Intrusive tree roots create problems for homeowners by seeking water and nutrients in places like utility lines or under hardscapes. Surface roots are tripping hazards, and aggressive growth can exploit cracks in driveways, sidewalks, and foundations, causing them to lift and buckle. Since a tree’s root system is fundamental to its stability and health, removing roots requires careful consideration. The following methods focus on managing existing root issues and preventing future encroachment without causing the tree to decline.
Mechanical Removal Techniques
Physical root removal is the most direct method for dealing with surface roots or those accessible near structures. The process begins by exposing the root fully using a shovel, mattock, or high-pressure air spade to clear the soil without damaging the surrounding root system. Once exposed, use sharp tools such as loppers or a root saw to make a clean, precise cut perpendicular to the root’s length. Clean cuts compartmentalize the damage more effectively than ragged tears.
Never sever a root with a diameter greater than 10% of the tree’s trunk diameter, measured 4.5 feet above the ground. For large, mature trees, roots exceeding four inches are often structural support roots; cutting them compromises stability and can lead to windthrow. If the root is too large to cut safely, or if the tree has been removed, a mechanical stump grinder can chip away the remaining stump and surface roots a few inches below the soil line. This grinding removes the immediate hazard but does not eliminate the entire underground root network.
Chemical Treatments for Root Eradication
Chemical treatments are reserved for roots that have infiltrated inaccessible areas, primarily sewer lines and septic systems. These products use agents that kill the roots locally without harming the entire tree. Foaming root killers, which often contain the herbicide dichlobenil, are highly effective because the foam expands to fill the entire pipe diameter, coating roots growing from all sides of the sewer line. Dichlobenil acts as a growth inhibitor, preventing the regrowth of new root tissue within the pipe.
Copper sulfate is another common chemical used in sewer line treatments, typically flushed down the drain. It is toxic to the roots it contacts but can be hazardous to aquatic life if it enters waterways, and must be avoided with septic systems as it disrupts bacterial action. Systemic herbicides, such as glyphosate, are sometimes used to treat a removed tree’s stump, but applying them to a live tree’s roots can travel through the vascular system and potentially kill the entire plant. Always use localized treatments for sewer issues and read product labels carefully to understand environmental risks.
Long-Term Strategies to Manage Root Growth
The most effective long-term solution is preventing root intrusion by following proper planting guidelines. Select appropriate tree species known to have less aggressive root systems when planting near pavement, foundations, or utility corridors. Ensure the tree’s trunk is positioned at least 15 to 20 feet away from any structure or underground line.
For existing trees, physical root barriers provide a reliable way to deflect root growth away from vulnerable areas. These barriers are typically made from high-density polythene or fiberglass and are installed vertically in a trench between the tree and the structure you wish to protect. To be effective, the barrier must be buried to a depth of at least 24 to 36 inches, as most invasive roots grow in the top few feet of soil seeking oxygen and water.
The barrier should also feature a ribbed design to guide exploring roots downward, encouraging them to grow underneath the barrier rather than attempting to grow over it. Strategic root pruning can also be performed, which involves cleanly cutting a root at a distance from the trunk and then installing a root barrier in the trench to redirect future growth into a safe zone. This planned intervention allows the tree to compartmentalize the injury and maintain a stable root plate in the opposite direction.