Ronstar is not labeled for residential turf. Chemical root pruning by pre emergent herbicides has long been a converse among the agronomic community. There are two very distinct schools of thought. one which believe the benefits out weight the faults. The other which I follow, believes Pre emergents do more damage than good. Now let me qualify my believes by pointing out I work mostly with St Augustine a solomatic turf. Pre Emergent do not effect Rhizomes because they are below the surface which has the Pre emerge barrier. Therefore Pre emerge doesn't effect C 3 rhizome turf like it does C 4 solomatic turf. Successful plugging of St Augustine should include both organic fertilizer like Milorganite and synthetic starter fertilizer like a 20-20-20. Of Course lots of water and Post Emerge Herbicides for weed control. But most important is the application of a PGR herbicide like Primo that redirect growth to decrease grow in time by redirecting growth in a lateral direction. .