Lachnellula willkommii (European larch canker)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- List of Symptoms/Signs
- Biology and Ecology
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Plant Trade
- Impact Summary
- Environmental Impact
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Lachnellula willkommii (Hartig) Dennis 1962
Preferred Common Name
- European larch canker
Other Scientific Names
- Dasyscyphus willkommii (Hartig) Rehm 1881
- Helotium willkommii (Hartig) Wettst. 1887
- Lachnella willkommii (Hartig) Seaver 1951
- Peziza willkommii Hartig 1874
- Trichoscypha willkommii (Hartig) Boud. 1907
- Trichoscyphella willkommii (Hartig) Nannf. 1932
International Common Names
- English: European canker of larch; stem canker of larch
- Spanish: chancro del alerce
- French: chancre du meleze; maladie chancreuse du meleze
Local Common Names
- Germany: Krebs: Laerche
- LCHNWI (Lachnellula willkommii)
Summary of InvasivenessTop of page
The European larch canker pathogen, L. willkommii, is apparently native to Japan, but established in Europe, where it became well known due to its damage to plantations of exotic and native Larix species, beginning in the nineteenth century. It attacks and spreads among the various species of Larix once it has been introduced. It was detected as an invasive to North America on two occasions; once in the northeastern USA in the 1920s (Hahn and Ayres, 1936) and once in the eastern maritime provinces of Canada in the 1980s (Magasi and Pond, 1982).
Efforts to prevent its introduction across natural barriers include regulation and restriction of trade and transport of susceptible species and bark-bearing products made from them. Control by destruction of infected plants or plant parts is often made difficult by the size of the trees concerned (Tegethoff, 1965). Local spread of the fungus between trees appears to depend on dissemination and survival of airborne ascospores. Climatic conditions of humidity and temperature appear to limit natural spread from regions of establishment (Ostaff, 1985).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Fungi
- Phylum: Ascomycota
- Subphylum: Pezizomycotina
- Class: Leotiomycetes
- Subclass: Leotiomycetidae
- Order: Helotiales
- Family: Hyaloscyphaceae
- Genus: Lachnellula
- Species: Lachnellula willkommii
Notes on Taxonomy and NomenclatureTop of page
The placement of this species in a genus has changed with the changing circumscriptions of genera (Oguchi, 1981). Dennis combined Nannfeldt’s genus of Trichoscyphella with Lachnellula, due to the difficulty of separating the genera on the basis of ascospore shape. Within the family, Lachnellula species are characterized by the form of their paraphyses, the colour of external hairs, the shape of ascospores, and their usual occurrence on conifers (Dennis, 1962). With respect to the species, Baral (1984) found that L. willkommii is difficult to distinguish from Lachnellulaoccidentalis on a morphological basis, and that the clearest difference is physiological, i.e. in the pathogenicity of L. willkommii and the saprobicity of L. occidentalis.
DescriptionTop of page
Ascomata: apothecial, 2-4 mm tall, conspicuous, solitary or gregarious, frequently in clusters from two to many, erumpent, breaking through the bark where canker developed; cup-shaped to discoid, with a short, stout stipe; the sides and disk margin covered with conspicuous white hairs, hairs white, cream, beige, pale-brown, to grey in dried specimens.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 30 Jun 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|-Heilongjiang||Present||Introduced||Xinan Ling Mountains|
|Federal Republic of Yugoslavia||Present||Introduced|
|Netherlands||Present, Few occurrences|
|-Eastern Siberia||Present||As Dasyscyphus|
|-Russia (Europe)||Present, Localized|
|-Russian Far East||Present|
|Serbia and Montenegro||Present, Widespread|
|United Kingdom||Present, Widespread|
|-New Brunswick||Present||Introduced||Invasive||Introduced before 1958|
|-Prince Edward Island||Present, Few occurrences|
|United States||Present, Localized|
|-Maine||Present||Introduced||Invasive||Presence connected to occurences in Canada|
History of Introduction and SpreadTop of page
The species is considered to be native to Asia, particularly Japan (Ito et al., 1963; Kobayashi, 1970). It is established and widespread in Europe, with awareness of its presence and damage in Europe increasing as larch plantations were created in the nineteenth century (Hahn and Ayres, 1936; Dominique, 2003). The fungus was found as an invasive in the USA (Massachusetts) in the 1920s and successfully eradicated by 1965 (Tegethoff, 1965). It appeared again in the USA (eastern Maine) in the 1980s, after it was found in eastern maritime Canada (Miller-Weeks and Stark, 1983), where the focus of introduction appeared to be the port of St. John in New Brunswick (Ostaff, 1985). The ages of cankers indicated that an introduction occurred as early as 1957. Prince Edward Island in Canada was surveyed for the pathogen during the next decade, but the fungus was not observed there until 1992. The infected material found on the island was destroyed (Simpson and Harrison, 1993), but a portion of the island remains in a regulated zone that includes parts of the other two affected provinces (see the Canadian Food Inspection Agency (CFIA) website at http://www.inspection.gc.ca for further details). At about the same time, the fungus was identified as being present in Iceland (Roll-Hansen, 1992).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|Maine||<1971||Self-propelled (pathway cause)||Miller-Weeks and Stark (1983)||Accidental|
|Massachusetts||UK||1904||Horticulture (pathway cause)||No||Tegethoff (1965)||Accidental. Eradicated by 1965|
|New Brunswick||<1958||Ostaff (1985)||Accidental|
|Nova Scotia||<1980||Magasi and Pond (1982)||Accidental|
|Prince Edward Island||<1993||No||Simpson and Harrison (1993)||Accidental|
Risk of IntroductionTop of page
Introduction would result, as in the past, from trade in nursery stock, but also from larch wood and wood products bearing bark. Both Canada and the USA restrict movement of such materials from the provinces of New Brunswick and Nova Scotia (CFIA, 2008; USDA/APHIS, 2009). Nevertheless, the pathogen is able to spread naturally from tree to tree on land, and airborne ascospores may also have been its means of crossing water to reach Prince Edward Island, Canada.
HabitatTop of page
The fungus prefers cool, moist forest conditions. In Japan, the disease occurs at altitudes of 1400-1700 m, on natural stands and in plantations in the central region of Honshu (Ito et al., 1963). In Europe, the damage is greater on trees grown in the lowlands compared to those of the Alps, though this may be due to lowland conditions affecting the health and vigour of Larix genotypes adapted to an alpine climate (Sylvestre-Guinot and Delatour, 1983). Highest rates of infection in the cold climate of New Brunswick, Canada, occurred near the coast, where rainfall was greatest, snowfall was least, and maximum and mean temperatures were greatest (Ostaff, 1985).
Habitat ListTop of page
|Terrestrial||Managed||Managed forests, plantations and orchards||Present, no further details||Harmful (pest or invasive)|
|Terrestrial||Natural / Semi-natural||Natural forests||Present, no further details||Harmful (pest or invasive)|
Hosts/Species AffectedTop of page
Host Plants and Other Plants AffectedTop of page
|Larix (larches)||Pinaceae||Wild host|
|Larix decidua (common larch)||Pinaceae||Main|
|Larix gmelinii (Dahurian larch)||Pinaceae||Main|
|Larix kaempferi (Japanese larch)||Pinaceae||Main|
|Larix laricina (American larch)||Pinaceae||Main|
|Larix marschlinsii (hybrid larch)||Pinaceae||Other|
|Larix occidentalis (western larch)||Pinaceae||Other|
|Larix sibirica (Siberian larch)||Pinaceae||Other|
|Pseudolarix amabilis (chinese golden larch)||Pinaceae||Other|
SymptomsTop of page
The fungus kills the growing bark, resulting in swellings on twigs and branches, and sunken cankers on larger stems. The first circular or elliptical depressions often form around dwarf shoots. Resin is exuded. The bark cracks and is loosened. A ridge of wood develops around enlarging cankers on stems and trunks as the tree grows. Needles above the canker shrivel up and die or turn yellow early. If the stem or trunk is girdled, branches and young trees will die (Sinclair and Lyon, 2005).
List of Symptoms/SignsTop of page
|Leaves / yellowed or dead|
|Stems / canker on woody stem|
|Stems / gummosis or resinosis|
Biology and EcologyTop of page
ClimateTop of page
|Df - Continental climate, wet all year||Preferred||Continental climate, wet all year (Warm average temp. > 10°C, coldest month < 0°C, wet all year)|
|Dw - Continental climate with dry winter||Preferred||Continental climate with dry winter (Warm average temp. > 10°C, coldest month < 0°C, dry winters)|
Means of Movement and DispersalTop of page
Natural Dispersal (Non-Biotic)
The fungus was introduced to Massachusetts, USA, on nursery stock in 1904 (Tegethoff, 1965) and in some way, presumably through the port of St. John, New Brunswick, Canada, before 1958 (Ostaff, 1985).
Pathway CausesTop of page
Pathway VectorsTop of page
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Bark||fruiting bodies; hyphae; spores||Yes||Yes||Pest or symptoms usually invisible|
|Stems (above ground)/Shoots/Trunks/Branches||fruiting bodies; hyphae; spores||Yes||Yes||Pest or symptoms usually invisible|
|Plant parts not known to carry the pest in trade/transport|
Impact SummaryTop of page
Environmental ImpactTop of page
Risk and Impact FactorsTop of page
- Invasive in its native range
- Proved invasive outside its native range
- Host damage
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
DiagnosisTop of page
A number of related and similar species occur on the susceptible trees, though most are saprobic, growing only on dead material (Hahn and Ayers, 1943). Microscopic examination of the ascospores, at least, is necessary for the identification of white-haired Lachnellula species found associated with dead parts of Larix and Pseudolarix species. Descriptions of individual species are available (Buczacki, 1975; Oguchi, 1981; Minter, 2005a-j), but a key to most Lachnellula species (Baral, 1984) is not very accessible.
Detection and InspectionTop of page
Living trees and bark-bearing wood must be inspected for the presence of cankers and/or the ascomata of the pathogen. The CFIA regulation provides guidelines, noting that, “Young cankers appear as swellings on twigs and branches, or as depressions on larger stems and are accompanied by exuding resin”. The fruiting bodies “in or around the canker during most of the year” are also described. Inspectors must also watch for withered, dead and/or discolored needles, checking dead or dying branches and stems carefully (CFIA, 2008).
Similarities to Other Species/ConditionsTop of page
Among the species of Lachnellula occurring on Larix, most are primarily saprobic or only weakly pathogenic. Based on Minter’s descriptions (Minter, 2005a-j), L. willkommiii can be easily distinguished from Lachnellula arida and Lachnellula flavovirens by having white (instead of brown) external hairs and broader ascospores. Among the other white-haired species, it can be distinguished from most species (except Lachnellula occidentalis) by its broad, cylindrical ascospores. Ascospores of Lachnellula subtiliissima are fusiform and those of Lachnellula suecica are globose.
Usually on dead branches. Ascomata olive-green to brown with brown hairs, up to 190 µm long. Ascospores shorter and narrower, 6-9 x 3.5-5.0 µm. Present in North America and Europe (Minter, 2005a).
Usually on dead branches. Ascospores narrow, 2.5-3.5 µm. Paraphyses significantly shorter (60-70). Present in North America, Asia and Europe (Minter, 2005b).
Spores fusiform and narrow, 15-22 x 2-3 µm. In North America (Baral, 1984).
Usually on dead branches. Hairs brown, up to 300 µm long. Ascospores narrow, 3.5-5.5 µm. Present in North America, Asia and Europe (Minter, 2005c).
In North America and Europe. Ascospores shorter and narrower, 12-16 x 5.5-7.5 µm. In USA and Europe (Baral, 1984).
Usually on dead branches. Has narrower ascospores, 5.0-8.5 µm wide. Present in North America, Asia and Europe (Minter, 2005e).
Spores much shorter, (2.0-)2.5-4.0(-4.5) µm. In North America, Asia and Europe (Baral, 1984).
Usually on dead branches. Has short and narrow fusiform ascospores, 6-11 x 2.0-2.5 µm. Present in North America, Asia and Europe (Minter, 2005i).
Ascospores globose, 4-6(-7) µm diameter. Asci shorter, 60-70 µm long. Present in North America, Asia and Europe (Minter, 2005j).
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Gaps in Knowledge/Research NeedsTop of page
Despite its presence in Japan, Russia and northeastern China, the fungus has not been reported in Korea.
ReferencesTop of page
Baral HO, 1984. [English title not available]. (Taxonomische und okologische studien uber die koniferen bewohnenden europaischen arten der gattung Lachnellula Karsten.) Beitrage zur Kenntnis der Pilze Mitteleuropas, 1:143-156.
Blanchette JY, 2001. Microscopic observations of the early stages of the infection process by Lachnellula willkommii (Hartig) Dennis artificially inoculated on larch (Larix laricina (Du Roi) K. Koch) seedlings. Fredericton, Canada: The University of New Brunswick.
BPI (US National Fungus Collections), 2009. Fungal Databases - Specimens. Beltsville, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service, USDA. www.nt.ars-grin.gov/fungaldatabases/specimens/specimens.cfm
Chen MM, 2002. Forest fungi phytogeography: Forest fungi phytogeography of China, North America, and Siberia and international quarantine of tree pathogens. Sacramento, USA: Pacific Mushroom Research and Education Center, 469 pp.
Dominique J, 2003. Amelioration du module de l'elasticite du bois de meleze hybride (Larix ?eurolepis Henry) par selection clonale ([English title not available]). Gembloux, Belgium: Faculte Universitaire des Sciences Agronomiques de Gembloux.
EPPO, 2000. Report of the EPPO Forestry Project: Forest pests on the territories of the former USSR. Paris, France: EPPO, 234 pp. http://www.eppo.org/QUARANTINE/forestry_project/EPPOforestry_project.pdf
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Morozova TI; Tkacz B, 1997. Diseases in the forest. Eastern Siberia and the Russian Far East. In: Hansen EM, Lewis KJ, ed. Compendium of conifer diseases. The American Phytopathological Society, St. Paul, MN, USA: APS Press, 77-79.
Sylvestre-Guinot G, 1981. [English title not available]. (Etude de l'émission des ascospores du Lachnellula willkommii (Hartig) Dennis dans l'Est de la France.) European Journal of Forest Pathology, 11:275-283.
Sylvestre-Guinot G; Delatour C, 1983. [English title not available]. (Possibilites d'appreciation de la sensibilite du genre Larix au Lachnellula wilkommii (Hartig) Dennis par inoculations artificielles.) Annales de Science Forestiere, 40:337-354.
BPI (US National Fungus Collections), 2009. Fungal Databases - Specimens., Beltsville, USA: Systematic Mycology and Microbiology Laboratory, Agricultural Research Service, USDA. http://www.nt.ars-grin.gov/fungaldatabases/specimens/specimens.cfm
CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Chen M M, 2002. Forest fungi phytogeography: Forest fungi phytogeography of China, North America, and Siberia and international quarantine of tree pathogens. Sacramento, USA: Pacific Mushroom Research and Education Center. 469 pp.
Dudka I O, Heluta V P, Tykhonenko Y Y, Anrianova T V, Hayova V P, Prydiuk M P, Dzhagan V V, Isikov V P, 2004. Fungi of the Crimean Peninsula. Kiev, Ukraine: National Academy of Sciences of Ukraine. 452 pp.
EPPO, 2000. Report of the EPPO Forestry Project: Forest pests on the territories of the former USSR. In: Report of the EPPO Forestry Project: Forest pests on the territories of the former USSR, Paris, France: EPPO. 234 pp. http://www.eppo.org/QUARANTINE/forestry_project/EPPOforestry_project.pdf
EPPO, 2014. EPPO Global database (available online). Paris, France: EPPO. https://gd.eppo.int/
Morozova TI, Tkacz B, 1997. Diseases in the forest. Eastern Siberia and the Russian Far East. In: Compendium of conifer diseases, [ed. by Hansen EM, Lewis KJ]. St. Paul, MN, USA: The American Phytopathological Society, APS Press. 77-79.
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