Posted: 19/11/2012 at 19:34
I'm pretty sure it's powdery mildew, although it's difficult to be absolutely sure. Looking at images on Google they both look like the same as that which my grapes vine suffered from.
As you say, lack of warmth could be a factor as well as the weather being wet in the spring. I'm not sure what chemical control I can use, if any. Any ideas?