I'm not sure if you'll remember, but I was having a nightmare of a time with the majority of my cucumbers just before Christmas. The leaves on them were browning up to the new growth, which was a healthy green colour, then those leaves were turning brown too.
To this day I don't know what was wrong with them, I had thought it may of been environmental, the tunnel house was too hot for them and the leaves were burning. Other years I had always grown taller plants among them so they would of shaded them a little.
But, as you can see what ever was wrong righted itself, just in time! I was almost at my wits end and tore them all out, thank goodness I held off! All I done was feed, feed, feed them and they sure are thriving now!