What herbicide chemical concoction kills morning glory but not grass?

Out of luck there, must dig morning glory out by hand. I like vinegar to kill things but it will kill any other plant too.

About the only solution I have found that works is repeated spraying in the morning before it gets warm. The roots are know to grow down as much as six feet and if the roots are broken they will start sending up on or more starts from each broken root. Also remember to keep the flowers pick , pulled or sprayed to keep the seed from developing and starting new plants....I have ask the kids to go out and pick all the pretty flowers and then up them in a bowl on the table