The leaves on the raspberries are not looking too hot. This type of yellowing seems to be a common problem and it appears that many people never manage to cure it and instead live with it. At a glance I would say the plants are suffering from an iron deficiency because the chlorosis is a general yellowing of the leaves but the veins have remained green.
I feed these raspberries with organic chicken pellets and mulch with garden compost in spring. Occasionally they may get an additional feed with sulphate of ammonia if they look like they need a boost. I noticed there was a slight yellowing last year but I left them to it and there was still a reasonable crop. I suspect the problem has become more noticeable this year due to all the rain we have been having. Plants need their water but they also need their nutrients too and with the amount of rain we have had falling on our soils these are being leached away.
The Solution - I will give the entire plant a good soaking with a seaweed plus sequestered iron feed. This should green up the leaves very quickly confirming it is an iron deficiency. I will then repeat this every few weeks whilst they are growing. I don’t like the idea of having to do this year in year out as the solution so I will look into any underlying factors that might be making the problem worse. The first thing I will take a look at will be the garden compost that I add each spring. I have no idea as to what the pH is and I am now discovering it is not unusual for homemade compost to have a pH as high as 8….. voilà, we have our cause. Could it be that simple?