Armillaria root rot

Armillaria root rot
Armillaria fuscipes Petch

Armillaria heimii Pegler

Root rot

White thick mycelial mat under the bark of stems, white mycelial mat on roots, fruiting bodies at the stem base, dieback at advanced stage of disease, basal cankers with resin oozing from the stem.

Production of thick white mycelial mats, production of rhizomorphs (shoe string like structures) in culture and sometimes on the roots. During the sexual phase mushrooms are formed with caps up to 51 mm (average 35 mm) diam, convex later broadly plane, center broadly umbonate sometimes depressed encircling zone, citrine in the center, becomes orange yellow to shades of light cream at margin, brussels brown squamules are present on the cap, margin of cap incurved, striate. Lamellae: white, decurrent, close. Stipe: 64-87 mm X 2-4.5 mm, central, cylindrical, solid, olive gray becomes lighter towards the ring, buff coloured just above the ring, becomes citrine towards the apex, pale olive gray flocci are present from base to ring, brownish white inner tissue. Ring: close to apex, membranous saccate, circumscissile, whitish.    

1900s (as Armillaria mellea) (Pole Evans 1933, Kotzé 1935, Bottomley 1937)
KwaZulu-Natal, Limpopo, Mpumalanga
Africa (Coetzee et al. 2005 and reference therein)

Gallery

Armillaria fuscipes mushrooms
Armillaria fuscipes white mycelial mat under bark of dying pine
Basidiocarps of Armillaria fuscipes
Armillaria root rot

Bottomley AM. 1937. Some of the more important diseases affecting timber plantations in the Transvaal. South African Journal of Science 33: 373-6.

Coetzee MPA, Wingfield BD, Bloomer P, Wingfield MJ. 2005. Phylogenetic analyses of DNA sequences reveal species partitions amongst isolates of Armillaria from Africa. Mycological Research 109: 1223-1234.

Kotzé JJ. 1935. Forest fungi: The position in South Africa. Proceedings of the British Empire Forestry Conference, South Africa 12.

Pole Evans IB. 1933. Safeguarding the soil products of the Union. Farming South Africa 8: 486-93.