There are a few ways to keep your red raspberry bushes trimmed. In the long run you want the lushest and tallest branches left. If you see any weak or damaged vines, prune them. This help prevent disease among the plants. Also, make sure they are properly spaced and off the ground. If you do have any old branches, leaves or bushes, trim them as well to help keep away pest that could be attracted to them. The idea is to have a healthy plant that produces more berries!
Read more: Easily Prune Your Red Raspberry Plant