The Root System
 Douglas L. Airhart & Guy Zimmerman III

Web Site Guide: [Home]

Purpose

Right Tree / Right Place

Selecting Trees

Transplanting Trees

Mulching & Staking

Summary Diagram 

Pruning Trees

Topping Hurts!

Protecting Trees

Tree Root Myths

Pine Bark Beetles

Live Christmas Trees

Glossary

List of Figures

List of Video Vignettes

Related Links

Bibliography

 

[ Up ] [ The Root System ] [ The Trunk ] [ The Branches ]

    Selecting Trees- The Root System:

When selecting trees, make your first concern the root system. Most garden centers and nurseries will have trees available with balled and burlapped (B&B) or containerized root masses (Figure 3-1). You may find some trees bagged in plastic or nylon mesh with moist wood chips around the bare roots, or you may purchase trees from mail order catalogues as bare root specimens.  Whichever root mass you are considering, check for healthy roots. Healthy roots are firm and brown usually, and have white growing tips.  Bare roots trees may not have actively growing roots. 

Example of an Evergreen Holly - Ball and Burlap: Video Vignette - (See It Live!)

Example of an Evergreen Magnolia - Containerized: Video Vignette (See it live!)

(Figure 3-1) Example of Balled & Burlapped and Containerized Trees (L to R).

 From Making Tree Roots Visible, Part 2, Used with permission of Virginia Polytechnic Institute & State University, (Appleton et al., 2000).

The first structure to notice is the trunk flare. This is the base of the trunk where the root system begins  You should see that part of the trunk where it spreads out to become roots, like your palm and fingers flare out from your wrist. If you cannot see the trunk flare, the tree may have serious problems. 

B&B trees are the most difficult to select because you cannot inspect the roots themselves. Most suppliers will be upset if you try to remove the burlap, so you must make your inspection only looking from the outside. The burlap and twine surrounding the base of the trunk will likely be concealing the trunk flare, but you might confirm its presence by prying down the twine and burlap.

(Figure 3-2A) Excavating to Find the Trunk Flare.

Tree looked healthy in the ball, but the trunk flare was not visible after removing the burlap. We excavated almost six inches in order to find the trunk flare. The total root mass is extremely limited at the bottom of the root ball and this tree will suffer stress. Clearly, this tree had been planted too deep at the nursery.

  Recent studies indicate that field-grown trees with drip irrigation and regular root pruning will have more roots within the space of standard balls. Select trees from nurseries using either, or both, of these systems if you can.

A new problem identified to us at a recent trade show was called the “J-root”. This is a problem being caused by mechanical planting of B&B trees. As the transplant machine moves down the row digging a trench, the seedlings are set into the trench and dragged slightly in transit. This causes the loose roots to be drawn to the rear rather than spreading out in all directions. The trunk flare ends up having a “J” shape with roots growing in one direction. As the tree grows it will not be stable in the ground.

Used with permission of Tennessee Tech University, (Photo courtesy of J. Plant, 2002).

(Figure 3-2B)

Example of Good Trunk Flare and Radiating Root System. 

Note: Container mix has been washed away for this picture. You would not want to purchase a tree in this condition.

 

 

(Figure 3-2C) Root Excavation 

Before: Trunk flare is partially visible on right side with a young girdling root. No trunk flare is visible on left side of tree.

 After: Trunk flare is clearly shown on the right side (many girdling roots have been removed) and has been exposed on the left side. Note orange balling twine still exists (over the chisel handle) after four years of growth. (link back to planting depth page)

Proper tree growth requires roots that radiate uniformly out and away from the trunk. You should see the trunk flare in all directions at the base.

(Figure 3-3) Healthy Trees Have Obviously Exposed Trunk Flares.

The next concern is root attachment. With the tree in upright position, gently grab the trunk and try to sway the tree trunk back and forth. The root ball should move with the sway of the trunk. The trunk should not wobble where it enters the ball. If the trunk is loose going into the ball, it is an indication of some type of stem or root damage and should be avoided. The ball itself should be firm and evenly angled around the outside. A flat-sided ball or a squishy ball usually indicates some type of mishandling, which also should be avoided. Some balls are wrapped so tightly that you cannot verify whether the ball is intact around the roots. In this case the soil may actually fall off the root mass when it is unwrapped. If so, removed the loosened soil and treat it like a bare root specimen.

Containerized trees are more easily inspected. The trunk should be firmly attached to the root mass, the trunk flare should be obvious where the trunk enters the root mass, and you should not see large encircling roots at the surface.

(Figure 3-4) 

Inspecting a Containerized Tree.

Trunk flare is partially visible toward the front, but roots are encircling the trunk on both sides. 

A consumer might want to be cautious about purchasing such a tree.

If the specimen satisfies these conditions, you may ask the supplier to remove the container to let you inspect the total root mass. You should see an even distribution of fresh roots within and around the outside of the root mass. There should be no indication of damage to any section of the roots, and there should be no large roots encircling the bottom of the root ball. No pests should be present.

(Figure 3-5) 

Potential Girdling Roots.

Circling roots probably began when liner was in a container, but they were not severed when stepped up. If left on the root mass, they will become girdling roots when the trunk grows to that diameter.  

 

 From Making Tree Roots Visible, Part 3, Used with permission of Virginia Polytechnic Institute & State University, (Appleton et al., 2000).

Bare Root trees are usually smaller specimens, and the roots are easily inspected. Since the specimen should be dormant, you may not see fresh root growth. The root mass should be well branched but not crowded upon itself. The roots should be firm with no apparent damage or diseases present.

Some references indicate that larger specimens may be dug in the field and shaken to remove the soil, then dipped in a moisture holding gel to keep the roots moist and placed in plastic bags for storage up to a week. These trees are not nearly as heavy as B&B or containerized specimens. You may be able to make special arrangements with a nursery to select and purchase trees treated in this fashion. 		...

Purpose    Right Tree / Right Place    Selecting Trees    Transplanting Trees    Mulching & Staking    Summary Diagram     Pruning Trees    Topping Hurts!      Protecting Trees     Tree Root Myths     Pine Bark Beetles     Live Christmas Trees     Glossary     List of Figures    List of Video Vignettes    Related Links     Bibliography

 

TLCforTrees.info is maintained by: Douglas Airhart, Ph.D. Certified Arborist & Jeff Plant, Ph.D, Last Updated on: 07/11/03