Mr. David,

Depending on the size of your pine and the size of the sassafras, a prescribed burn would "discourage" the woody vegetation in the stand, and promote the establishment of more herbaceous ground-cover.

A more long-lasting solution would be to spray the sassafras in August or September with an imazapyr herbicide (or use a "hack and squirt" method if the trees are too tall), BUT REMEMBER, this herbicide is soil-active and if there are desirable plants under the pine you don't want to kill, then glyphosate would be a better choice.

You mention that the stand is "plagued" with sassafras. Is the basal area per acre in "undesirable" trees over 50 square feet? If not, removing the "undesirables" may not be cost effective. That's based on studies of mid-rotation release in southern pines which found that one square foot per acre of understory hardwood competition reduced pine growth by about one cubic foot per acre per year. And I put "undesirable" in parenthises because any tree, depending on the situation and where it's growing, can be "undersirable". (Sassafras produces a drupe in late fall to early winter that can provide soft mast for wildlife.)