In the woods behind my house I have manually cleared out a lot of blackberry and left many of the native plants like salmonberry, trying to give it a chance to take better hold. Two of the salmonberries in the last year or so have died. Large bushes with now just standing dead wood. There are quite a few more that are fine, many have grown quite a bit now that they have more room. I don't know much about this plant and I'm curious, is this dying off a normal part of the life cycle? Is there something else going on to cause what was, a few years ago a seemingly healthy plant dying so quickly?
If it helps, those larger dead plants and canes eventually become home to moss which helps feed a lot of little things. I use them for spawning mops when the annual goldfish spawn hits ;) But, it's not entirely dead. Clean it up a bit, but try to let nature reclaim parts of naturally too. One thing I have been wondering is if berry color is related to cane age?
Do you mean golden versus deep red? No, it is genetic. The questions as to the why of that are being investigated as I write this by folks at UBC. There should be a social media post about it from the garden either now or soon.