I pruned my autumn raspberries in February but they haven't started growing back (I'm in East Anglia in the UK).
They were planted the year before and they did bear fruit. My plot has clay soil and is very flood prone (it's lower than the road in the allotment and has been compacted by walking over it). During some spells of very heavy rain where the water wouldn't drain, I thought it would be a good idea to add as much organic material I could find, and the only thing I had available at the time was bark/pine needles, which I ended up using in large quantities. That seemed to absorb most of the water. However, after pruning them to the ground in February, they haven't started growing at all, not even a single leaf. I put the prunings into pots and some of them have started growing, there's a couple of leaves on each.
How can I tell for sure my raspberries are dead? And what could have killed them? Did the excessive bark/pine needles made the soil too acidic? Or the fact that they where sitting in water?