Widely distributed in southern Australia, the fungus is responsible for a disease known as Armillaria root rot, a primary cause of Eucalyptus tree death and forest dieback.

The fruit bodies, which appear at the base of infected trees and other woody plants in autumn (March–April), are edible, but require cooking to remove the bitter taste.

The fungus is dispersed through spores produced on gills on the underside of the caps, and also by growing vegetatively through the root systems of host trees.

The ability of the fungus to spread vegetatively is facilitated by an aerating system that allows it to efficiently diffuse oxygen through rhizomorphs—rootlike structures made of dense masses of hyphae.

Armillaria luteobubalina was first described in 1978 by mycologists Roy Watling and Glen Kile, who studied its effects on a fast-growing plantation of Eucalyptus regnans near Traralgon, Victoria.

[1] For over one hundred years, A. mellea was thought to be a pleiomorphic (occurring in various distinct forms) species with a widespread distribution and host range, and variable pathogenicity.

[3] In 1973, Veikko Hintikka reported a technique to distinguish between Armillaria species by growing them together as single spore isolates on petri dishes and observing changes in the morphology of the cultures.

[5][6] Watling and Kile compared the macroscopic and microscopic characters of the pathogenic Armillaria with A. polymyces (now known as A. obscura), A. mellea, A. limonea and A. novae-zelandiae and found sufficient differences between them to warrant designating the species as new.

[9] Based on analysis of pectic enzymes, A. luteobubalina is closely related to A. limonea, a species found in New Zealand;[10] this result corroborates phylogenetic analyses reported in 2003[11] and 2006.

[13] Up to 10 cm (4 in) in diameter, the cap is convex to flattened in shape with a central umbo (a rounded elevation) and is various shades of cream, yellow and tan.

The crowded gills are sinuate and white to cream in colour initially, brownish-cream or pinkish brown in maturity, and sometimes with yellow or rust-coloured marks close to the margins.

The smooth spores are oval to ellipsoid, hyaline (translucent), non-amyloid (meaning they do not absorb iodine from Melzer's reagent), and typically measure 6.5–7.5 by 4.5–5.5 μm.

[19][22] The honey fungus infected and killed many plants near tuart trees (Eucalyptus gomphocephala) which had been cut down near Kings Park in suburban Perth.

[7] A 2003 study of the molecular phylogenetics and pattern of its distribution in South America and Australia indicate that A. luteobubalina is an ancient species, originating before the separation of the precursor supercontinent Gondwana.

Genetic differences between isolates in the South American and Australian populations indicate a long period of geographical separation, and the authors suggest that they "later might be regarded as independent taxa".

[25] A review of eucalypt plantations planted in New South Wales from 1994 to 2005 found that infection by A. luteobubalina was rare, and only accounted for 1% of mortality in total.

[25][27] Tree roots may be infected for years before showing above-ground symptoms, making it difficult to accurately assess the true extent of disease in a forest stand.

The study used more intensive surveying methods to determine that 25- to 30-year-old karri regrowth forests in western Australia showed an average of 40–45% incidence of infection.

[16] Several studies have shown that the spread of Armillaria root rot in eucalypt forests is associated with infected stumps that remain after an area has been logged.

[7] Armillaria luteobubalina uses "an elaborate, sophisticated aeration system" that enables it to efficiently deliver oxygen into the rhizomorphs, helping it thrive in low-oxygen environments.

[42] These methods are often not practical due to high cost, introduction of toxic chemicals that affect other organisms, or health and safety issues for the operator.