Heterobasidion annosum

(Fr.) Bref.

Multiple brackets at the base of a senescent hawthorn at Burnham Beeches, Buckinghamshire.
Maturing brackets with water exudations growing on a sawn pine log in Langdon Hills, Essex
Sporulating brackets on a larch stump along the River Great Ouse, Bedfordshire
The complex pore layer beneath with its off-white colouration
Developing pore layer with mottled appearance on hawthorn at Burnham Beeches, Buckinghamshire

Multiple brackets at the base of a senescent hawthorn at Burnham Beeches, Buckinghamshire.
Maturing brackets with water exudations growing on a sawn pine log in Langdon Hills, Essex
Sporulating brackets on a larch stump along the River Great Ouse, Bedfordshire
The complex pore layer beneath with its off-white colouration
Developing pore layer with mottled appearance on hawthorn at Burnham Beeches, Buckinghamshire
Mature brackets on a larch stump in Bedford, UK.
Very young resupinate fruit bodies on a veteran pine at Hampstead Heath, UK.
Young and resupinate fruit bodies on a pine log in Laindon, UK.
The shiny-when-wet upper surface of brackets.
A very dark but still active fruit body on a conifer stump in Sweden.

Common name

Conifer butt rot; conifer root rot; Fomes root rot

Often found on

Fir, larch, pine, spruce, and other conifers.

Sometimes found on

Beech, hawthorn, and more rarely other broadleaved species.

Location

Found at the base of the host tree and on buttress roots. Also found on stumps.

Description

Perennial. Tough and woody. Usually an undulating reddish-brown top (can blacken with age or become algal-stained) with a near-white pore layer that bruises a soft skin pink. Underside can exude water droplets. Surface glistens when wet. Cream white spore. White flesh. Sometimes rimmed white. Considered a species complex.

Confused with

Fomitopsis pinicola; Ganoderma australe (brown spore).

Significance

Attributed with a selective white rot of wood that eventually causes cavity formation. Parasitic upon living trees – can propagate via root-to-root contact. When found on trees with targets beneath / in falling distance, investigations into the stability of the tree may be required. Entire removal (including of the stump) may be needed, where biosecurity measures are paramount (commercial forestry).