any other ideas what could be causing this or is it normal for a few cuc leaves to die each week as the vine grows?

Link below is to several discussions of the same question that the search pulls up and will answer your question. Looks like you have both powdery and downey mildew problems and both are discussed in the link. Dave Here is a link that might be useful: Squash leaves turn yellow discussions

The label should tell you if you need to wait a certain number of days to harvest. IIRC, Daconil has no wait time to harvest when used on tomatoes. It would be almost impossible to avoid spraying your fruit if you're spraying correctly. Remember that you have to spray all stems, foliage (both top and underside), and preferably also all developing fruit as well. If you can do that and avoid getting anything on mature fruit, you are very talented.

Looks like its getting burnt to a crisp. When did you plant it? If it doesn't have any roots set up, it's getting blazed with hot sun, and you fertilized it, I think that would cause the burning. There could be something wacky with your soil too.