Remember to Consider the Roots

When a tree or shrub develops brown leaves, wilting leaves, poor growth, or dead branches, it's easy to focus on the above-ground portions of the plant to try to figure out what went wrong. In many cases, however, the root of the problem is exactly that - an unhealthy root system.

Diagnosing problems with underground plant structures can be difficult, especially with large plants such as trees. An accurate diagnosis requires assessing cultural practices, site factors, and environmental conditions, and possibly may require a careful excavation around the base of the plant.

Many factors can contribute to the poor health of a root system.

Cultural practices:

  • placing the plant in the ground too deeply
  • not digging a wide planting hole
  • digging the hole that is deeper than the root ball, resulting in settling of the plant
  • overwatering or underwatering
  • changing the grade around an established tree
  • poor care of the tree before planting
  • allowing plants to remain in a container too long, possibly leading to the formation of girdling or encircling roots
  • allowing turfgrass to grow around the base of the tree

Site factors:

  • poor drainage
  • poor soil (topsoil has been removed)
  • compacted soil
  • pH is too high for the species planted
  • not enough room for root expansion

Environmental conditions:

  • drought
  • excess moisture
  • temperature extremes

Healthy leaves and branches require a healthy root system to support vigorous growth. A poorly developed root system will not be able to absorb water and nutrients very well, causing stress symptoms above the ground. Keeping this in mind, remember to "look down" when diagnosing a plant problem. For more information on the proper planting of trees, refer to the Iowa State University bulletin, PM 1591 Community Tree Planting and Care Guide .

Bosnian pine roots

Poorly developed root system of a young pine tree planting in a compacted soil.
Girdling root

Formation of a girdling root around the base of a container-bound tree.

This article originally appeared in the 5/4/2005 issue.


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