Textbooks often illustrate how tree roots extend much farther than the canopy. These roots, in particular the smaller “feeder” roots, will intensively outcompete turf for water and nutrients. When a tree has grown too large for its location – e.g., too close to a putting green, tee or fairway – the likely best action is to remove it, but removal is not always easy due to politics, aesthetic concerns, or budget constraints if a tree service is needed. This is when pruning tree roots to tip the competitive edge back to the turf is beneficial. There are several methods to consider.
A vibratory plow set 8 to 12 inches deep will sever most of the feeder roots, and a single plow line is relatively quick to make and can be smoothed out through rolling or tamping. The downsides are that severing deeper, larger roots is difficult, and the plow can bounce off them or lift large roots out of the ground, which damages the turf. Tree roots that are pruned with this process can also quickly grow back into the playing surface you’re hoping to improve.
Another method is to strip sod, cut the roots with a trencher while placing the spoils onto plywood, and install a physical barrier upright in the trench. Barriers can be made from plastic tarp material, aluminum roof flashing, or other impermeable products. Then you can backfill the trench, compact the soil and reset the sod. This method is more labor-intensive and trenches may settle; however, it has a long-lasting effect. When installing a physical barrier, ensure that drainage will not be affected and create new problems.
Tractor-mounted dual slicers designed for root pruning are another option. These machines sever tree roots in two places to minimize regrowth, and repair after slicing is minimal. The effects are limited to a few seasons as the roots will regrow eventually, and this approach does not allow for installing a physical barrier. However, it is a fast process and many linear feet can be root pruned efficiently.
Whatever method works in your scenario, ensure you track underground pipes and wires first so they are not damaged. When implementing root pruning, follow the playing surface contours or make sweeping arcs to minimize straight lines that may be visible for years due to the stark contrast between the green grass beyond the pruning line and the struggling grass still impacted by roots. As previously mentioned, the benefits of root pruning are temporary. If a tree has grown too large for its place near a playing surface, no tactic other than removal will lead to consistently healthy turf. For assistance in developing a tree management plan or making decisions about root pruning, reach out to your regional USGA agronomist.
Northeast Region Agronomists:
Darin Bevard, senior director, Championship Agronomy – dbevard@usga.org
Elliott L. Dowling, regional director, East Region – edowling@usga.org
Brian Gietka, agronomist – bgietka@usga.org