Armillaria ostoyae root disease
- French disease name: Pourridié-agaric à Armillaria ostoyae
- Pathogen name: Armillaria ostoyae (Romagnesi) Herink
- Kingdom: Fungi
- Phylum: Basidiomycota
- Class: Agaricomycetes
- Order: Agaricales
- Family: Physalacriaceae
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:
- reduce the amount of inoculum by removing stumps, and
- 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, mugo 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
Reduced leader growth and chlorotic foliage on Armillaria infected Douglas-fir
Duncan Morrison
Resinosus on the lower stem of an Armillaria infected tree
Duncan Morrison
Armillaria mycelial fans beneath bark of lower stem
Duncan Morrison
Armillaria mycelial fans beneath bark of lower stem
Duncan Morrison
Armillaria mycelial fans beneath bark of root
Duncan Morrison
Armillaria root disease centre in a 80- to 100-year-old Douglas-fir stand (30 years after partial cutting)
Duncan Morrison
Fruiting bodies of Armillaria ostoyae associated with Douglas-fir
Duncan Morrison
Fruiting bodies of Armillaria ostoyae associated with western larch
Duncan Morrison
Butt rot in Engelmann spruce
Duncan Morrison
Stump removal to reduce Armillaria inoculum
Duncan Morrison
Transfer of A. ostoyae from a colonized stump to a living tree in a spaced stand
Armillaria fruiting bodies around a diseased Douglas-fir stump
Rona Sturrock