I planted 3 Prelude raspberries in April. They looked fine for a couple months and grew a few inches, but then they slowly started to deteriorate. Even though I kept them watered, they gradually seemed to turn brown and then (I assume) die. I have one that's barely hanging on, but watering doesn't really seem to help.

What could be wrong? Also, is it possible that the roots are still alive, even if the tops have died? Thanks for any info.