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Field guide to exotic pests and diseases: Annosus root and butt rot
Heterobasidion annosum (Fr.:Fr.) Bref.
Annosus root and butt rot in white fir
Source: USDA Forest Service
Infected ponderosa pine stump and killed cedar saplings.
Source: USDA Forest Service
Distribution: USA, Canada, India, China and throughout Europe.
Hosts: wide host range, including gymnosperms and angiosperms.
Signs: leaves of young trees (especially pines) can turn brown and drop quickly with no prior indication of stress. Pines and other resinous trees can exude resin at butt. Resinous lesions develop on roots at points of attack and spread as pathogen grows toward butt. Trees with diseased roots may not show obvious signs above ground.
Fruiting bodies annual or perennial, woody to leathery: upper surface is dark brown to black with acute margin; lower surface white to cream. Fruiting bodies most often found on undersides of decayed roots of living and standing dead trees: readily produces conidia that are airborne; incipient stage of decay yellow-brown to red-brown; in advanced stage wood is reduced to a white stringy or spongy mass with many small black flecks parallel to grain.
Likely pathway: bark, lumber and wood packaging material including dunnage.
Potential impact: trees with major portion of root system killed show reduced leader and branch growth and foliage yellowing. Trees with extensive decay in structural roots subject to windthrow.