The negative effects of trees on turf health is nothing new. Shade, restricted airflow and root competition are the three main culprits. While we can usually see and feel the effects of shade and restricted air movement, visualizing root competition can be more challenging. A general rule of thumb is that tree roots will extend as far out as the tree is tall. Imagine the tree falling onto its side and this is about where roots typically extend to. That said, the best time to see the effects that tree roots have on your turf is following droughty conditions. When dry conditions persist and turf vigor declines, it becomes much easier to identify areas where tree roots are outcompeting turf for moisture and nutrients.
When it comes to surface roots, keep in mind that some species are more likely to rob your turf of essential water and nutrients than others. Silver maple, Siberian elm and white pine are just a few of the worst offenders that come to mind. Sadly, many courses were overplanted with these species decades ago – likely because they were cheap and grow fast.
It can be hard for some to imagine tree roots extending 50 or more feet away from the base of a 50-foot-tall tree. That said, I can assure you that tree roots have a negative effect on the turf that surrounds them. I was recently at a course for a tree evaluation visit while fairways where being vertically mowed. To everyone’s surprise, in several areas with brown fairway turf adjacent to poor-quality trees, we saw tree roots being ripped out of the ground by the verticutter. Most surface roots aren’t as close to the surface as these, but it sure was a great visual for nonbelievers!
If your course is full of poor-quality trees, or if you have circles of brown turf around many of your trees, consider pruning the tree roots sometime soon. Then, consider putting together a long-term tree management plan that evaluates all of the trees on the course so that poor-quality trees can be identified for removal. Sometimes the effect of trees on turf is difficult to visualize, but believe me, the wrong species in the wrong location is a recipe for poor turf performance. Your local USGA agronomist would be more than happy to help put together a tree management plan document to help guide future tree plantings and removal. Executing these plans usually results in healthier trees, healthier turf, more interesting views across the property and better overall course conditions.
Central Region Agronomists:
Paul Jacobs, agronomist – firstname.lastname@example.org
Zach Nicoludis, agronomist – email@example.com
Information on the USGA’s Course Consulting Service
Contact the Green Section Staff