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
Description

Micro-habitat(s)

Trunk, Base of tree

Distribution

Canada

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

Photos
  • Armillaria ostoyae root disease Reduced leader growth and chlorotic foliage on Armillaria infected Douglas-fir
  • Armillaria ostoyae root disease Resinosus on the lower stem of an Armillaria infected tree
  • Armillaria ostoyae root disease Armillaria mycelial fans beneath bark of lower stem
  • Armillaria ostoyae root disease Armillaria mycelial fans beneath bark of lower stem
  • Armillaria ostoyae root disease Armillaria mycelial fans beneath bark of root
  • Armillaria ostoyae root disease Armillaria root disease centre in a 80- to 100-year-old Douglas-fir stand (30 years after partial cutting)
  • Armillaria ostoyae root disease Fruiting bodies of Armillaria ostoyae associated with Douglas-fir
  • Armillaria ostoyae root disease Fruiting bodies of Armillaria ostoyae associated with western larch
  • Armillaria ostoyae root disease Butt rot in Engelmann spruce
  • Armillaria ostoyae root disease Stump removal to reduce Armillaria inoculum
  • Armillaria ostoyae root disease Transfer of A. ostoyae from a colonized stump to a living tree in a spaced stand
  • Armillaria ostoyae root disease Armillaria fruiting bodies around a diseased Douglas-fir stump
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