Armillaria ostoyae

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Armillaria ostoyae
Armillaria ostoyae.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Physalacriaceae
Genus: Armillaria
Species:
A. ostoyae
Binomial name
Armillaria ostoyae
(Romagnesi) Herink (1973)
Synonyms
  • Agaricus congregatusBolton 1791 nom. illeg.
  • Armillaria mellea var. obscuraGillet 1874
  • Armillariella ostoyaeRomagn. 1970 nom. cons.
  • Armillaria solidipesPeck 1900 nom. rej.
Armillaria ostoyae
Information icon.svg
Gills icon.png Gills on hymenium
Campanulate cap icon.svgConvex cap icon.svg Cap is campanulate or convex
Decurrent gills icon2.svg Hymenium is decurrent
Ring stipe icon.svg Stipe has a ring
Transparent spore print icon.svg
 Spore print is white
Parasitic fungus.svgEcology is parasitic
Mycomorphbox Choice.pngEdibility is choice

Armillaria ostoyae (synonym Armillaria solidipes) is a species of fungus (mushroom), pathogenic to trees, in the family Physalacriaceae. In the western United States, it is the most common variant of the group of species under the name Armillaria mellea . A. ostoyae is common on both hardwood and conifer wood in forests west of the Cascade Range in Oregon, United States. It has decurrent gills and the stipe has a ring. [1] The mycelium invades the sapwood and is able to disseminate over great distances under the bark or between trees in the form of black rhizomorphs ("shoestrings"). [2] In most areas of North America, Armillaria ostoyae can be separated from other species by its physical features: cream-brown colors, prominent cap scales, and a well-developed stem ring distinguish it from other Armillaria. Like several other Armillaria, the mycelium of Armillaria ostoyae can display bioluminescence, resulting in foxfire. [3]

Contents

Armillaria ostoyae grows and spreads primarily underground, such that the bulk of the organism is not visible from the surface. In the autumn, the subterranean parts of the organism bloom "honey mushrooms" as surface fruits. [2] Low competition for land and nutrients often allow this fungus to grow to huge proportions, and it possibly covers more total geographical area than any other single living organism. [2] [4] [5] A spatial genetic analysis estimated that an individual specimen of A. ostoyae growing over 91 acres (37 ha) in northern Michigan, United States, weighs 440 tons (4 x 105 kg). [6] [7]

Another specimen in northeastern Oregon's Malheur National Forest is possibly the largest living organism on Earth by mass, area, and volume – this contiguous specimen covers 3.7 square miles (2,400 acres; 9.6 km2) and is colloquially called the "Humongous fungus". [2] Approximations of the land area occupied by the "Humongous fungus" are 3.5 square miles (9.1 km2) (2,240 acres (910 ha)), and it possibly weighs as much as 35,000 tons (approximately 31,500 tonnes), making it the world's most massive living organism. [8]

Taxonomy

Armillaria ostoyae Armillaria ostoyae MO.jpg
Armillaria ostoyae

The species was long known as Armillaria ostoyae Romagn., until a 2008 publication revealed that the species had been described under the earlier name Armillaria solidipes by Charles Horton Peck in 1900, [9] long before Henri Romagnesi had described it in 1970. [10] Subsequently, a proposal to conserve the name Armillaria ostoyae was published in 2011 and has been approved by the Nomenclature Committee for Fungi. [11]

Life cycle, genetics, and mass

This fungus, like most parasitic fungi, reproduces sexually. The fungi begin life as spores, released into the environment by a mature mushroom. Armillaria ostoyae has a white spore print. There are two mating types for spores (not male and female but similar in effect). Spores can be dispersed by environmental factors such as wind, or they can be redeposited by an animal. Once the spores are in a resting state, the single spore must come in contact with a spore of a complementary mating type and of the same species. If the single spore isolates are from different species, the colonies will not fuse together and they will remain separate. When two isolates of the same species but different mating types fuse together, they soon form coalesced colonies which become dark brown and flat. With this particular fungus it will produce mycelial cords – the shoestrings [2] – also known as rhizomorphs. [12] These rhizomorphs allow the fungus to obtain nutrients over distances. These are also the main factors to its pathogenicity. As the fruiting body continues to grow and obtain nutrients, it forms into a mature mushroom. Armillaria ostoyae in particular grows wide and thin sheet-like plates radiating from the stem which is known as its gills. The gills hold the spores of a mature mushroom. This is stained white when seen as a spore print. Once spore formation is complete, this signifies a mature mushroom and now is able to spread its spores to start a new generation.

Genetics and mass

Using genotyping and clonal analysis, scientists determined that a 2500-year old specimen of Armillaria ostoyae in northern Michigan, United States originated from spores of a parent fungus in Ontario, Canada, then grew over millennia into the 21st century to a mass of 440 tons (4 x 105 kg), making it the equivalent in weight of 3 blue whales. [6] [7] By comparison of acreage, the Michigan A. ostoyae covers only 38% of the estimated land area of the Oregon "humongous fungus" at 3.5 square miles (9.1 km2), [2] [6] [7] (2,240 acres (910 ha) which may weigh as much as 35,000 tons. It is currently the world's largest single living organism. [8] [13] [14]

Pathogenicity

The disease is of particular interest to forest managers, as the species is highly pathogenic to a number of commercial softwoods, notably Douglas-fir (Pseudotsuga menziesii), true firs (Abies spp.), pine trees ( Pinus ), and Western Hemlock (Tsuga heterophylla). [8] A commonly prescribed treatment is the clear cutting of an infected stand followed by planting with more resistant species such as Western redcedar (Thuja plicata) or deciduous seedlings.

Pathogenicity is seen to differ among trees of varying age and location. Younger conifer trees at age 10 and below are more susceptible to infection leading to mortality, with an increased chance of survival against the fungus where mortality can become rare by age 20. [15] While mortality among older conifers is less likely to occur, this does happen, however, in forests with dryer climates. [16]

The pathogenicity of Armillaria ostoyae appears to be more common in interior stands, but its virulence is seen to be greater in coastal conifers. Although conifers along the coastal regions show a lower rate of mortality against the root disease, infections can be much worse. Despite differences in how infections occur between these two regions, infections are generally established by rhizomorph strands, and pathogenicity is correlated to rhizomorph production.

Geography

Armillaria ostoyae is mostly common in the cooler regions of the northern hemisphere. In North America, this fungus is found on host coniferous trees in the forests of British Columbia and the Pacific Northwest. [2] It also grows in parts of Asia. [1] While Armillaria ostoyae is distributed throughout the different biogeoclimatic zones of British Columbia, the root disease causes the greatest problem in the interior parts of the region in the Interior Cedar Hemlock biogeoclimatic zone. [17] It is both present in the interior where it is more common as well as along the coast.

A mushroom of this type in the Malheur National Forest in the Strawberry Mountains of eastern Oregon, was found to be the largest fungal colony in the world, spanning an area of 3.5 square miles (2,200 acres; 9.1 km2). [2] [8] This organism is estimated to be some 8,000 years old [8] [18] and may weigh as much as 35,000 tons. [8] If this colony is considered a single organism, it is one of the largest known organisms in the world by area, only knowingly rivalled by a colony of Posidonia australis on the Australian seabed that measures 200 square kilometres (77 sq mi; 49,000 acres), and rivals the aspen grove "Pando" as the known organism with the highest living biomass. Another "humongous fungus" – a specimen of Armillaria gallica found at a site near Crystal Falls, Michigan – covers 91 acres (0.37 km2; 0.142 sq mi), was found to have originated from a parent fungus in Ontario, Canada. [6] [19]

Diagnosis

A tree is diagnosed with this parasitic fungus once the following characteristics are identified:

A. ostoyae may be confused with Mottled rot ( Pholiota limonella ). It has similar mushrooms, but only if mycelial fans are not present. Dead and diseased trees usually occur in disease centers, which appear as openings in the canopy. GPS tracking can aid in the monitoring of these areas. However, sometimes distinct centers will be absent and diseased trees are scattered throughout the stand. [20]

Treatment

Armillaria can remain viable in stumps for 50 years. Chemical treatments do not eradicate the fungus entirely, and they are not cost-effective. The most frequent and effective approach to managing root disease problems is to attempt to control them at final harvest by replanting site-suited tree species that are disease tolerant. In eastern Washington that typically means replacing Douglas-fir or true fir stands with ponderosa pine, western larch, western white pine, lodgepole pine, western red cedar, alder, or spruce. Species susceptibility varies somewhat from location to location. All trees in the disease center as well as uninfected trees within 50 feet (15 m) should be cut. No tree from a highly susceptible species should be planted within 100 feet (30 m) of a disease center.

The use of another fungus, Hypholoma fasciculare has been shown in early experiments to competitively exclude Armillaria ostoyae in both field and laboratory conditions, but further experimentation is required to establish the efficacy of this treatment.

Another more expensive alternative to changing species is to remove diseased stumps and trees from the site by pushing them out with a bulldozer. The air will dry and kill the fungus. Any small roots left underground will decay before they can reinfect the new seedlings, so it is not necessary to burn the stumps. After stump removal, any species may be planted. The removal of stumps (stumping) has been used to prevent contact between infected stumps and newer growth resulting in lower infection rates. It is unknown if the lower infection rates will persist as roots of young trees extend closer to the original inoculate from the preceding stand.

The most important control measure after planting is to manage for reduced tree stress. This includes regulating species composition, maintaining biological diversity, and reducing the chances for insect pest buildup. Mixed-species forests are more resistant to insect defoliation, and also slow the spread of species-specific pests such as dwarf mistletoe, which are both predisposing agents for Armillaria. [21]

Uses

The species is considered a choice edible. [22]

See also

Related Research Articles

<i>Armillaria</i> Genus of fungi

Armillaria is a genus of fungi that includes the A. mellea species known as honey fungi that live on trees and woody shrubs. It includes about 10 species formerly categorized summarily as A. mellea. Armillarias are long-lived and form the largest living fungi in the world. The largest known organism covers more than 3.4 square miles (8.8 km2) in Oregon's Malheur National Forest and is estimated to be 2,500 years old. Some species of Armillaria display bioluminescence, resulting in foxfire.

<i>Armillaria mellea</i> Species of fungus

Armillaria mellea, commonly known as honey fungus, is an edible basidiomycete fungus in the genus Armillaria. It is a plant pathogen and part of a cryptic species complex of closely related and morphologically similar species. It causes Armillaria root rot in many plant species and produces mushrooms around the base of trees it has infected. The symptoms of infection appear in the crowns of infected trees as discoloured foliage, reduced growth, dieback of the branches and death. The mushrooms are edible but some people may be intolerant to them. This species is capable of producing light via bioluminescence in its mycelium.

Humongous Fungus may refer to:

<span class="mw-page-title-main">Malheur National Forest</span> National forest in Oregon, United States

The Malheur National Forest is a National Forest in the U.S. state of Oregon. It contains more than 1.4 million acres (5,700 km2) in the Blue Mountains of eastern Oregon. The forest consists of high desert grasslands, sage, juniper, pine, fir, and other tree species. Elevations vary from about 4,000 feet (1,200 m) to the 9,038-foot (2,755 m) peak of Strawberry Mountain. The Strawberry Mountains extend east to west through the center of the forest. U.S. Route 395 runs south to north through the forest, while U.S. Route 26 runs east to west.

<i>Hypholoma fasciculare</i> Species of fungus

Hypholoma fasciculare, commonly known as the sulphur tuft or clustered woodlover, is a common woodland mushroom, often in evidence when hardly any other mushrooms are to be found. This saprotrophic small gill fungus grows prolifically in large clumps on stumps, dead roots or rotting trunks of broadleaved trees.

<span class="mw-page-title-main">Mycelial cord</span> Structure produced by fungi

Mycelial cords are linear aggregations of parallel-oriented hyphae. The mature cords are composed of wide, empty vessel hyphae surrounded by narrower sheathing hyphae. Cords may look similar to plant roots, and also frequently have similar functions; hence they are also called rhizomorphs. As well as growing underground or on the surface of trees and other plants, some fungi make mycelial cords which hang in the air from vegetation.

<i>Armillaria luteobubalina</i> Species of fungus in the family Physalacriaceae.

Armillaria luteobubalina, commonly known as the Australian honey fungus, is a species of mushroom in the family Physalacriaceae. 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. It is the most pathogenic and widespread of the six Armillaria species found in Australia. The fungus has also been collected in Argentina and Chile. Fruit bodies have cream- to tan-coloured caps that grow up to 10 cm (4 in) in diameter and stems that measure up to 20 cm (8 in) long by 1.5 cm (1 in) thick. 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.

<i>Armillaria tabescens</i> Species of fungus

Armillaria tabescens is a species of fungus in the family Physalacriaceae. It is a plant pathogen. The mycelium of the fungus is bioluminescent.

<i>Heterobasidion annosum</i> Species of fungus

Heterobasidion annosum is a basidiomycete fungus in the family Bondarzewiaceae. It is considered to be the most economically important forest pathogen in the Northern Hemisphere. Heterobasidion annosum is widespread in forests in the United States and is responsible for the loss of one billion U.S. dollars annually. This fungus has been known by many different names. First described by Fries in 1821, it was known by the name Polyporus annosum. Later, it was found to be linked to conifer disease by Robert Hartig in 1874, and was renamed Fomes annosus by H. Karsten. Its current name of Heterobasidion annosum was given by Brefeld in 1888. Heterobasidion annosum causes one of the most destructive diseases of conifers. The disease caused by the fungus is named annosus root rot.

<i>Armillaria fuscipes</i> Species of fungus

Armillaria fuscipes is a plant pathogen that causes Armillaria root rot on Pinus, coffee plants, tea and various hardwood trees. It is common in South Africa. The mycelium of the fungus is bioluminescent.

<span class="mw-page-title-main">Largest organisms</span>

This article lists the largest organisms for various types of life and mostly considers extant species, which found on Earth can be determined according to various aspects of an organism's size, such as: mass, volume, area, length, height, or even genome size. Some organisms group together to form a superorganism, but such are not classed as single large organisms. The Great Barrier Reef is the world's largest structure composed of living entities, stretching 2,000 km (1,200 mi), but contains many organisms of many types of species.

<i>Rhizina undulata</i> Species of fungus

Rhizina undulata, commonly known as the doughnut fungus or the pine firefungus, is a species of fungus in the family Rhizinaceae. The fruit bodies of the fungus are dark purple brown with a bright yellow margin, crust-like and attached to the growing surface by numerous root-like yellow rhizoids. R. undulata has a cosmopolitan distribution, and commonly occurs on clearings or burned areas throughout central and northern Europe, North America, northern Asia, and southern Africa. It is parasitic on conifer seedlings, and has caused considerable damage to tree plantations worldwide.

<i>Armillaria novae-zelandiae</i> Species of fungus

Armillaria novae-zelandiae is a species of mushroom-forming fungus in the family Physalacriaceae. This plant pathogen species is one of three Armillaria species that have been identified in New Zealand.

<i>Armillaria gallica</i> Species of fungus in the family Physalacriaceae

Armillaria gallica is a species of honey mushroom in the family Physalacriaceae of the order Agaricales. The species is a common and ecologically important wood-decay fungus that can live as a saprobe, or as an opportunistic parasite in weakened tree hosts to cause root or butt rot. It is found in temperate regions of Asia, North America, and Europe. The species forms fruit bodies singly or in groups in soil or rotting wood. The fungus has been inadvertently introduced to South Africa. Armillaria gallica has had a confusing taxonomy, due in part to historical difficulties encountered in distinguishing between similar Armillaria species. The fungus received international attention in the early 1990s when an individual colony living in a Michigan forest was reported to cover an area of 15 hectares, weigh at least 9.5 tonnes, and be 1,500 years old. This individual is popularly known as the "humongous fungus", and is a tourist attraction and inspiration for an annual mushroom-themed festival in Crystal Falls. Recent studies have revised the fungus's age to 2,500 years and its size to about 400 tonnes, four times the original estimate.

<i>Armillaria nabsnona</i> Species of fungus

Armillaria nabsnona is a species of fungus in the family Physalacriaceae. The species is found in the west coast of North America, Hawaii, and Japan, where it grows on decaying hardwoods, particularly species of alder. Its fruit bodies have convex to flattened orange-brown caps up to 7 cm in diameter, brown stipes, and whitish to pinkish-tan gills.

<i>Armillaria</i> root rot Fungal tree disease

Armillaria root rot is a fungal root rot caused by several different members of the genus Armillaria. The symptoms are variable depending on the host infected, ranging from stunted leaves to chlorotic needles and dieback of twigs and branches. However, all infected hosts display symptoms characteristic of being infected by a white rotting fungus. The most effective ways of management focus on limiting the spread of the fungus, planting resistant species, and removing infected material. This disease poses a threat to the lumber industry as well as affecting recreational areas.

Armillaria altimontana is a species of agaric fungus in the family Physalacriaceae. The species, found in the Pacific Northwest region of North America, was officially described as new to science in 2012. It was previously known as North American biological species (NABS) X. It grows in high-elevation mesic habitats in dry coniferous forests. This species has been found on hardwoods and conifers and is associated most commonly with fir-dominated forest types in southern British Columbia, Washington, Oregon, Idaho and northern California.

<i>Heterobasidion occidentale</i> Species of fungus

Heterobasidion occidentale is a tree root-rotting pathogenic fungus in the family Bondarzewiaceae. It is endemic in western North America west of the Rocky Mountains from Alaska to southern Mexico. While a natural agent of forest turnover, H. occidentale has become of increased concern due to forest management processes such as pre-commercial thinning, altered site density and species composition, and carbon sequestration. H. occidentale forms part of the genus that includes other species forming the important forest pest Heterobasidion annosumsensu lato that is spread across the Northern Hemisphere. H. occidentale is part of the S-type intersterility group differing from the other North American species, Heterobasidion irregulare.

<i>Rhizomorpha</i> Genus of fungi

Rhizomorpha is a genus of fungi that was created for species known only by their mycelial cords ("rhizomorphs") and so impossible to classify within the normal taxonomic system, which is based on reproductive structures.

References

  1. 1 2 "Armillaria ostoyae, Dark Honey Fungus". first-nature.com. Retrieved 23 October 2019.
  2. 1 2 3 4 5 6 7 8 Schmitt CL, Tatum ML (2008). "The Malheur National Forest: Location of the world's largest living organism (the Humongous Fungus)" (PDF). Forest Service, US Department of Agriculture. Archived from the original (PDF) on 3 August 2019. Retrieved 16 December 2018.
  3. ↑ Rishbeth J. (1986). "Some characteristics of English Armillaria species in culture". Transactions of the British Mycological Society. 86 (2): 213–218. doi:10.1016/S0007-1536(86)80147-4.
  4. ↑ "Biggest living thing". Extreme Science. 1 December 2010.
  5. ↑ Puiu, Tibi (6 February 2015). "The largest organism in the world". ZME Science. Retrieved 20 February 2015.
  6. 1 2 3 4 Anderson, James B.; Bruhn, Johann N.; Kasimer, Dahlia; Wang, Hao; Rodrigue, Nicolas; Smith, Myron L. (26 July 2018), "Clonal evolution and genome stability in a 2,500-year-old fungal individual", bioRxiv, Cold Spring Harbor Laboratory: 377234, doi: 10.1101/377234
  7. 1 2 3 Jason Daley (15 October 2018). "This humongous fungus is as massive as three blue whales: A new estimate suggests this mushroom is 2,500 years old and weighs 440 tons". Smithsonian.com. Retrieved 23 September 2019.
  8. 1 2 3 4 5 6 Vince Patton (12 February 2015). "Oregon Humongous Fungus Sets Record As Largest Single Living Organism on Earth (7-minute documentary video)". Oregon Field Guide. Retrieved 23 September 2019.
  9. ↑ Peck, C. H. (1900). "New species of Fungi". Bulletin of the Torrey Botanical Club. 27 (12): 609–613. doi:10.2307/2477998. JSTOR   2477998.
  10. ↑ Burdsall, H. H.; Volk, T. J. (2008). "Armillaria solidipes, an older name for the fungus called Armillaria ostoyae" (PDF). North American Fungi. 3 (7): 261–267. doi:10.2509/naf2008.003.00717. Archived from the original (PDF) on 21 July 2011.
  11. ↑ Redhead, S. A.; Bérubé, J.; Cleary, M. R.; Holdenrieder, O.; Hunt, R. S.; Korhonen, K. R.; Marxmüller, H.; Morrison, D. J. (2011). "(2033) Proposal to conserve Armillariella ostoyae (Armillaria ostoyae) against Agaricus obscurus, Agaricus occultans, and Armillaria solidipes (Basidiomycota)". Taxon. 60 (6): 1770–1771. doi: 10.1002/tax.606023 .
  12. ↑ Korhonen, K. (1978). "Interfertility and Clonal Size in Armillaria mellea Complex". Karstenia. 18: 31–42. doi: 10.29203/ka.1978.135 .
  13. ↑ "The Malheur National Forest Location of the World's Largest Living Organism [The Humongous Fungus]" (PDF). fs.usda.gov. 2008. Archived (PDF) from the original on 24 March 2012. Retrieved 1 August 2021.
  14. ↑ "Oregon Humongous Fungus Sets Record As Largest Single Living Organism On Earth". opb. Retrieved 1 August 2021.
  15. ↑ Morrison, D. J.; Pellow, K. W. (2002). "Variation in Virulence Among Isolates of Armillaria ostoyae". Forest Pathology. 32 (2): 99–107. doi:10.1046/j.1439-0329.2002.00275.x.
  16. ↑ Harington, T. C.; Wingfield, M. J. (2000). "19. Diseases and the Ecology of Indigenous and Exotic Pines". In Richardson, D. M. (ed.). Ecology and Biogeography of Pinus. Cambridge University Press. p. 386. ISBN   9780521789103.
  17. ↑ Cruickshank, M. G.; Morrison, D. J.; Lalumiere, A. (2009). "The Interaction Between Competition in Douglas-fir Plantation and Disease Caused by Armillaria ostoyae in British Columbia". Forest Ecology and Management. 257 (2): 443–452. doi:10.1016/j.foreco.2008.09.013.
  18. ↑ Richardson Dodge, Sherri (24 July 2000). "An even more humongous fungus". Pacific Northwest Research Station, US Forest Service. Retrieved 2 November 2015.
  19. ↑ Elizabeth Pennisi (10 October 2018). "'Humongous fungus' is almost as big as the Mall of America". Science, American Association for the Advancement of Science. Retrieved 23 September 2019.
  20. ↑ "CTD-Root Disease: Armillaria Root Disease". Forestry Development. 19 March 2009. Archived from the original on 30 August 2010. Retrieved 7 December 2010.
  21. ↑ "Armillaria Root Rot, Shoestring Root Rot, Honey Mushroom". Forest Health Notes. Washington State University – Department of Natural Resource Science Extension. Archived from the original on 4 March 2016. Retrieved 11 June 2013.
  22. ↑ Miller Jr., Orson K.; Miller, Hope H. (2006). North American Mushrooms: A Field Guide to Edible and Inedible Fungi. Guilford, CN: FalconGuide. p. 153. ISBN   978-0-7627-3109-1.
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