News Article

For: Release week of August 5, 2002

To: Rotating Extension Column

By: Daniel E. Mullins - Extension Horticulture Agent

Santa Rosa County Extension Service

Telephone: 850-623-3868 or 939-1259, ext. 1360

Reducing the Incidence of Shade Tree Death

It would appear that something is going around, as an unusual number of dying shade and ornamental trees is being seen in local landscapes. Nothing is going around. Though dead and dying trees are more common this year, the condition cannot be blamed on an insect or disease epidemic.

This is little comfort to the homeowner who has lost a tree. This is however, a good time to evaluate what happened and prevent the loss of other trees.

The life span of an individual tree varies greatly depending upon the species and how well it is protected during property development. Some trees literally die of old age, but more often they die prematurely due to man made causes.

Root Damage and the “Delayed Reaction”

Though many trees tolerate property development, others die off over a long period of time as a result. Most frustrating for homeowners is the fact that large trees with extensive root damage can hang on for years before eventually dying.

This delayed reaction time between the time that root damage is done, and the time that symptoms appear is difficult to explain. It is equally difficult for a person with a dead tree on their hands to accept. Using a large live oak tree as an example here is what can, and often does, happen.

An established live oak under natural conditions has a root spread that is three times wider than the branch spread and most roots are within 12 inches of the soil surface.

This root system can be severely damaged in the following ways:

■ Filling with just a few inches of soil over the roots can result in

suffocation because oxygen levels are reduced.

■ A cut in grade that strips away natural leaf litter and removes surface

soil destroys many fine feeder roots.

■ Ditching for the installation of underground utility lines results in severed

roots.

■ Heavy equipment traveling over the root system compacts the soil and

breaks roots.

A live oak that has sustained damage due to one or more of the above causes begins to react immediately. First, it must tap its supply of stored food in order to compensate for a reduced root system.

Recovery from development will depend upon the severity of the root damage, how healthy the tree was when damaged and environmental conditions during the recovery period.

Several factors including root damage during development, species of trees involved and 4 years of drought have all contributed singly, and in combination.

Further complicating matters, the long drought has had a “weeding out” effect. Marginally healthy trees in both natural and residential areas have been most susceptible.

Unfortunately, by the time that the homeowner realizes that something is seriously wrong with the tree it is usually too late. When examining a root damaged tree several months or years after the fact we usually only see secondary insects and diseases that have moved in to take advantage of a weak plant.

Take heart in the fact that we are once again receiving summer rains. This extra soil moisture should help many trees to recover. Make plans to protect both the trunk and root system of each tree during future construction projects. Contact your local Extension office for information.

Dan Mullins is Extension Horticulture/Vegetable agent for Santa Rosa County.

Extension Service programs are open to all people without regard to race, color, sex, age, handicap or national origin. The use of trade names in this article is solely for the purpose of providing specific information. It is not a guarantee, warranty, or endorsement of the product name(s) and does not signify that they are approved to the exclusion of others.