Protecting your trees from insects and disease

Last September’s snowstorm damaged a significant portion of our trees. Damage or stress caused by the storm may make your trees more susceptible to disease or insects.

The yellow-headed spruce sawfly.

As well, this spring has been unusually dry, which can also compromise the health of your trees.

Jill-Anne Spence, urban forestry lead and Jim Watts, urban conservation technician, recently caught up with Global TV to explain how to look for pests and diagnose tree problems.

Watch the interview now.

Tips to diagnose tree health problems:

Inspect your tree. Early in the growing season you should inspect your trees for insects, disease or structural issues. Observe:

• The size of the leaves – are they growing properly?

• If the tree buds are properly sprouting.

• The annual growth of a branch.

• If the top of the tree, the crown, is growing.

Know your tree. Many insects and diseases are tree-specific so identifying the type of tree will set you in the right direction.  

Compare. Take a look at other trees around the same spot, especially those of the same species.  

Take a look at the roots, trunk, branches, and foliage. Discoloured roots and wounds on the branches or trunk could indicate a problem. Check foliage for discoloration or damage. This could indicate insect feeding or other issues.

Oystershell scale

Dutch elm disease (DED) is an important tree disease to be aware of in Calgary. There is a provincial pruning ban for elm trees from April 1 until September 30. It is important not to prune elm trees during this period because Alberta is one of the last areas in North America to be free of DED. We want to keep it that way!

Other pests to watch out for are: yellowheaded spruce sawfly; European elm scale; oystershell scale; and forest tent caterpillar.

For more information on healthy tree care, visit calgary.ca/trees.

Submitted by Althea Livingston, Parks