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Dutch Elm Disease

Dutch Elm Disease (DED) is a fungal disease spread by tiny elm bark beetles that breed under the bark of dead or dying elm wood.

Provincial Pruning Ban

In an effort to help curb the spread of DED, the Province issues an annual ban on pruning elm trees in Saskatchewan from April 1 until August 31. During this period, it is illegal to prune elm trees.

The ban occurs at the time of year when the elm bark beetles that spread DED are most active. Fresh cuts from trimming trees can attract the tiny insects, increasing the chance of an infection.

Symptoms of DED

  • Early season (June) symptoms include green wilted leaves.
  • As the disease progresses the leaves turn yellow and then brown and curled.
  • As the fungus grows and spreads within the vascular tissue of the tree, the wilting symptoms continue to spread throughout the canopy.
  • The tree may also shed its leaves prematurely or if infected the previous year, may not flush out leaves at all the following season.
  • The vascular tissue of a DED infected elm tree, when viewed in cross-section, may have brown staining within it.

DED Prevention

  • Prune dead, dying and rubbing branches to remove elm bark beetle habitat outside the pruning ban period of April 1 to August 31. Be sure to dispose of pruned branches by either burning or burying the wood to a minimum depth of 20 centimeters of top soil.
  • Water the tree during drought periods and avoid mechanical damage to the roots, trunk and branches of the tree.
  • Regularly monitor your elm trees for symptoms of DED.
  • Elm bark beetle basal spraying using insecticides has been known to be effective for beetle population management. This work must be completed by a licensed pesticide applicator.

For more DED information visit the Government of Saskatchewan website.