News release: Tree Decline in the Home Landscape, Part I

Tim Baker, MU Extension Horticulture Specialist
102 N. Main, Suite 1, Gallatin, MO 64640
660-663-3232, bakert@missouri.edu

Release Date: July 9, 2015

Headline: Tree Decline in the Home Landscape, Part I

Every year I receive many calls from homeowners about landscape trees that are dying.  Usually these are older trees which add much practical and esthetic value to the yard.  If a large tree such as this is lost, it will be many years before its replacement will attain this size.  Thus, the homeowner is willing to spend a lot of time, energy, and money to try to save the tree.

Sometimes these efforts can be successful.  But all too often, the tree is starting to die, and not much can be done to reverse the process.  When approaching an individual case, I first look for obvious symptoms of disease.  Sometimes a specific disease has attacked the tree, and if the tree is in otherwise good health, it may be treated and saved.  This is often the case with younger trees.  If no particular disease can be found, and if no apparent damage is seen, the tree is usually thought to be in “tree decline.”

“Tree decline” is a generic term which covers a multitude of problems.  Usually the problems are traceable to long-term environmental stress.  These stresses may allow secondary insects and diseases to attack the tree.  An example of environmental stress is a tree that is planted in an unsuitable location.  Trees have preferences for soil types, climates, sunlight requirements, and growing space.  If the tree is forced to grow in a less-than-optimal situation, stress will result, which over the long run may cause the tree to decline.

Other types of stress may include severe drought, flooding, construction damage, soil compaction, poor drainage, heavy insect infestations, structural damage, and similar problems.  Sometimes these problems can be treated or corrected, which will extend the life of your tree.

It’s best to take early corrective measures when these types of stresses are observed.

Often, secondary insects and diseases may invade trees under such stress.  Some wood boring insects provide an example.  Many of these insects attack only weak trees.  If the tree had been in good health, the insects would have gone elsewhere.  Even if you remove the insects, they will return, since the tree is in decline.  Another example is root diseases, a very common problem in our area.  Physiological changes occur in the roots of stressed trees which allow diseases to infect and kill them.  Healthy, non-stressed trees won’t have this problem.

In my next column, I will discuss some of the specific protective measures you can take to extend the life of your trees.