Have a couple of older blue spruce trees (not sure of exact species). The bottom branches appear to be dead. Is it OK to cut them off? I think someone once told me that you should not cut them. I think the trees are 25-30 years old.
Dead limbs can be pruned during dry periods any time of the year. Blue spruce trees do not do well in Minnesota and yours might be suffering from Cyrospora canker which affect lower limbs first then works it's way up the tree. From more information see http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/spruce-tree-diseases/cytospora-canker/