I would look for the Squash Vine Borer which will go after Cucumbers as well as squash.

Here is a link that might be useful: About Squash Vine Borer

Certainly check the vines for borers, but several experienced gardeners were just discussing this evening how their cuke plants are pretty much done ... they do that after a while in the heat ... that is why successive plantings are recommended to extend the harvest.

that is why i gave up on them.. decades ago ...

since i dont pickle them.. there is simply no use for too many.. and when they are done.. they are done .. so be it..

eventually.. i just quit planting them... who needs the irritation ...

too many newbs to gardening.. think its all a disney-esque .. perfect little world.. it isnt.;.. short seasons... long seasons.. most everything produces.. not much looks perfect ...

cukes are short season .... get ugly.. and die ... so it is said.. so it is written ... lol ..

whether it is a disease.. or a bug.. what difference does it make.. the cure costs more than a bushel basket of cukes at the farmers market this time of year ....

ken

I would suspect bacterial wilt, which is spread by cucumber beetles.

Here is a link that might be useful: cucumber wilt

Bacterial wilt takes some time to affect plants, starting with the leaves and then spreading throughout the plant. Affected leaves often will wilt during the day and recover at night with Bacterial wilt while they will not if the plant is infected with the borer larva.
While I have seen plants exhibit signs of sudden wilt when borers are present I have not seen signs of sudden wilt if just Bacterial Wilt is present, leaves slowly turn yellow and then wilt.

Here is a link that might be useful: Bacterial wilt