Probably both factors at work.

The same happening to mine I think they go strong for a certain period then just give up due to therir own version of old age.

They seem to be coming back to life. Just got a big juicy cucumber grow in less than a week and more flowers are sprouting at the growing end. Probably was the mildew problem that got to them earlier.

If they look green and healthy, give them some fertilizer(Bloom booster type) and water regularly. Keep spraying Neem oil regularly too.

But normally, cukes have a short life span. Even without disease they get tired and stop producing. The start producing awkward shaped fruits. That is why staggered planting makes sense.

This post was edited by seysonn on Thu, Aug 22, 13 at 7:12

My first planting of cukes has looked awful for a month. The last few cukes were misshapen and then for a couple of weeks, nothing. I was ready to pull the vines, except that up at the top there were healthy looking new sprouts.

So I waited, and now I see new cukes growing. It's like the vines needed a 2nd wind. And yes fertilized and watered to give them a boost.

Mine have all but stopped producing too! Now I'm just focusing on my peppers! They are doing good.