[2] In Aotearoa New Zealand the Te Reo name is harore, the English vernacular name is olive honeycap, and the diseases caused by Armillaria species are called root rot.

[3][4][5] It was originally described as Armillariella novae-zelandiae by Greta Stevenson: "Pileus 3-8 cm diam., olive-buff to olive-brown, sprinkled at centre with very small dull brown scales, convex at first with a strongly down-rolled margin, becoming plane to shallow concave, moist when fresh with a conspicuously striate margin, drying matt; flesh creamy white.

Isolates from New Zealand and Australia are reciprocally monophyletic but considered conspecific by virtue of their similar basidiocarp morphology, vegetative growth characteristics and sexual compatibility.

Infected main roots develop a wet and pulpy rot, with white mycelial growth beneath the bark, and a distinctive 'mushroomy' smell.

In late stages of infection, the mycelial fan may advance up the lower trunk, causing swelling and cracking of the bark, and bleeding of a dark red exudate.

[2] Also, trees that have been weakened by stresses like defoliation by insects or frost, drought, waterlogging, soil compaction, air pollution, and foliage diseases.

[14] Burning of cleared pine plantation sites initially reduced rhizomorphs in the soil from 41-89% to 5-14% but levels soon recovered.

Removing and burning stumps reduced the mortality of young trees at age 5 from 52% to 12-21 %; however, this is very expensive and suitable for relatively flat terrain only.