Mycosphaerella populorum (septoria leaf spot)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Means of Movement and Dispersal
- Plant Trade
- Wood Packaging
- Environmental Impact
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Mycosphaerella populorum G.E. Thomps. 1941
Preferred Common Name
- septoria leaf spot
Other Scientific Names
- Septoria musiva Peck 1884
International Common Names
- English: canker: poplar; septoria canker; septoria canker of poplar
Local Common Names
- Germany: Krebs: Pappel
- MYCOPP (Mycosphaerella populorum)
Summary of InvasivenessTop of page
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Fungi
- Phylum: Ascomycota
- Subphylum: Pezizomycotina
- Class: Dothideomycetes
- Subclass: Dothideomycetidae
- Order: Capnodiales
- Family: Mycosphaerellaceae
- Genus: Mycosphaerella
- Species: Mycosphaerella populorum
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
DistributionTop of page
See also CABI/EPPO (1998, No. 220).
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: 17 Feb 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Russia||Absent, Unconfirmed presence record(s)|
|Ukraine||Absent, Unconfirmed presence record(s)|
|United States||Present, Localized|
Risk of IntroductionTop of page
Hosts/Species AffectedTop of page
The incidence and severity of disease have been high in plantings of susceptible hybrids in central and eastern North America. However, susceptibility to either leaf spot or canker disease varies greatly among clones resulting from interspecific hybridization. Among the highly susceptible clones are many with parentage of P. balsamifera subsp. trichocarpa, P. maximowiczii (Japanese poplar) and P. nigra (European black poplar).
The host range and variation among clones in both the incidence and severity of septoria leaf spot and canker diseases is detailed in numerous papers containing anecdotal observations, descriptions of experimental studies and field surveys (e.g., Bier, 1939; Thompson, 1941; Waterman, 1954; Ostry and McNabb, 1985; Hansen et al., 1994). However, conclusions from field surveys have not always been supported by isolation or identification of the pathogen, and some authors have been careful not to attribute canker damage observed in the field solely to M. populorum (Lo et al., 1995). The potential for prediction of long-term canker disease damage from the responses of juvenile poplar clones to inoculation with M. populorum was demonstrated by Weiland et al. (2004).
Host Plants and Other Plants AffectedTop of page
Growth StagesTop of page
SymptomsTop of page
On young, current-year shoots, lesions appear to develop from infection through leaf petioles, at stipules, stipule scars and leaf scars, through lenticels, at wounds, and through uninjured bark. Lesions enlarge to form elongate, often depressed, cankers that are dark brown or black but may include lighter brown or tan areas. Irregular concentric rings may appear in the bark of rapidly expanding cankers on highly susceptible hosts. Stems may be constricted at the canker, or appear swollen due to the production of callus. As cankers enlarge they often become more irregular. The vascular cambium may be killed and underlying wood discoloured to the pith. The stems of highly susceptible clones may be girdled in their first season of growth. Conidioma may develop in cankers within 4 weeks of infection, and pseudothecia have been found in cankers formed in the previous year.
The appearance of cankers on older stems is highly variable, and may be influenced by the invasion of other canker-producing fungi such as species of Cytospora or Phomopsis. The main stems may become infected by the expansion of cankers on lateral branches. Stem cankers may be largely restricted or become perennial to increase in size over time. Some stems persist with multiple disfiguring clones for years, whereas others are rapidly girdled and killed. Decay can develop within cankered stems and weakened stems are often broken, with adventitious shoots produced below damaged areas.
List of Symptoms/SignsTop of page
|Leaves / abnormal colours|
|Leaves / abnormal leaf fall|
|Leaves / fungal growth|
|Leaves / necrotic areas|
|Leaves / yellowed or dead|
|Stems / canker on woody stem|
|Stems / discoloration|
|Stems / discoloration of bark|
|Stems / gummosis or resinosis|
|Stems / lodging; broken stems|
|Stems / necrosis|
|Stems / ooze|
|Whole plant / plant dead; dieback|
Biology and EcologyTop of page
Although inherent resistance or susceptibility of hosts is an important determinant of the incidence and severity of disease, site conditions may also influence canker development. Canker disease ratings often reflected more severe damage to clones growing on harsh sites than on good sites in a clonal field performance trial in the north-central USA (Hansen et al., 1994). In greenhouse experiments, cankers were larger on inoculated, water-stressed poplars than on non-stressed trees (Maxwell et al., 1997).
Means of Movement and DispersalTop of page
Under natural conditions, M. populorum ascospores are windborne and Septoria musiva conidia are disseminated in water (rainsplash or stem flow). Either form of inoculum could be disseminated from colonized leaves moved by wind or water. The potential for spread by animals has not been studied, but spores could be casually acquired and spread by insects, birds, etc.
Movement in Trade/Transport
In trade, M. populorum could be moved on or in cuttings, infected seedling leaves and stems, cankered bark of trees, and colonized bark or wood of logs or green lumber.
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||Yes||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Leaves||Yes||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Seedlings/Micropropagated plants||Yes||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Stems (above ground)/Shoots/Trunks/Branches||Yes||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Wood||Yes||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
Wood PackagingTop of page
|Wood Packaging not known to carry the pest in trade/transport|
|Loose wood packing material|
|Processed or treated wood|
|Solid wood packing material with bark|
|Solid wood packing material without bark|
ImpactTop of page
Environmental ImpactTop of page
DiagnosisTop of page
Detection and InspectionTop of page
Similarities to Other Species/ConditionsTop of page
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.Phytosanitary Measures
The programme on EPPO pest-specific phytosanitary measures (former specific quarantine requirements) is under complete revision and standard PM 2/17(4) is no longer available and will be replaced in due course by a revised version (EPPO, 2002b). However, the European and Mediterranean Plant Protection Organization (OEPP/EPPO, 1990) has recommended that all countries should prohibit the importation of plants for planting, cut branches and isolated bark of Populus from the Americas. If wood is imported from the Americas, the consignment must have been debarked or kiln dried. However, M. populorum has been isolated from wood, so debarking may not be adequate to prevent the introduction and possible survival of M. populorum in wood, and this requires further investigation.
Cultural Control and Sanitary Methods
Burying leaves in the soil by ploughing should reduce primary inoculum but will not eliminate the pathogen from infested locations because M. populorum can survive in cankers on trees.
The use of resistant or tolerant poplar clones is the only practical management strategy for commercial production areas.
The inhibition of leaf spot development by strains of Streptomyces and by the fungus Phaeotheca dimorphospora has been studied (Yang et al., 1994; Gyenis et al., 2003), but efficacy and economic benefits in commercial poplar production have not been demonstrated.
Multiple fungicide applications have reduced the incidence of canker on susceptible poplar clones in nursery stool beds (Ostry, 1987). Both hot-water and chemical treatments have been tested for surface disinfestation of artificially infested cuttings (Waterman and Aldrich, 1952; 1954). Hot-water treatment produced lethal effects on cuttings. Some chemicals reduced the frequency of isolation of fungi from buds and lenticels, but whether M. populorum was eliminated completely was unclear and additional research was recommended.
ReferencesTop of page
Anon., 1960. Index of Plant Diseases in the United States. Crops Research Division, Agricultural Research Service, Agriculture Handbook No. 165. Washington, USA: United States Department of Agriculture.
Anon., 1970. California Fungi (Exsiccati set), Nos. 1-1325. Herbarium, University of California, Berkeley, California, USA.
Bier JE, 1939. Septoria canker of introduced and native hybrid poplars. Canadian Journal of Research, 17:195-204.
Conners IL, 1967. An annotated index of plant diseases in Canada and fungi recorded on plants in Alaska, Canada and Greenland. Research Branch, Canada Department of Agriculture, Publ. 1251.
EPPO, 1990. Specific quarantine requirements. EPPO Technical Documents, No. 1008. Paris, France: European and Mediterranean Plant Protection Organization.
EPPO, 2002. EPPO A1 Quarantine List 2002-09. http://www.eppo.org/QUARANTINE/lists.html#a1.
EPPO, 2002. Pest specific phytosanitary measures. http://www.eppo.org/standards/sqr.html.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Eriksson OE; Baral H-O; Currah RS; Hansen K; Kurtzman CP; Rambold; G; Laess¢e T, eds. , 2003. Outline of Ascomycota - 2003. Myconet, 9:1-89.
Filer TH Jr, 1975. Septoria leafspot and canker on cottonwood. In: Peterson GW, Smith RS, eds. Forest Nursery Diseases in the United States. USDA Forest Service, Agriculture Handbook, 470, 101-102.
Filer TH; McCracken FI; Mohn CA; Randall WK, 1971. Septoria canker on nursery stock of Populus deltoides. Plant Disease Reporter, 55:460-463.
Gyenis L; Anderson NA; Ostry ME, 2003. Biological control of Septoria leafspot disease of hybrid poplar in the field. Plant Disease, 87:809-813.
Hanlin RT, 1963. A revision of the Ascomycetes of Georgia. Georgia Agricultural Experiment Station, Mimeo Series n.s., 175:1-65.
Hansen EA; Ostry ME; Johnson WD; Tolsted DN; Netzer DA; Berguson WE; Hall RB, 1994. Field performance of Populus in short-rotation intensive culture plantations in the north-central US. USDA Forest Service Research Paper NC-320.
Lo MH; Abrahamson LP; White EH; Manion PD, 1995. Early measures of basal area and canker disease predict growth potential of some hybrid poplar clones. Canadian Journal of Forest Research, 25(7):1113-1118
Mio LLMde; Amorim L, 2000. Diseases of poplars. (Doenças do álamo.) Floresta [Seminário de atualidades em proteção florestal: incênios, pragas e doencas, 06 a 08 de novembro de 2000, Curitiba, PR.], 30(1/2):139-153.
Ostry ME; Wilson LF; McNabb HS Jr, 1989. Impact and control of Septoria musiva on hybrid poplars. General Technical Report - North Central Forest Experiment Station, USDA Forest Service, No. NC-133:5 pp.
Peck CH, 1884. Report of the state botanist. New York State Museum Report 35, 125-164.
Preston DA, 1945. Host index of Oklahoma plant diseases. Oklahoma Agricultural College, Agricultural Experiment Station Technical Bulletin (suppl.), T-21:1-39.
Sarasola AA, 1944. Dos septoriosis de las alamedas Argentinas. Rev. Argentina de Agron., 11:20-43.
Sprague R, 1955. A checklist of fungi of glacier bay, Alaska. Res. Stud. State Coll. Wash., 23:202-224.
Waterman AM, 1954. Septoria canker of poplars in the United States. USDA Circular 947.
Waterman AM; Aldrich KF, 1952. Surface sterilization of poplar cuttings. Plant Disease Reporter, 36:203-207.
Waterman AM; Aldrich KF, 1954. Additional information on the surface sterilization of poplar cuttings. Plant Disease Reporter, 38:96-100.
Weiland JE; Stanosz JC; Stanosz GR, 2004. Prediction of long-term canker disease damage from responses of juvenile poplar clones to inoculation with Septoria musiva. Plant Disease (in press).
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Filer TH Jr, 1975. Septoria leafspot and canker on cottonwood. In: Forest Nursery Diseases in the United States, 470 [ed. by Peterson GW, Smith RS]. USDA Forest Service, Agriculture Handbook. 101-102.
Hanlin RT, 1963. A revision of the Ascomycetes of Georgia. In: Georgia Agricultural Experiment Station, Mimeo Series n.s, 175 1-65.
Romo Lozano Y, Moreno Rico O, Romero Cova S, 1992. Incidence and severity of quaking aspen (Populus tremuloides) aerial diseases in Aguascalientes, Ags. (Incidencia y severidad de las enfermedades fungosas aéreas del Álamo temblón (Populus tremuloides) en Aguascalientes, Ags.). Revista Mexicana de Fitopatología. 10 (1), 38-43.
Sprague R, 1955. A checklist of fungi of glacier bay. In: Alaska. Res. Stud. State Coll. Wash. 23 202-224.
Distribution MapsTop of page
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