Tree Problems | Dutch Elm Disease

Tree Problems?

When tree problems are detected early and properly diagnosed, trees can often be saved from unnecessary loss. But an accurate diagnosis is not always easy, so you may need additional help from an experienced forester or arborist, or from a diagnostic laboratory. Fact sheets and Internet information about specific tree pests can help only after you have learned to consider all factors and take a logical, step-by-step approach.

Steps in Diagnosis

  • Be sure you have correctly identified your tree. For help, go to tree identifiction page.
  • Evaluate the appearance, or symptoms of the unhealthy tree. Urban trees are vulnerable to many stresses, caused by both living and non-living agents. Symptoms often overlap.
  • Look for direct evidence of the cause, such as bark beetle exit holes or a wire "girdling" the trunk.
  • Examine the tree systematically. Look closely at the leaves or needles, branches, trunk and roots.
  • Trees often show symptoms a year or more after damage has occurred, so consider the history of the tree. Homeowners who have lived in the neighborhood for a while can be very helpful in providing background information.
  • Sometimes even experts need laboratory assistance to confirm a tentative diagnosis.

Record Keeping
Two of the most useful diagnostic tools are a camera and a calendar. Pictures and notes of tree disorders and unusual weather occurrences taken one year will be valuable to refer to in the future.

Diagnotic Laboratories
University of Minnesota Plant Disease Clinic:

Minnesota Department of Agriculture Shade Tree Diagnostic Lab:  phone  (651) 296-4749

Additional Web Resources
The following links contain detailed information on hundreds of tree and forest pests, their significance and proper treatments.

Insects of trees manual:

Plant disease diagnostics :

Forest & tree health publications:

Dutch Elm Disease

The University of Minnesota has a one-stop web site for information on the diagnosis and treatment of Dutch Elm Disease, including:

  • Color photos of symptoms of Dutch Elm Disease
  • Where to have your elms tested for the disease
  • A history of Dutch Elm Disease
  • Suggested tree replacements
  • A downloadable brochure called “How to Identify and Manage Dutch Elm Disease,” published by the U.S. Forest Service.









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