By Bonnie L. Grant
Invasive tree roots are a common problem for homeowners and in commercial settings. They interfere with streets and sidewalks, sneak into septic lines and cause trip hazards. Tree root problems are not always solved by the removal of the tree, as the stump or remaining roots may continue to grow. It is best to look at the type of tree and the suckering ability of its roots beforehand and then deal with the issue on a case-by-case basis.
Understanding Tree Root Systems
Trees use their roots to provide stability and gather water and nutrients. The types of tree root systems vary from shallow to deep, wide to narrow. Some have massive taproots and little peripheral root growth.
Others, such as many conifers, have extensive root masses that spread far out from the base of the tree in search of resources. These types of trees have deeper spreading roots and surface feeder roots.
Feeder roots branch and send out smaller growths to capture every bit of water and food for the plant. Surface roots that grow large can break the surface of the soil and cause tree root problems.
Tree Root Problems
Tree maintenance difficulties and safety are two primary root issues. Large root structures prevent mowing and other activities, and may pose a walking hazard.
Roots crack and crumble cement and concrete and may even damage building foundations if the plant is too close to a structure.
One of the most common tree root problems is introduction into plumbing or sewer systems. Invasive tree roots are seeking nutrients and water and such pipes draw them in for the growth. Once inside the pipes, they cause leaks and plug up the line. This poses an expensive and extensive repair that most homeowners would like to avoid.
Problem Tree Roots and Planting
Of course, hindsight is twenty-twenty and it is best to choose plants that have well controlled root systems in your garden. However, sometimes you purchase a home with existing trees or you might be uninformed when you install a problem plant.
Knowledge about problem tree roots and planting only those with non-invasive root systems is the ideal situation. Some tree root systems such as Japanese fir, Acacia and Vine maples are considered minimally invasive. CalPoly’s Urban Forests Ecosystems Institute has a list of other plants with low root damage potential and other attributes to help you avoid tree root problems.
How to Control Invasive Roots
The repair costs from invasive tree roots can add up. The wise homeowner should learn how to control invasive roots to avoid and minimize these problems.
Tree removal is often the only answer and the stump should be ground to prevent the continued growth of roots. Freshly cut stumps treated right away with glyphosate will usually kill the roots. If you cannot afford stump grinding, drill holes in the stump and cover it with soil or fill them with a stump decay accelerator.
Install a root barrier around young trees at a depth of 18 to 24 inches in a trench around the root zone.
Again, the best method to prevent tree root problems is prevention and proper tree selection and location.