Elsinoë australis (citrus scab)
- 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
- Plant Trade
- 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
- Elsinoë australis Bitanc. & Jenkins
Preferred Common Name
- citrus scab
Other Scientific Names
- Sphaceloma australis Bitanc. & Jenkins
- Sphaceloma fawcettii var. viscosa Jenkins
International Common Names
- English: sweet orange scab
- Spanish: antracnosis del naranjo; costra de los agrios; roña de la naranja dulce; sarna de la naranja dulce; sarna o roña del naranjo dulce
- French: anthracnose de l'oranger; gale des agrumes
- ELSIAU (Elsinoe australis)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Fungi
- Phylum: Ascomycota
- Subphylum: Pezizomycotina
- Class: Dothideomycetes
- Subclass: Dothideomycetidae
- Order: Myriangiales
- Family: Elsinoaceae
- Genus: Elsinoë
- Species: Elsinoë australis
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
Ascomata pulvinate, globose, dark, pseudoparenchymatous, multi-locular, up to 80-120 µm thick. Asci up to 20 per locule, subglobose or ovoid, bitunicate, inner wall thickened at the top, 12-16 µm diameter, eight-spored. Ascospores hyaline, ellipsoidal or oblong-ellipsoidal, with two to four cells, usually constricted at the central septum, 10-12 x 5-6 µm diameter (12-20 x 4-8 µm for E. australis). Only known from Brazil.
Acervuli intra-epidermal or sub-epidermal, scattered or confluent, pseudoparenchymatous. Conidiogenous cells originated from the upper cells of the pseudoparenchyma or from the hyaline or pale-brown phialidic conidiophores, which have two to four septa. Conidia hyaline, unicellular, ellipsoid, biguttulate, 4-8 x 2-3 µm. Mycelium hyaline, scanty, septate, short-branched. Colonies in culture very slow-growing, rose to purple, well raised above the agar surface and covered by tufts of short, erect hyphae. The anamorphs of E. fawcettii and E. australis are practically identical, except that E. fawcettii produces spindle-shaped conidia (10-15 x 2.5 -3.0 µm) on host tissue whereas E. australis does not.
For more information, see Bitancourt and Jenkins (1936), Sivanesan and Critchett (1974a,b,c), Holliday (1980) and Sivanesan (1984).
DistributionTop of page
See also CABI/EPPO (1998, No. 198).
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: 18 May 2022
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Ethiopia||Absent, Invalid presence record(s)|
|Afghanistan||Absent, Unconfirmed presence record(s)|
|Bangladesh||Absent, Invalid presence record(s)|
|India||Absent, Invalid presence record(s)|
|-Tamil Nadu||Absent, Invalid presence record(s)|
|Italy||Absent, Formerly present||1957|
|-Sicily||Absent, Formerly present|
|Netherlands||Absent, Confirmed absent by survey|
|Dominican Republic||Absent, Invalid presence record(s)|
|Guatemala||Absent, Invalid presence record(s)|
|United States||Present, Localized|
|-Alabama||Present, Few occurrences||Baldwin and Mobile counties. Under official control.|
|-Arizona||Present, Few occurrences|
|-Florida||Present, Few occurrences|
|-Louisiana||Present, Few occurrences|
|-Mississippi||Present, Few occurrences|
|-Texas||Present||[Harris and Orange counties.]|
|-New South Wales||Present, Localized||EPPO Reporting Service No. 2012/061: a new pathotype of E. australis was detected on jojoba (Simmondsia chinensis) in 2005. It has not been found on sweet oranges in Australia.|
|-Queensland||Present, Localized||EPPO Reporting Service No. 2012/061: a new pathotype of E. australis was detected on jojoba (Simmondsia chinensis) in 2005. It has not been found on sweet oranges in Australia.|
|Cook Islands||Absent, Unconfirmed presence record(s)|
|Fiji||Absent, Invalid presence record(s)|
|New Caledonia||Absent, Invalid presence record(s)|
|Niue||Absent, Unconfirmed presence record(s)|
|Samoa||Absent, Unconfirmed presence record(s)|
|-Rio de Janeiro||Present|
|-Rio Grande do Sul||Present|
|Ecuador||Absent, Invalid presence record(s)|
Risk of IntroductionTop of page
Hosts/Species AffectedTop of page
Host Plants and Other Plants AffectedTop of page
NAPPO (2011); NAPPO (2013)
|Citrus aurantiifolia (lime)||Rutaceae||Other|
|Citrus limon (lemon)||Rutaceae||Other|
|Citrus natsudaidai (natsudaidai)||Rutaceae||Unknown|
|Citrus reticulata (mandarin)||Rutaceae||Main|
|Citrus sinensis (sweet orange)||Rutaceae||Main|
|Citrus unshiu (satsuma)||Rutaceae||Other|
|Fortunella margarita (oval kumquat)||Rutaceae||Other|
|Simmondsia chinensis (jojoba)||Simmondsiaceae||Other|
Growth StagesTop of page
SymptomsTop of page
List of Symptoms/SignsTop of page
|Fruit / abnormal shape|
|Fruit / lesions: scab or pitting|
|Fruit / premature drop|
Biology and EcologyTop of page
Germination of conidia and infection do not require rainfall, both processes being possible in the presence of free water from dew or fog. A wet period of 2.5-3.5 h is needed for conidial infection. The temperature range required for germination of conidia is 13-32°C, but infection does not take place below 14°C or above 25°C (Whiteside, 1975). The incubation period is at least 5 days. The optimal temperature for disease development is 20-21°C. Fruits are infected when young, i.e. when not more than 20 mm across.
The pathogen is able to survive in scab pustules on fruits remaining on the tree, providing the inoculum for the next season. Even in resistant cultivars, the fungus can survive on diseased shoots from susceptible rootstocks (Whiteside, 1988). For more information, see Yamada (1961) and Whiteside (1975, 1988).
Dissemination of the pathogen is mostly by rain (or irrigation water), although insects and, to a certain extent, wind-carried water droplets containing spores may contribute to the spread of the pathogen. In international trade the pathogen can be carried on infected nursery stock, ornamental citrus plants, and fruits.
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|
|Flowers/Inflorescences/Cones/Calyx||fungi/hyphae; fungi/spores||Yes||Yes||Pest or symptoms usually visible to the naked eye|
|Fruits (inc. pods)||fungi/hyphae; fungi/spores||Yes||Yes|
|Leaves||fungi/hyphae; fungi/spores||Yes||Yes||Pest or symptoms usually visible to the naked eye|
|Stems (above ground)/Shoots/Trunks/Branches||fungi/hyphae; fungi/spores||Yes||Yes||Pest or symptoms usually visible to the naked eye|
|Plant parts not known to carry the pest in trade/transport|
|Growing medium accompanying plants|
ImpactTop of page
In the field, E. fawcettii affects lemons, mandarins, tangelos and grapefruits, whereas most cultivars of oranges and limes are less or not affected. The disease may be serious in the nursery on susceptible rootstocks such as sour oranges, rough lemons, Poncirus trifoliata and Citrus limonia. It may stunt seedlings or make them bushy and difficult to bud. Scabs are present, particularly on the young growth. Infested nursery stock is the primary means by which scab is introduced into new plantings. Severely infected fruits are scarred and distorted and consequently unmarketable. E. australis differs in only causing fruit scab, mainly on oranges and mandarins.
Citrus scab is widespread in areas where suitable conditions of temperature and rainfall or high humidity prevail (wet subtropics and cooler tropics). Elsewhere, it occurs when new flush and fruit set coincide with spells of relatively warm, humid weather. It is also favoured by local conditions such as damp, low-lying areas and dense, shaded citrus groves. Citrus scab is important only in areas where susceptible species or cultivars of citrus fruit are grown for the fresh market and where young plants or new growth develop under favourable conditions of temperature, moisture and shade. Losses largely depend on seasonal and local variations in weather. The disease is not a problem in areas with a limited annual rainfall (less than 1300 mm), long-lasting hot seasons (mean monthly temperature above 24°C) or a dry summer. In the Mediterranean region and, more generally, in citrus-growing areas with a dry climate (e.g. California and Arizona in the USA, where the disease has never become established) scab, even if present, is rare or unimportant.
Detection and InspectionTop of page
Similarities to Other Species/ConditionsTop of page
Citrus scab may be confused with other diseases, e.g. bacterial canker (Xanthomonas campestris pv. citri) and melanose (Diaporthe citri), or with injuries caused by various agents. For illustrations and further information, see Fawcett (1936), Brun (1971), Knorr (1973), Klotz (1978), Whiteside et al. (1988).
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.Citrus scab can be controlled using resistant cultivars (Ieki, 1982; Yoshida and Shichijo, 1984; Reddy et al., 1986) and by fungicide applications both in the nursery and in the orchard. Protectant fungicides may be applied (copper, ferbam, thiram, difenoconazole and chlorothalonil have been used), or systemic fungicides (benomyl, carbendazim) before flushing and after petal fall (see González, 1980; Rao, 1983; Reddy et al., 1983). Benomyl-tolerant strains of the pathogen have been found (Whiteside, 1980).
Crop sanitation, establishing citrus nurseries in dry areas or in greenhouses, and adoption of proper treatments, may help in production of rootstocks and budwood free from the pathogen. The usual procedures for importation of certified citrus planting material should be followed. For more information, see also Knorr (1977) and Roistacher et al. (1977).
ReferencesTop of page
Ash, G. J., Stodart, B., Hyun, J. W., 2012. Black scab of jojoba (Simmondsia chinensis) in Australia caused by a putative new pathotype of Elsinoë australis. Plant Disease, 96(5), 629-634. doi: 10.1094/PDIS-06-11-0465
Brun J, 1971. Les scab des agrumes. Fruits d'Outre Mer, 26:759-767.
Ciccarone A, 1957. Elsinoë australis Bitancourt et Jenkins, causing a citrus scab in Sicily. Rivista di Agrumicoltura, 2:1-36.
Diaz LE; Gimenez G; Zefferino E; Cerdeiras JT, 1992. Relevamiento de especies y biotipos de sarnas de los citrus en Uruguay. (Abstr.) Fitopatol. Bras., 17:165.
EPPO, 2012. EPPO Reporting Service. EPPO Reporting Service. Paris, France: EPPO. http://archives.eppo.org/EPPOReporting/Reporting_Archives.htm
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Hyun, J. W., Paudyal, D. P., 2015. Improved Method to Increase Conidia Production from Isolates of Different Pathotypes of Citrus Scab Pathogen Elsinoe spp. 21(3), 231-234. doi: 10.5423/RPD.2015.21.3.231
Hyun, J. W., Peres, N. A., Yi, S. Y., Timmer, L. W., Kim, K. S., Kwon, H. M., Lim, H. C., 2007. Development of PCR assays for the identification of species and pathotypes of Elsinoë causing scab on citrus. Plant Disease, 91(7), 865-870. doi: 10.1094/PDIS-91-7-0865
Hyun, J. W., Yi, S. H., MacKenzie, S. J., Timmer, L. W., Kim, K. S., Kang, S. K., Kwon, H. M., Lim, H. C., 2009. Pathotypes and genetic relationship of worldwide collections of Elsinoë spp. causing scab diseases of citrus. Phytopathology, 99(6), 721-728. doi: 10.1094/PHYTO-99-6-0721
IPPC, 2010. Detection of sweet orange scab (Elsinoë australis) in Texas and Louisiana, United States. IPPC Official Pest Report, No. USA-11/1. Rome, Italy: FAO. https://www.ippc.int/
Jenkins AE, 1936. Australian citrus scab caused by Saphaceloma fawcettii scabiosa. Phytopathology, 26:195-196.
Klotz LJ, 1978. Fungal, bacterial, and nonparasitic diseases and injuries originating in the seedbed, nursery, and orchard. In: Reuther W, Calavan EC, Carman GE, eds. The Citrus Industry. Vol. IV. Berkeley, USA: University of California.
Knorr LC, 1977. Citrus. In: Hewitt WB, Chiarappa L, eds. Plant health and quarantine in international transfer of genetic resources. Cleveland, USA: CRC Press, 111-117.
Kunta M; Rascoe J; Sa PBde; Timmer LW; Palm ME; Graça JVda; Mangan RL; Malik NSA; Salas B; Satpute A; Sétamou M; Skaria M, 2013. Sweet orange scab with a new scab disease "syndrome" of citrus in the USA associated with Elsinoë australis. Tropical Plant Pathology, 38(3):203-212. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1982-56762013000300004&lng=en&nrm=iso&tlng=en
NAPPO, 2010. Phytosanitary Alert System: Detection of Sweet Orange Scab (Elsinoë australis) in Mississippi. NAPPO. http://www.pestalert.org/oprDetail.cfm?oprID=470
NAPPO, 2011. Detection of Sweet Orange Scab (Elsinoë australis) in Florida and Arizona. https://www.pestalerts.org/official-pest-report/detection-sweet-orange-scab-elsino-australis-florida-and-arizona
NAPPO, 2011. Phytosanitary Alert System: Detection of Sweet Orange Scab (Elsinoë australis) in Florida and Arizona. NAPPO. http://www.pestalert.org/oprDetail.cfm?oprID=475
NAPPO, 2013. Elsinoë australis (Sweet Orange Scab) - Update in California. USA: North American Plant Protection Organization.https://www.pestalerts.org/official-pest-report/elsino-australis-sweet-orange-scab-update-california
NAPPO, 2013. Phytosanitary Alert System: Sweet Orange Scab (Elsinoë australis) detected in California. NAPPO. http://www.pestalert.org/oprDetail.cfm?oprID=571
NAPPO, 2016. Phytosanitary Alert System: Elsinoë australis (Sweet Orange Scab) - APHIS Establishes Quarantined Areas in California for Sweet Orange Scab and Revises the Conditions for Movement of Regulated Fruit and Nursery Stock under the SOS Quarantine. NAPPO. http://www.pestalert.org/oprDetail.cfm?oprID=683
Pelaez Abellan AI; Fernandez Martinez AI; Garcia C, 1986. Antigenic detection of the fungus Sphaceloma fawcettii. Ciencias de la Agricultura, 26:3-8.
Rao NNR, 1983. Efficacy of two copper-based fungicides in the control of citrus scab. Pesticides, 17: 31-33.
Roistacher CN; Calavan EC; Navarro L, 1977. Concepts and procedures for importation of citrus budwood. Proceedings of the International Society of Citriculture, 1:133-136.
Tan MK; Timmer LW; Broadbent P; Priest M; Cain P, 1996. Differentiation by molecular analysis of Elsinoe spp. causing scab diseases of citrus and its epidemiological implications. Phytopathology, 86(10):1039-1044; 19 ref.
Yamada S, 1961. Epidemiological studies on the scab disease of Satsuma orange caused by Elsinoë fawcettii Bitancourt et Jenkins and its control. Tokai-Kinki National Agricultural Experiment Station, Horticultural Station, Special Bulletin No. 2.
Yoshida T; Shichijo T, 1984. Testing for resistance of citrus cultivars to Elsinoe fawcettii and segregation of resistance on hybrid seedlings. Bulletin, Fruit Tree Research Station, Japan, B (Okitsu), No. 11:9-16
Ash G J, Stodart B, Hyun J W, 2012. Black scab of jojoba (Simmondsia chinensis) in Australia caused by a putative new pathotype of Elsinoë australis. Plant Disease. 96 (5), 629-634. DOI:10.1094/PDIS-06-11-0465
CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Costanzo S, Yang P, Zeller K A, Nakhla M K, 2013. Novel PCR-RFLP assay for genetic diversity studies of Elsinoë australis isolates causing scab on citrus. [APS MSA Joint Meeting], USA: The American Phytopathological Society. 372. http://www.apsnet.org/meetings/Documents/2013_Meeting_Abstracts/aps2013abP372.htm
Fan X L, Barreto R W, Groenewald J Z, Bezerra J D P, Pereira O L, Cheewangkoon R, Mostert L, Tian C M, Crous P W, 2017. Phylogeny and taxonomy of the scab and spot anthracnose fungus Elsinoë (Myriangiales, Dothideomycetes). Studies in Mycology. 1-41. DOI:10.1016/j.simyco.2017.02.001
Herb IMI, 1955. Specimen record from the collection in the Herb IMI Database., Kew, UK: Royal Botanic Gardens. http://www.herbimi.info/herbimi/home.htm
Herb IMI, 2021. Specimen record from the collection in the Herb IMI Database., Kew, UK: Royal Botanic Gardens. DOI:http://www.herbimi.info/
Hyun J W, Peres N A, Yi S Y, Timmer L W, Kim K S, Kwon H M, Lim H C, 2007. Development of PCR assays for the identification of species and pathotypes of Elsinoë causing scab on citrus. Plant Disease. 91 (7), 865-870. DOI:10.1094/PDIS-91-7-0865
Hyun J W, Yi S H, MacKenzie S J, Timmer L W, Kim K S, Kang S K, Kwon H M, Lim H C, 2009. Pathotypes and genetic relationship of worldwide collections of Elsinoë spp. causing scab diseases of citrus. Phytopathology. 99 (6), 721-728. DOI:10.1094/PHYTO-99-6-0721
IPPC, 2014. Detection of Elsinoe australis in Japan. Report no. JPN-02/1., https://www.ippc.int/en/countries/japan/pestreports/2014/05/detection-of-elsinoe-australis-in-japan/
Kunta M, Rascoe J, Sa P B de, Timmer L W, Palm M E, Graça J V da, Mangan R L, Malik N S A, Salas B, Satpute A, Sétamou M, Skaria M, 2013. Sweet orange scab with a new scab disease "syndrome" of citrus in the USA associated with Elsinoë australis. Tropical Plant Pathology. 38 (3), 203-212. DOI:10.1590/S1982-56762013005000003
Miles A K, Tan YuPei, Shivas R G, Drenth A, 2015. Novel pathotypes of Elsinoë australis associated with Citrus australasica and Simmondsia chinensis in Australia. Tropical Plant Pathology. 40 (1), 26-34. DOI:10.1007/s40858-015-0005-0
NAPPO, 2010. Detection of Sweet Orange Scab (Elsinoë australis) in Texas and Louisiana., North American Plant Protection Organization Phytosanitary Alert System. https://pestalerts.org/official-pest-report/detection-sweet-orange-scab-elsino-australis-texas-and-louisiana
NAPPO, 2010a. Detection of Sweet Orange Scab (Elsinoë australis) in Mississippi., North American Plant Protection Organization Phytosanitary Alert System. https://pestalerts.org/official-pest-report/detection-sweet-orange-scab-elsino-australis-mississippi
NAPPO, 2011. Detection of Sweet Orange Scab (Elsinoë australis) in Florida and Arizona., North American Plant Protection Organization Phytosanitary Alert System. https://www.pestalerts.org/official-pest-report/detection-sweet-orange-scab-elsino-australis-florida-and-arizona
NAPPO, 2011a. Update for Sweet Orange Scab (Elsinoë australis) in Florida and Arizona., North American Plant Protection Organization Phytosanitary Alert System. https://pestalerts.org/official-pest-report/update-sweet-orange-scab-elsino-australis-florida-and-arizona
NAPPO, 2013. Sweet Orange Scab (Elsinoë australis) detected in California., North American Plant Protection Organization Phytosanitary Alert System. https://pestalerts.org/official-pest-report/sweet-orange-scab-elsino-australis-detected-california
NAPPO, 2016. Phytosanitary Alert System: Elsinoë australis (Sweet Orange Scab) - APHIS Establishes Quarantined Areas in California for Sweet Orange Scab and Revises the Conditions for Movement of Regulated Fruit and Nursery Stock under the SOS Quarantine., NAPPO. https://pestalerts.org/official-pest-report/elsino-australis-sweet-orange-scab-aphis-establishes-quarantined-areas
NAPPO, 2021. Elsinoë australis (causal agent of Sweet Orange Scab): APHIS adds Baldwin and Mobile Counties in Alabama to the Domestic Quarantine Area., North American Plant Protection Organization Phytosanitary Alert System. https://pestalerts.org/official-pest-report/elsino-australis-causal-agent-sweet-orange-scab-aphis-adds-baldwin-and-mobile
SPC, 2008. Communication to CABI., Suva, Fiji: South Pacific Commission.
Timmer L W, Priest M, Broadbent P, Tan M K, 1996. Morphological and pathological characterization of species of Elsinoeumlaut˜ causing scab diseases of citrus. Phytopathology. 86 (10), 1032-1038. DOI:10.1094/Phyto-86-1032
Distribution MapsTop of page
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