Because it helps the plants by giving it super healthy, invigorated leaves, it also helps to control mildew In my clematis.
i also use it a couple of times a year in my indoor plants and it rejuvenated them very well.
if this doesn't work or your mildew is too advanced, pick off as many affected leaves as you can, spray with SB, leave a week, and if no improvement use a systemic fungicide. That'll definitely control it.
But a healthy plant with healthy leaves, that isn't overcrowded and has good ventilation is also the key to reducing mildew attacks.