Heterobasidion annosum - Root Rot

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Polyporiales

Family: Bondarzewiaceae

One of the most serious parasites of conifers, Root Rotis the cause of major economic loss to the conifer forestry industry. Occasionally this root-rotting perennial bracket infects Beech trees and once in a while birches too.

The tough fruitbodies of Fomes Rot, as many forestry managers still call it (an earlier synonym for this species was Fomes annosus), occur low down on the buttress roots.

Trees become infected via wounds to the bark, where the sapwood of buttress roots is exposed. Stumps of freshly felled trees are an open invitation to this fungus, whose mycelium spreads from one tree to another where the roots of adjacent trees rub against one another.

Identification guide

Description	Brown, corrugated upper surface blackening with age; narrow, round-edged brackets; sometimes in tiers and occasionally resupinate; downy when young, then smooth but uneven or knobbly. Tubes: off-white; a new tube layer 2 to 5mm thick grows each year. Pores: creamy white; round; spaced at 2 to 4 per mm.
Size	The individual brackets are 5 to 30cm across and 1 to 2cm thick.
Spore print	Cream or pale yellow.
Odour/taste	Not distinctive.
Habitat	Parasitic on the lower trunks and buttress roots of conifers and very occasionally some hardwood trees.
Season	June to November.
Occurrence	Common.
Similar species	Gannoderma australe has a thicker fruitbody and releases brown spores.