Round up and no asparagus have nothing to do with each other unless you’re continually spraying R up on it. Asparagus is sorta hard to kill.  Old school varieties going back to where old school varieties were is fine BUT going back to where hybrid varieties were is a no no. 

MSU has an asparagus research station just north of Hart Mi they might be of help another option is calling Alan L at Helena in Shelby MI smart guy and he’s in the heart of asparagus country.