Cucumbers leaves going yellow and crumbly

Hi, 

I planted out my cucumbers on the weekend and since then the leaves have been deteriorating. They are going crumbly and have white/brown patches on them and some look slightly yellow. I have had a look for insects and I pulled a few aphids off and I came across something brown that jumped away. Any thoughts on what I can do to save them before all the leaves start turning this way? 

The new growth looks healthy and there are plenty of flowers. 

These are the first things I have grown from seed so I really want to try and save them!

Thanks