Heterobasidion irregulare

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Heterobasidion irregulare
Heterobasidion irregulare at Portage WI.jpg
Scientific classification
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H. irregulare
Binomial name
Heterobasidion irregulare
Garbel. & Otrosina (2010)
Synonyms

Polyporus annosus
Fomes annosus
Heterobasidion annosumHeterobasidon irregulare

Contents

Heterobasidion irregulare is a tree root rotting pathogenic fungus that belongs to the genus Heterobasidion , which includes important pathogens of conifers and other woody plants. It has a wide host and geographic range throughout North America and causes considerable economic damage in pine plantations in the United States. This fungus is also a serious worry in eastern Canada. Heterobasidion irregulare has been introduced to Italy (Lazio)(modifica) where it has been responsible for extensive tree mortality of stone pine. [1] Due to the ecology, disease type, host range/preference, interfertility group, and genetic information, H. irregulare (formerly known as Heterobasidion annosum P ISG) was designated a new species and distinguished from Heterobasidion occidentale (formerly known as Heterobasidion annosum S ISG). [2]

Hosts, Symptoms and Signs

Classic root disease center symptoms for H. irregulare Root disease center, H irregulare.jpg
Classic root disease center symptoms for H. irregulare

Many woody plant species have been reported as hosts for H. irregulare. Hosts consist of pines and some other conifers and hardwoods, including ponderosa pine (Pinus ponderosa), [3] shortleaf pine (Pinus echinata), red pine (Pinus resinosa), [4] incense-cedar (Calocedrus decurrens), western juniper (Juniperus occidentalis), and Manzanita (Arctostaphylos spp.). [3]

Heterobasidion irregulare causes both above and below-ground symptoms. Above-ground symptoms of infected trees consist of reduced height growth, patches of dead and declining trees, wind-thrown trees, reduced shoot and diameter growth, and resin-soaking at the root collar. Additionally, the crown may become thin and foliage (leaves or needles) becomes chlorotic. The characteristic symptom of most tree root disease, including this type, is a disease center.g This occurs when the fungus has infected one tree and then spreads through the roots to other trees and kills them too. This creates a pattern of old dead trees in the center of the pocket and progressively newer dead, chlorotic, then healthy trees, usually in a circular area. Below-ground symptoms of H. irregulare include excessive pitch production, stringy, white root decay, and root lesions. Signs include the formation of white mycelia between bark scales followed by conks (fruit bodies) that usually form in the duff layer at the base of the tree or stump. [5] [6] [7] The fruit bodies can also form as "foam" on the ground rising from roots under the surface.[ citation needed ]

Disease cycle

The disease cycle of Heterobasidion irregulare begins with natural wounds on trees or cut stumps. Basidiospores are wind-blown and land on tree wounds. Most spores land within 100 metres of the fruiting bodies. [8] The spores then germinate and the mycelia, or vegetative structure of the fungus, grows into the wood. The mycelia colonizes the wood by decomposing the lignin and cellulose, producing a stringy white rot. It spreads from tree to tree by root grafts, killing trees in an ever-widening circle. [9] The sexual reproductive structures of the fungus, annual or perennial basidiocarps, appear on decomposing stumps and at the base of dead trees and release spores in summer and fall to mid-winter. [10] The highest sporulation occurs from late summer to when the conks freeze. When the conk temperatures are above freezing the spores of the fungus are released and carried by wind currents to land in open wounds or stumps of cut trees. [9] The fungus can survive freezing temperatures both as mycelia and as basidiocarps, and overwinters in the roots and stem tissue of trees. The mycelia produce infectious conidia, but it is unknown how these fit into the disease cycle. When the fungus has obtained enough nutrients it grows a basidiocarp on the outside of a trunk or stump of a tree in the eastern US or inside a hollow stump in the western US. [2]

Environment

Various abiotic factors attribute to the ability of Heterobasidion irregulare to cause disease on trees. Factors such as gaseous regime (oxygen levels), pH of the soil, and moisture content, may affect fungal growth. [11] Disease is most severe on high fertility or lime, alkaline (pH>6), or former agricultural soils. H. irregulare grows best on well drained sandy soils, which are now farm fields that have been converted into plantations in the southern US. [12] Plantations particularly favor this fungus because it enters the plant through a wound or cut surface and then spreads by the roots. [4] Research on temperature requirements for germination and spore production is currently being conducted. It is known however, that H. irregulare is able to germinate at temperatures as low as 8 °C (46 °F). [13]

Management

The best strategy to manage this disease is to avoid infection of stumps. To do this, do not cut trees at major sporulation times, which are summer to late fall, and treat fresh stumps with protectants such as borax, which is registered as cellu-treat or sporax, either as a powder or in aqueous form. These treatments are most effective if done immediately after stump is created (the tree is cut). Other control measures include: use wide spacing when planting to reduce the need for thinning and reduce the potential root grafts, thin only when spores are less abundant, (January through March), and plant tree species that are less susceptible. [9] Another strategy is to avoid logging injuries as the spores enter through such injuries and infect and kill the tree and begin a disease center. Once the fungus is in the stand there is nothing that can be done about it except extremely expensive stump removal and prevention of new infections.[ citation needed ]

There are bio-controls used in Europe against the Heterobasidion species found there. However, they are not approved for use in the United States and it is uncertain whether they work on Heterobasidion irregulare because of the recent naming of this species, and not much research has been done outside of the US on its reaction to biocontrols.[ citation needed ]

Importance

This disease is economically important because of its effect on timber species, especially in plantations in the Midwest and Southeast in the United States. It destroys commercially viable trees and causes losses both from reduction of marketable wood and increased cost of treatment to growers. It reduces both volume and height growth as well as eventually killing the trees and causing them to be more susceptible to windthrow and other diseases and insects. In the Southeastern US it was found that as many as 30% of trees can be killed in severely infected stands. [4]

Heterobasidion irregulare is also an ecologically important disturbance agent in natural settings. It creates gaps in forest canopies, allowing light and water to get through, which in turn allows a diversity of plants to establish. It also stresses trees, making them more susceptible to different fungi and insects, particularly bark beetles. [14] These stressed trees can then act as a source of infection by other organisms of nearby healthy trees.[ citation needed ]

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.

<span class="mw-page-title-main">Polypore</span> Group of fungi

Polypores are a group of fungi that form large fruiting bodies with pores or tubes on the underside. They are a morphological group of basidiomycetes-like gilled mushrooms and hydnoid fungi, and not all polypores are closely related to each other. Polypores are also called bracket fungi or shelf fungi, and they characteristically produce woody, shelf- or bracket-shaped or occasionally circular fruiting bodies that are called conks.

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

Armillaria mellea, commonly known as honey fungus, is a 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.

<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>Ganoderma zonatum</i> Species of fungus

Ganoderma zonatum is a plant pathogen that infects the palm species causing butt rot. It is a fungus that infects the bottom 4–5 feet (122–152 cm) of the plant also rotting the roots. It has been known to be in both natural and planted environments and in the majority of cases only in palms.

<i>Rigidoporus microporus</i> Species of fungus

Rigidoporus microporus is a plant pathogen, known to cause white root rot disease on various tropical crops, such as cacao, cassava, tea, with economical importance on the para rubber tree.

<i>Stereum sanguinolentum</i> Species of fungus

Stereum sanguinolentum is a species of fungus in the Stereaceae family. A plant pathogen, it causes red heart rot, a red discoloration on conifers, particularly spruces or Douglas-firs. Fruit bodies are produced on dead wood, or sometimes on dead branches of living trees. They are a thin leathery crust of the wood surface. Fresh fruit bodies will bleed a red-colored juice if injured, reflected in the common names bleeding Stereum or the bleeding conifer parchment. It can be the host of the parasitic jelly fungus Tremella encephala.

<i>Phellinus pini</i> Species of fungus

Phellinus pini is a fungal plant pathogen that causes tree disease commonly known as "red ring rot" or "white speck". This disease, extremely common in the conifers of North America, decays tree trunks, rendering them useless for lumber. It is a rot of the heartwood. Signs of the fungus include shelf-shaped conks protruding from the trunks of trees. Spores produced on these conks are blown by the wind and go on to infect other trees. Formal management of this disease is limited, and the disease is controlled primarily by cultural practices. Red ring rot is an important forest disturbance agent and plays a key role in habitat formation for several forest animals.

<i>Phaeolus schweinitzii</i> Species of fungus

Phaeolus schweinitzii, commonly known as velvet-top fungus, dyer's polypore, dyer's mazegill, or pine dye polypore, is a fungal plant pathogen that causes butt rot on conifers such as Douglas-fir, spruce, fir, hemlock, pine, and larch. P. schweinitzii is a polypore, although unlike bracket fungi the fruiting body may appear terrestrial when growing from the roots or base of the host tree.

<i>Laminated root rot</i>

Laminated root rot also known as yellow ring rot is caused by the fungal pathogen Phellinus weirii. Laminated root rot is one of the most damaging root disease amongst conifers in northwestern America and true firs, Douglas fir, Mountain hemlock, and Western hemlock are highly susceptible to infection with P. weirii. A few species of plants such as Western white pine and Lodgepole pine are tolerant to the pathogen while Ponderosa pine is resistant to it. Only hardwoods are known to be immune to the pathogen.

<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.

Forest pathology is the research of both biotic and abiotic maladies affecting the health of a forest ecosystem, primarily fungal pathogens and their insect vectors. It is a subfield of forestry and plant pathology.

<i>Fomes fomentarius</i> Species of fungus

Fomes fomentarius is a species of fungal plant pathogen found in Europe, Asia, Africa and North America. The species produces very large polypore fruit bodies which are shaped like a horse's hoof and vary in colour from a silvery grey to almost black, though they are normally brown. It grows on the side of various species of tree, which it infects through broken bark, causing rot. The species typically continues to live on trees long after they have died, changing from a parasite to a decomposer.

<i>Armillaria</i> root rot

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.

<i>Heterobasidion</i> Genus of fungi

Heterobasidion is a genus of basidiomycetes in the family of Bondarzewiaceae. Species in this genus include tree decay fungi that may be pathogenic and cause deterioration of tree health including mortality. Fungi in the genus produce shelf-like polyporous fruiting bodies that release spores from pores. Mating studies in the late twentieth century and genetic studies in the early twenty-first century have led to description of several new species and replacement of some of the original names. As a result, two former Heterobasidion species, H. annosum and H. insulare, are now recognized to each comprise multiple distinct species.

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

Armillaria ostoyae 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. 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"). 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.

<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.

References

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  2. 1 2 Otrosina, W. J., Garbelotto M.2010. Heterobasidion occidentale sp. nov. and Heterobasidion irregulare nom. nov.: A disposition of North American Heterobasidion biological species. Fungal Biology 114 (2010) 16–25
  3. 1 2 Drummond, D. B; Bretz, T. W. 1967. Seasonal fluctuations of airborne inoculum of Fomes annosus in Missouri. Phytopathology 57: 340.
  4. 1 2 3 Robbins, K.1984. Annosus Root Rot in Eastern Conifers. Forest insect and disease leaflet 76 U.S. Department of Agriculture Forest Service.
  5. Cram M. M. 2009. Annosum Root Rot. Heterobasidion annosum. http://www.bugwood.org/factsheets/98-031.html
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  8. Gontheir, P; Lione, G; Giodana, L; Garbelotto, M (2012). "The American forest pathogen Heterobasidion irregulare colonizes unexpected habitats after its introduction in Italy". Ecological Applications. 22 (8): 2135–2143. doi:10.1890/12-0420.1. PMID   23387115.
  9. 1 2 3 Filip, G. M. and Morrison, D. J., 1998. "North America" edited by Woodward, S.; Stenlid, J.; Karjalainen, R.; and Huttermann, A.; Heterobasidion annosum Biology, Ecology, Impact and Control. Cab International UK, University Press, Cambridge.
  10. Korhonen, K. and Stenlid, J. 1998. "Biology of Heterobasidion annosum" edited by Woodward, S.; Stenlid, J.; Karjalainen, R.; and Huttermann, A.; Heterobasidion annosum Biology, Ecology, Impact and Control. Cab International UK, University Press, Cambridge
  11. Maijala P.2000. Heterobasidion annosum and wood decay: Enzymology of cellulose, hemicellulose, and lignin degradation. http://ethesis.helsinki.fi/julkaisut/mat/bioti/vk/maijala
  12. Froelich, R. C.; Dell, T. R.; Walkinshaw, C. H.1966. Soil Factors Associated with Fomes annosus in the Gulf States. Society of American Foresters. 12:3, 356-361.
  13. Cowling E. B.; Kelman A. 1964. Influence of Temperature Growth of Fomes annosus Isolates.Phytopathology 54: 249-372
  14. Otrosina, William J. and Cobb, Fields W. Jr. 1989. Biology, Ecology, and Epidemiology of Heterobasidion annosum. Proceedings of the Symposium on Research and Management of Annosus Root Disease (Heterobasidion annosum) in Western North America. USDA Forest Service Gen. Tech. Rep. PSW-116