blue spruce tree

Asked August 12, 2017, 12:48 PM EDT

from the trunk to almost the end of the branch. bare, and dropping brown dried up needles. What do have to do?? Its 30 foot tree.

Ramsey County Minnesota

3 Responses

Blue spruce are beautiful trees that are not well adapted to the midwest. There are any fungus and insects that weaken or kill this type of spruce tree. I am sending you links many sites that will help you diagnose the spruce decline. Examine the tree from the top of the leader to the base of the trunk. Look at which branches are bare. Examine the needles for signs of disease. Look for white sticky sap. Do you see any holes in the trunk or branches. The following are the two most common disease of blue spruce. Spruce trees infected with the Cytospora canker fungus typically show scattered branch dieback. A close look at the dead branches usually reveals the presence of sticky white sap. Infected trees produce this resinous sap in response to the infection by the canker fungus. Trees infected with Rhizosphaera needle cast fungus appear to die from the bottom upward. The lower branches are usually infected first and then Rhizosphaera works upward gradually. Second-year needles turn a purple or brown color and eventually fall from the tree. After several successive years of needle loss branches may die. In general, trees appear to die from the bottom upward. The following sites should be studied before you examine the tree.

so you did not tell me what I should do?? What can I do to save the tree. Would Sulphur
kill the fungus? Should I just cut it down?? My other tree has it also.

So far as we can tell from the photos, the tree is probably being damaged by Rhizosphaera . However, damage caused by some other fungal pathogens is indistinguishable from Rhizosphaera without laboratory analysis. With that caveat in mind, following are University of Minnesota recommendations regarding ways to contol Rhizosphaera:

  • Plant Norway or Black Hills spruce instead of Colorado blue spruce or Engelmann (P. engelmannii) spruce. Whenever possible plant spruce trees grown from local seed sources as these plants are likely to be best adapted to the local conditions.
  • Avoid planting young spruce near old spruce trees that may be harboring fungal pathogens.
  • Reduce stress on spruce trees by watering during periods of drought, mulching the soil around the tree, etc.
  • Do not allow lawn sprinklers to spray the spruce needles.
  • Space spruce trees to allow good air circulation around the trees.
  • Do not shear spruce as shearing creates a dense, compact growth that stays wet longer.
  • Chlorothalonil can be sprayed twice in the spring to protect new needles. The first spray should be applied when needles are half the length of the mature needles. A second spray should be applied 3-4 weeks later or as prescribed on the fungicide label. Read and follow all instructions on the label when applying a fungicide!
  • Before spraying fungicide, confirm that Rhizosphaera is the fungal pathogen causing damage by sending a lab sample to the University of Minnesota plant disease diagnostic clinic. Several other fungi result in symptoms very similar to Rhizosphaera.

It might be advisable to ask a forester or certified arborist to assess the trees' health onsite and recommend a course of action. This might include removing the trees instead of treating them. We can't make that determination by viewing the photos.