Re blueberries, this URL says "prune back to new wood". The meaning is not obvious to me. They don't say to remove all old wood, from the base. In fact, from the context, the rule seems meant to apply to tips/ends. But, wouldn't any such necessarily be 'newer' than what they're growing out from?
If you have some old wood that needs pruning, you prune it back to where new wood is arising off that old wood. On roses this might be a few inches above from where the stem originates.
This is another example of the term found on a home orchard forum about pruning blueberries from Gifts of the Planet Farm in Washington:
First get your pruning done me March 15th if at all possible.
Start at the bottom and prune any low spreading branches that will droop to the ground with berries. Next, thin the center of the plant if it is too crowded. Next, remove twiggy old growth that will produce few berries. One rule is to prune back to new wood (easier to ID on some varieties). Finally remove the laterals that will produce berries to far inside the plant ( hard to pick) or that are too far out (on a limb) from the center, that will droop toward the ground when loaded with fruit. Remember most berries are formed on 2 and 3 year old wood.
Fertilize twice (I like Fish Emulsion) in the spring after flowering and before harvest.