Armillaria Root disease in Calgary

Armillaria Root rot or Armillaria Root disease are common names for several fungi in the Armillaria family. The disease can infect a wide variety of tree species; In Calgary we often see this in old hollow Apple trees, but as said almost any tree can be infected.

Armillaria Root disease is commonly identified by white rotting fungi and mushrooms at the base of the trunk. The disease can infect trees through release of spores, but most infections happen by roots of different trees touching each other, enabling the fungus to grow into the new host.

Trees affected by Armillaria Root disease

Which of my trees should be inspected for Armillaria Root disease?

Armillaria Root disease can affect almost any tree species, although some are more susceptible than others. Common trees to get Armillaria Root disease are:

  • (Crab) Apple trees,
  • Mountain Ash trees,
  • Spruce trees
  • Pine trees

Is my tree infected with Armillaria Root disease?

Common symptoms linked to Armillaria Root disease are

  • Mycelial fans (white mats of fungus over infected parts)
  • Mushroom odor when scratching infected parts
  • Rhizomorphs (mycelial strings) on infected parts
  • Mushrooms (mainly near the base of the tree)
  • Branches dying
  • General unhealthy look

Following pictures can help you determine if your tree is infected with Armillaria Root disease.

Armillaria Mellea Root Disease mushrooms

Mushrooms on base of trunk of European Beech. Andrej Kunca, National Forest Centre – Slovakia,

Armillaria Mellea Root Disease Mycelial fans

Mycelial fans. Edward L. Barnard, Florida Department of Agriculture and Consumer Services,


Can Armillaria Root disease be treated?

There are several measures that can be taken to control the affects of Armillaria Root disease.

Mechanical measures:

Chemical control:

  • Fungicide application, through trunk injection methods.

Is my tree infected?

Call your certified arborist for a professional diagnosis and a proper treatment plan.