Wednesday, January 9, 2008

Landscape - Tree Problems

The following are some common problems that we see with trees in the landscape, what they mean, and what to do about them.

Several signs can help pinpoint tree problems while they are still treatable.

Root Flare

Does the tree enter the ground with a natural flare or swelling? No flare may mean soil has been filled around the tree and roots are suffocating. No flare may also mean there is a girdling root restricting food, nutrients, and water.

Crown Dieback

Search for dead twigs or branches dying back from the tips to the trunk in the tree crown. Dead twigs and branches may mean old age, insect or disease infestation, or root injury. Crown dieback may indicate too much or too little moisture, or too much competition.

Abnormal Leaf Size

A tree that has leaves smaller than the normal size may have a root injury. Leaves that are larger than normal, especially on root suckers, can also indicate root damage.

Trunk Scars

Partially “healed” wounds on trunks may be signs of hidden decay. Look for ragged scars on the trunk that are not callused over. To speed callusing, remove damaged, ragged tissue carefully with a sharp knife. Coating wounds with preparations has not been proven to promote healing, and coatings can trap water and provide habitat for insects and diseases that cause damage and decay.

Disruption of Root System

Root systems grow primarily in the top 3 feet of soil; the small absorbing roots are mostly in the top 6 inches. The roots are easy to damage. Sidewalks and streets paved over roots can severely compact the soils around fine roots. Trenches cut to install underground utility lines can remove all roots alongside of a tree. The impact of such root damage may not show up in the tree crown for two to five years.

Yellow Foliage

The general yellowing of a leaf, often called chlorosis, can be caused by a variety of factors, including insects, disease, too much moisture, cold weather, air and soil pollution, excess minerals in the soil, nutrient deficiencies, or a pH imbalance.

Sticky Substance Dripping From the Tree

Insect honeydew is usually the waste product of insects such as aphids, lace bugs, or scale. While this aggravating problem can be controlled with insecticides, insects causing the honeydew seldom harm the health of the tree.


Large populations of insects may or may not damage a tree. Inspect your trees on a regular basis. Look for signs of reduced tree health. Some adult insect populations last only a few days and some can last for eight weeks. An impulsive control measure will destroy the natural predators that could control the pest without any intervention. If you suspect an insect pest, collect the pest and the symptoms and take them to your local Cooperative Extension office for identification and control recommendations.

Reprinted from the publication "Trees for Delaware" From the University of Delaware Cooperative Extension.

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