Honey Fungus (Armillaria Mellea)


Common host(s)                   Wide range, more common on broadleaves

Colonisation strategy           Sheets of white mycelium. Rhizomorphs can travel tens of metres through soil. Usually in top 25-30 cm of soil, enter roots and travel up into inner bark (phloem) to feed on sugars. Old stumps build up colonies of fungus. Endemic in the UK, Europe and US

Symptoms                            Mushroom-shaped fruiting bodies, honey coloured. Relatively short lived at base of infected trees/stumps. Seen especially in moist seasons. Sheets of bark fall away at base to reveal white mycelium, fan-shaped, mushroom smell. Sometimes black (bootlace) rhizomorphs with a reddish hue. Excessive flowering/fruiting may accompany crown decline, especially in hot dry seasons.

Type of rot                           White root rot and butt rot, sometimes with visible black pseudoscleratial plates. Heartwood or sapwood.

Part(s) of tree affected         Stem base, roots.

Significance                           Uprooting or occasionally stem fracture. Death of small trees usually in a year or 2. Longer in larger trees but if infection is complete then death is likely. Bark dies at the base of the tree, roots rot and crown gradually recedes. No cure. Physical barrier may stop spread of rhizomorphs. Remove or grind old stumps as the fungus needs living or dead wood as a host.

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