Hi James,

I've found an easy-to-follow fact sheet "How to Plant a Tree" from the University of Missouri Extension Service:  https://extension.missouri.edu/publications/g6850.

To answer your specific question, the root ball of a balled and burlapped tree is generally left intact, unless roots are obviously circling the trunk.  Those are girdling roots and should be cut.  In fact, any burlap and/or wire basket are left intact as well, but -- as you will read, make certain that those materials are buried by the planting soil.

Good luck with your new tree.

Glad we could be of help. We will always recommend actions based on scientific and academic research usually from the Extension Service. Enjoy your tree!