Tree Roots, Underground Menaces

The 2011 summer and fall saw significant rainfall in Florida followed by drier conditions.  As such, isolated turf stress from nematodes and tree root competition has been observed on recent Turfgrass Advisory Service visits.

Trees are important features on golf courses as they add beauty, provide food and shelter for wildlife and impact golf course strategy and playability.  However, trees also negatively affect turf health as they compete with turfgrass for sunlight, water and nutrients.  Some trees, like live oaks, produce extensive shallow root systems that aggressively compete with turf for water.  Such trees can literally suck the life out of adjacent turf and create brown, droughty conditions – a fact that is often missed when golf course managers focus on shade issues alone.   

Tree limbs are pruned on a regular basis to improve turf health and golf course aesthetics.  However, few courses prune tree roots.  Root pruning is recommended for shallow-rooted trees at least every other year.  Trees produce new roots that eventually stress the surrounding turf, so it is necessary to prune tree roots regularly to maintain good turf quality.

Ideal pruning depth is at least 12 inches, as bermudagrass seldom produces deeper roots.  How close to the tree should you root prune? Even tree experts don’t always agree on what is safe since factors such at the age and health of the tree, and even the soil it is growing in, can make a big difference. As a general rule, err on the side of caution and avoid pruning inside the tree’s canopy if possible.

There are several implements that can be used for pruning tree roots, including trenchers, stump grinders or vibratory plows.  Some of these can create bare areas that take time for adequate turf recovery and it is generally recommended to plant new sod to reduce unsightly conditions.  However, there are newer implements, like the Imants root pruner (www.rootpruner.com), that create thin slits that are barely noticeable to golfers.

Source:  Todd Lowe, tlowe@usga.org or 941-828-2625