Cutting the visible portion of the surface roots is not recommended. We recommend burying the roots by rebuilding the grass around them as follows. Scatter roughly one-half inch of organic topsoil around the exposed root. Soak the area until you can no longer see the new topsoil. Permit the grass to grow and repeat the procedure in a week to ten days. With three or four applications the root segment should be hidden. Treat a sufficiently large area around the root segment to minimize any mounding effect. Alternatively, you may wish to place mulch around the tree as a means of concealing surface roots and producing a grass-free environment conducive to better root growth. Grass removal is not necessary; three to four inches of mulch will bring about decline and death of grass. A mulch circle of eight feet is a start. Enlargement may follow, year after year, if desired.