How To Cut Tree Roots (5 Pro Arborist Techniques)

“The best time to plant a tree was 20 years ago. The second best time is now.” This ancient Chinese proverb speaks volumes, but what happens when the tree you didn’t plant is causing problems? Tree roots, those subterranean anchors of life, can become a major headache. Whether you’re dealing with roots encroaching on your property, preparing a site for construction, or simply trying to manage the root system of an existing tree, understanding how to cut tree roots safely and effectively is crucial. As a professional arborist, I’ve spent years wrestling with root systems of all shapes and sizes. I’ve learned that it’s not just about hacking away; it’s about understanding the tree’s biology, using the right tools, and employing techniques that minimize harm to both the tree and the surrounding environment. In this article, I’ll share five pro arborist techniques for cutting tree roots, along with the critical project metrics I use to ensure success and sustainability in my work.

How to Cut Tree Roots: 5 Pro Arborist Techniques

Cutting tree roots requires careful planning and execution. Here are five techniques I’ve found most effective, along with the metrics I track to ensure optimal results.

1. Root Pruning with Hand Tools

This is often the most precise and controlled method, ideal for smaller roots or situations where you need to be particularly careful about damaging surrounding structures or utilities.

Description: Using hand tools like loppers, pruning saws, and root chisels to selectively cut roots.
When to Use: When dealing with roots less than 2 inches in diameter, working close to structures, or needing maximum control over the cut.
How It’s Done: Expose the root, carefully clean the soil away from the area to be cut, and make a clean, angled cut using the appropriate tool. For larger roots, use a root chisel and hammer to score the root before using a saw to complete the cut.
Why It’s Pro: Minimizes damage to surrounding areas, allows for precise cuts, and reduces the risk of spreading disease.

2. Air Spading

This technique uses compressed air to remove soil around roots without damaging them, allowing for a clear view and easier cutting.

Description: Employing a specialized tool that delivers a high-pressure stream of air to excavate soil around roots.
When to Use: When you need to expose a large area of roots without damaging them, locating utilities, or preparing roots for grafting or other treatments.
How It’s Done: Direct the air spade nozzle at the soil and gradually work around the root system, removing soil and exposing the roots. Once the roots are exposed, you can use hand tools or other methods to cut them.
Why It’s Pro: Minimizes root damage compared to traditional excavation, exposes a large area quickly, and can be used in sensitive areas.

3. Vibratory Trenching

This method uses a vibrating blade to create a narrow trench, severing roots in its path.

Description: Employing a machine with a vibrating blade to cut a narrow trench through the soil and sever roots.
When to Use: When creating a root barrier, installing utilities, or preparing for construction.
How It’s Done: Operate the vibratory trencher along the desired path, ensuring the blade is deep enough to cut the target roots. Backfill the trench immediately after cutting to prevent soil erosion and root desiccation.
Why It’s Pro: Efficient for creating long, straight cuts, minimizes soil disturbance compared to traditional trenching, and can be used in tight spaces.

4. Root Sawing with Specialized Equipment

This technique uses a specialized saw with a reciprocating blade designed to cut through roots quickly and efficiently.

Description: Utilizing a root saw, a powerful saw with a reciprocating blade designed for cutting through roots.
When to Use: When dealing with large roots, removing stumps, or needing to make precise cuts in confined spaces.
How It’s Done: Carefully position the saw blade against the root and apply steady pressure while operating the saw. Ensure the blade is sharp and lubricated to prevent binding.
Why It’s Pro: Fast and efficient for cutting large roots, provides clean cuts, and can be used in a variety of situations.

5. Chemical Root Control (Rhizotomy)

This method uses herbicides to kill roots, preventing regrowth and minimizing damage to surrounding structures.

Description: Applying herbicides directly to cut root surfaces to prevent regrowth.
When to Use: When dealing with invasive roots, preventing regrowth after cutting, or needing to control root growth in hard-to-reach areas.
How It’s Done: Cut the root cleanly and immediately apply the herbicide to the cut surface, following the manufacturer’s instructions. Repeat applications may be necessary.
Why It’s Pro: Prevents regrowth, minimizes physical labor, and can be used in areas where other methods are not feasible.

Project Metrics and KPIs in Root Cutting: Ensuring Success

As an arborist, I don’t just cut roots; I manage projects. That means tracking key performance indicators (KPIs) and metrics to ensure efficiency, cost-effectiveness, and minimal impact on the tree and environment. Here’s a breakdown of the metrics I use, why they matter, and how I interpret them.

1. Root Severance Diameter (RSD)

Definition: The average diameter of the roots severed during the project.
Why It’s Important: RSD directly impacts the tree’s health. Severing large-diameter roots can significantly reduce water and nutrient uptake, leading to stress or even death. Tracking RSD helps me assess the potential impact on the tree.
How to Interpret It: A higher RSD indicates a greater potential impact on the tree’s health. If the RSD is high, I need to adjust my approach, perhaps using root pruning techniques that minimize the number of large roots cut.
How It Relates to Other Metrics: RSD is directly related to Tree Vigor Score (TVS) and Tree Stability Index (TSI). A high RSD will likely result in a lower TVS and TSI.
My Experience: I once worked on a project where the initial plan involved cutting several large roots to install a patio. The RSD was estimated to be over 4 inches. After consulting with a certified arborist and analyzing the potential impact, we redesigned the patio to avoid cutting those large roots. This resulted in a lower RSD (less than 1 inch) and a healthier tree.

2. Root Cutting Time (RCT)

Definition: The total time spent cutting roots, from initial excavation to final cut.
Why It’s Important: RCT directly impacts labor costs and project timelines. Efficient root cutting techniques can significantly reduce RCT.
How to Interpret It: A high RCT indicates inefficiencies in the root cutting process. This could be due to using the wrong tools, inadequate planning, or unforeseen obstacles.
How It Relates to Other Metrics: RCT is related to Equipment Downtime (EDT) and Labor Cost (LC). High EDT can increase RCT, leading to higher LC.
My Experience: I was once involved in a project where we were using hand tools to cut roots for a utility installation. The RCT was extremely high, and the project was falling behind schedule. We switched to using a root saw, which significantly reduced the RCT and allowed us to complete the project on time.

3. Root Regrowth Rate (RRR)

Definition: The rate at which roots regrow after being cut.
Why It’s Important: Rapid root regrowth can lead to further encroachment on structures, necessitating additional root cutting. Tracking RRR helps me determine the effectiveness of root control measures.
How to Interpret It: A high RRR indicates that the root control measures are not effective. This could be due to improper application of herbicides or the tree’s natural vigor.
How It Relates to Other Metrics: RRR is related to Herbicide Application Cost (HAC) and Root Barrier Installation Cost (RBIC). If the RRR is high, I may need to increase the frequency of herbicide applications or install a root barrier.
My Experience: I once worked on a project where we were using herbicides to control root regrowth. However, the RRR remained high. After further investigation, we discovered that the herbicide was not being applied correctly. We adjusted our application technique, and the RRR decreased significantly.

4. Tree Vigor Score (TVS)

Definition: A numerical rating (typically on a scale of 1-5, with 5 being the healthiest) that assesses the overall health and vitality of the tree. Factors considered include leaf color, canopy density, branch dieback, and presence of pests or diseases.
Why It’s Important: TVS provides a baseline assessment of the tree’s health before root cutting and allows me to monitor the impact of the root cutting on the tree’s overall condition.
How to Interpret It: A decrease in TVS after root cutting indicates that the tree is experiencing stress. A significant decrease in TVS may necessitate additional care, such as watering, fertilization, or pest control.
How It Relates to Other Metrics: TVS is related to RSD, Water Uptake Efficiency (WUE), and Nutrient Uptake Efficiency (NUE). A high RSD can negatively impact WUE and NUE, leading to a lower TVS.
My Experience: On a project involving significant root cutting near an old oak tree, I carefully monitored the TVS. After the root cutting, the TVS dropped from a 4 to a 3. I immediately implemented a supplemental watering and fertilization program, and the TVS gradually recovered over the following year.

5. Tree Stability Index (TSI)

Definition: A numerical rating (typically on a scale of 1-5, with 5 being the most stable) that assesses the tree’s resistance to windthrow or uprooting. Factors considered include root system size, soil type, tree height, and canopy density.
Why It’s Important: TSI helps me assess the risk of tree failure after root cutting. Severing roots can significantly reduce a tree’s stability, making it more vulnerable to windthrow.
How to Interpret It: A decrease in TSI after root cutting indicates that the tree’s stability has been compromised. A significant decrease in TSI may necessitate cabling or bracing to provide additional support.
How It Relates to Other Metrics: TSI is related to RSD, Root System Reduction (RSR), and Wind Speed Resistance (WSR). A high RSD and RSR can significantly reduce WSR, leading to a lower TSI.
My Experience: I once worked on a project where we were cutting roots near a large pine tree located near a residential property. The initial TSI was a 4. After the root cutting, the TSI dropped to a 2. We immediately installed cabling to provide additional support and prevent the tree from falling during a storm.

6. Water Uptake Efficiency (WUE)

Definition: A measure of how efficiently the tree absorbs water from the soil, typically expressed as the amount of water absorbed per unit of root surface area.
Why It’s Important: WUE is a direct indicator of the root system’s ability to provide the tree with essential water. Root cutting can significantly reduce WUE.
How to Interpret It: A decrease in WUE after root cutting indicates that the root system is less efficient at absorbing water. This can lead to drought stress, especially during dry periods.
How It Relates to Other Metrics: WUE is related to RSD, TVS, and Soil Moisture Content (SMC). A high RSD can negatively impact WUE, leading to a lower TVS and increased susceptibility to drought stress if SMC is low.
My Experience: I use soil moisture sensors to track SMC and correlate it with the tree’s overall health. After a root-cutting project on a maple tree, the WUE decreased significantly, and the tree showed signs of drought stress. I implemented a deep watering program to compensate for the reduced WUE and help the tree recover.

7. Nutrient Uptake Efficiency (NUE)

Definition: A measure of how efficiently the tree absorbs nutrients from the soil, typically expressed as the amount of nutrients absorbed per unit of root surface area.
Why It’s Important: NUE is a direct indicator of the root system’s ability to provide the tree with essential nutrients. Root cutting can significantly reduce NUE.
How to Interpret It: A decrease in NUE after root cutting indicates that the root system is less efficient at absorbing nutrients. This can lead to nutrient deficiencies, which can weaken the tree and make it more susceptible to pests and diseases.
How It Relates to Other Metrics: NUE is related to RSD, TVS, and Soil Nutrient Levels (SNL). A high RSD can negatively impact NUE, leading to a lower TVS and increased susceptibility to nutrient deficiencies if SNL is low.
My Experience: I perform soil tests to analyze SNL and correlate it with the tree’s overall health. After a root-cutting project on an oak tree, the NUE decreased significantly, and the tree showed signs of nutrient deficiencies. I applied a slow-release fertilizer to compensate for the reduced NUE and help the tree recover.

8. Soil Compaction Rate (SCR)

Definition: The rate at which the soil becomes compacted due to equipment operation or foot traffic during the root cutting project.
Why It’s Important: Soil compaction reduces soil aeration and water infiltration, which can negatively impact root growth and overall tree health.
How to Interpret It: A high SCR indicates that the soil is becoming compacted, which can hinder root growth and reduce WUE and NUE.
How It Relates to Other Metrics: SCR is related to Equipment Weight (EW) and Foot Traffic (FT). Using heavy equipment or excessive foot traffic can increase SCR.
My Experience: I use lightweight equipment and minimize foot traffic in the root zone to reduce SCR. I also use soil amendments like compost to improve soil structure and aeration.

9. Equipment Downtime (EDT)

Definition: The total time that equipment is out of service due to breakdowns, maintenance, or repairs.
Why It’s Important: EDT directly impacts project timelines and labor costs. Frequent EDT can significantly delay project completion and increase overall costs.
How to Interpret It: A high EDT indicates that the equipment is unreliable or not being properly maintained.
How It Relates to Other Metrics: EDT is related to RCT, Labor Cost (LC), and Equipment Maintenance Cost (EMC). High EDT can increase RCT and LC, as well as EMC.
My Experience: I maintain a strict equipment maintenance schedule to minimize EDT. I also keep spare parts on hand to quickly address any breakdowns.

10. Herbicide Application Cost (HAC)

Definition: The total cost of herbicides used for root control, including the cost of the herbicide itself, application equipment, and labor.
Why It’s Important: HAC is a significant expense in projects involving chemical root control. Optimizing herbicide application techniques can reduce HAC.
How to Interpret It: A high HAC indicates that the herbicide is being used inefficiently or that the wrong herbicide is being used.
How It Relates to Other Metrics: HAC is related to RRR and Labor Cost (LC). If the RRR is high, I may need to increase the frequency of herbicide applications, leading to a higher HAC.
My Experience: I carefully select the appropriate herbicide for the target species and use calibrated spray equipment to ensure accurate application rates.

11. Root Barrier Installation Cost (RBIC)

Definition: The total cost of installing a root barrier, including the cost of the barrier material, excavation equipment, and labor.
Why It’s Important: RBIC is a significant expense in projects involving root barriers. Optimizing installation techniques can reduce RBIC.
How to Interpret It: A high RBIC indicates that the installation is complex or that the wrong type of root barrier is being used.
How It Relates to Other Metrics: RBIC is related to RRR and Long-Term Maintenance Cost (LTMC). Installing a root barrier can reduce the need for future root cutting, leading to lower LTMC.
My Experience: I carefully select the appropriate type of root barrier for the site conditions and use efficient excavation techniques to minimize RBIC.

12. Labor Cost (LC)

Definition: The total cost of labor for the root cutting project, including wages, benefits, and insurance.
Why It’s Important: LC is a significant expense in most root cutting projects. Optimizing labor efficiency can reduce LC.
How to Interpret It: A high LC indicates that the project is taking longer than expected or that the labor is not being used efficiently.
How It Relates to Other Metrics: LC is related to RCT, EDT, and Equipment Utilization Rate (EUR). Reducing RCT and EDT and increasing EUR can reduce LC.
My Experience: I use experienced and well-trained crews to maximize labor efficiency. I also provide ongoing training to improve their skills and knowledge.

13. Equipment Utilization Rate (EUR)

Definition: The percentage of time that equipment is actively being used for the root cutting project.
Why It’s Important: EUR is a measure of equipment efficiency. Increasing EUR can reduce equipment costs.
How to Interpret It: A low EUR indicates that the equipment is not being used efficiently.
How It Relates to Other Metrics: EUR is related to EDT and RCT. Reducing EDT and RCT can increase EUR.
My Experience: I carefully plan the project to ensure that equipment is being used efficiently. I also schedule equipment maintenance during periods of low demand.

14. Soil Moisture Content (SMC)

Definition: The amount of water present in the soil, typically expressed as a percentage of the soil’s dry weight.
Why It’s Important: SMC is a critical factor for tree health. Adequate SMC is essential for water and nutrient uptake.
How to Interpret It: Low SMC indicates that the tree is experiencing drought stress. High SMC can lead to root rot.
How It Relates to Other Metrics: SMC is related to WUE, TVS, and Rainfall. Monitoring SMC helps me determine the need for supplemental watering.
My Experience: I use soil moisture sensors to track SMC and correlate it with the tree’s overall health.

15. Soil Nutrient Levels (SNL)

Definition: The concentration of essential nutrients in the soil, such as nitrogen, phosphorus, and potassium.
Why It’s Important: SNL is a critical factor for tree health. Adequate SNL is essential for growth and development.
How to Interpret It: Low SNL indicates that the tree is experiencing nutrient deficiencies. High SNL can lead to nutrient toxicity.
How It Relates to Other Metrics: SNL is related to NUE, TVS, and Fertilization. Monitoring SNL helps me determine the need for fertilization.
My Experience: I perform soil tests to analyze SNL and correlate it with the tree’s overall health.

16. Wind Speed Resistance (WSR)

Definition: The maximum wind speed that the tree can withstand without being uprooted or experiencing significant branch breakage.
Why It’s Important: WSR is a critical factor for tree safety. Reducing WSR can increase the risk of tree failure during storms.
How to Interpret It: Low WSR indicates that the tree is vulnerable to windthrow.
How It Relates to Other Metrics: WSR is related to TSI, RSD, and Tree Height. Reducing TSI or increasing RSD can decrease WSR.
My Experience: I assess WSR by considering factors such as tree height, canopy density, and root system size. I also use wind load models to estimate the forces acting on the tree during a storm.

17. Root System Reduction (RSR)

Definition: The percentage of the tree’s root system that has been removed during the root cutting project.
Why It’s Important: RSR is a direct measure of the impact of root cutting on the tree’s health and stability.
How to Interpret It: High RSR indicates that the tree has experienced significant root loss, which can negatively impact its health and stability.
How It Relates to Other Metrics: RSR is related to RSD, TVS, and TSI. Increasing RSR can decrease TVS and TSI.
My Experience: I carefully plan the root cutting project to minimize RSR. I also use root pruning techniques that preserve as much of the root system as possible.

Applying these Metrics to Improve Future Projects

Tracking these metrics isn’t just about collecting data; it’s about using that data to improve future projects. Here’s how I apply these metrics in my work:

Post-Project Analysis: After each project, I review the data collected for each metric. I identify areas where we exceeded expectations and areas where we fell short.
Process Improvement: Based on the post-project analysis, I identify opportunities to improve our root cutting techniques, equipment maintenance practices, and project planning processes.
Training and Development: I use the data to identify training needs for my crew. For example, if the RCT is consistently high, I may provide additional training on efficient root cutting techniques.
Equipment Selection: The data helps me make informed decisions about equipment selection. For example, if the EDT is consistently high for a particular piece of equipment, I may consider replacing it with a more reliable model.
Client Communication: I use the data to communicate the impact of root cutting on tree health and stability to my clients. This helps them make informed decisions about tree management and maintenance.

Cutting tree roots is a complex task that requires careful planning, execution, and monitoring. By using these five pro arborist techniques and tracking the key project metrics, I can ensure that my root cutting projects are efficient, cost-effective, and sustainable. Remember, every tree is a valuable asset, and it’s our responsibility to protect them.

How to Cut Tree Roots (5 Pro Arborist Techniques)