Methods used to control tree roots

1. Killing all roots in a given area.
   Roots are cut or killed with chemicals in a given area. It is critical to know how close to the tree a Kill Zone can be created. Structural damage can result if structural roots are destroyed. Also, pathogens can enter damaged roots. Improper use of chemicals can damage more than just the desired area.

2. Modifying soil conditions so they are unfavorable to root growth.
   Soils must have certain characteristics if tree roots are to grow in them. If a soil characteristic is changed beyond these limits then tree roots will not grow. For example, if pH is raise above 8.2 then tree roots can not grow. Unfortunately, the roots of most woodland plants would not be able to grow in that soil.

3. Creating air gaps so roots dry out.
   Roots require moist conditions to grow in. If a soil has only large pore spaces it can not hold water. If the soil drains well then any roots entering it will dry out and die. Such soils must be free of silts and clays.

4. Installing barriers that roots can not grow through. Traps. Screens, welded fiber sheets, and woven and nonwoven fabrics. The holes in the material allow the root tip to grow into or through the material which then girdles the root as it grows.

5. Deflectors. Deflectors are solid sheets of material that change the normal root orientation, excluding root growth in a area.

6. Inhibitors    Inhibitor growth barriers use chemical control agents to constrain root growth.

7. Encouraging growth to areas where roots are desired.
   By providing ideal growing conditions in the area you want tree roots to grow. Or creating trenches, channels, layers, tunnels etc. that have ideal growing conditions.

8. Planting species that have desired root characteristics.
   This means selecting the right tree for the site and soil conditions. Many times problems develop because the tree looks great the first few years it was planted but as it grew it became a problem.

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