Ailment No1 ... Cucumber

Bought  a number of F1 Cucumber plants ... all kicked off well ... then 2 weeks in one of them looks particularly sickly ... limp leave with discolouration ... as per pic.

In case it was mineral take up, I sprayed last 3 days with Epsom salts .... but no improvement ... any clues ...the nearest in my book mentions 'mosaic virus', do I remove damaged leaves or trash the plant if it is.
Other plants are fine.

My money would be on transplant shock too. Where'd you get it from and in what conditions did they have it. It's still very early to be putting cukes anywhere unheated.

all plants bought form local garden nursery used them every year.

All were potted and put in unheated greenhouse the day I bought them ... all others are fine .... will it recover or do I get rid of it ?

In my experience once a cuke goes like that it does not recover. 

You could be right Springy, but I am all for giving it a go, taking off that dodgy leaf and see how that others get on. If another leaf goes, time to scrap the plant I feel