Seeing from the picture, it is a wound caused by the larvae (wood chiseling bug) of the asparagus (it has been harmed for years, just that you didn't care about it).

Because the wound is so large, there is no longer a need to control it, so we suggest sawing off the upper branches below the wound (where it is healthy) to find the wood chiseling bugs and kill them. Or place the sawed off trunks in a septic tank in a composting bar.

Keep an eye out in the summer (June-August), and when you find spotted woodchucks (a type of beetle with very long antennae), kill them to prevent them from laying eggs.