Posted: 02/07/2012 at 09:32
I agree with Green Magpie, cut off badly affected leaves. It usually appears later in the season, but because of the amount of wet weather this year it's making an early entrance.
You could try this: Milk will control powdery mildew....dilute 1 part to 10 in water and spray infected plants.
It won't affect the crop. (the mildew of course)