One of the many cucumber diseases (see link below). Best guess is Angular Leaf Spot.

http://vegetablemdonline.ppath.cornell.edu/DiagnosticKeys/CucurLeaf/CucLeafKey.html

Dave

had something similar start last month. I tried pruning all effected foliage but even the new growth as it started was all browned on the tips.

Welcome to gardening!

Still cannot figure why they died ideas?

"Still cannot figure why they died ideas?"

Not sure what you mean? They died from a disease. The only question is which one of the several possibilities. Did you check out the link I posted to all of them?

Cuke diseases are quite common - just note the hundreds of posts here about them. It happens all the time. Most are fungal diseases caused by fungi that are all around us all the time and only waiting for the ideal weather conditions to thrive; some are bacterial. If you don't want diseases then you use fungicides religiously from the day of plant out OR like most of us you rip out infected plants at the first sign and replant.

Dave

any resistant cultivars ?

There are cucumber varieties that are resistant to bacterial wilt caused by cucumber beetles like County Fair and a few others but few if any are resistant to fungal diseases. There are some squash varieties that are PMR (powdery mildew resistant) but the resistance in not very great IMO. Best bet is to do as Dave suggests and treat with fungicides early and often.