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Armillaria ostoyae root disease

Armillaria ostoyae root disease - Fruiting bodies of <em>Armillaria ostoyae</em> associated with Douglas-fir
  • Latin name: Armillaria ostoyae (Romagnesi) Herink
  • French name: Pourridié-agaric à Armillaria ostoyae
  • Division: Basidiomycota
  • Class: Agaricales


Trunk, Base of tree



Damage, symptoms and biology

Armillaria ostoyae causes growth loss and small amounts of butt rot in diseased trees, however mortality is the greatest cause of loss. The fungus can kill conifers in plantations and natural stands throughout a rotation when roots of healthy trees grow into contact with, or form root grafts with the roots of diseased trees.

Losses due to decay caused by this fungus are always higher in conifers than in hardwoods.

Other information

On sites infested by A. ostoyae, there are currently two management strategies that can be applied at the time of harvest to reduce losses in the next rotation:

  1. reduce the amount of inoculum by removing stumps, and
  2. regenerate the site with one or more resistant or poor-host species.

Canadian Forest Service Publications

Armillaria ostoyae root disease

Information on host(s)

Main host(s)

Amabilis fir, Austrian pine, balsam fir, black spruce, eastern white pine, Engelmann spruce, European larch, grand fir, jack pine, Jananese larch, Lawson-cypress, mugho pine, Norway spruce, ponderosa pine, red pine, Rocky Mountain Douglas-fir, Rocky Mountain juniper, scots pine, shore pine, Sitka spruce, subalpine fir, sugar maple, western hemlock, western larch, western redcedar, western white pine, western yew, white spruce

Secondary host(s)

Balsam poplar, grey birch, silver maple, trembling aspen, white birch, white elm, yellow birch


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