On Sun, 27 Aug 2017 10:51:42 +0100, Broadback
wrote:

It is the time of year attend my raspberry canes, removing last years
and tying up this years growth. I notice a lot (most) have a bright
yellow/orange "stain" on the underside of the leaves. These look like
they could be areas of small insect eggs, what is the most likely cause?
Will it give me problems next year?

I have had this problem before, does not effect the fruiting, and I
controlled it to a certain degree by removing all the leaves before
they fell, and getting the soil clean under the bushes, in case I
missed anything, my bushes now look as good as ever.