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Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa
Thesis (MScConsEcol)--Stellenbosch University, 2025.
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867614064398565376 |
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| access_status_str | Open Access |
| author | Atkins, Sydney |
| author2 | Aylward, Janneke |
| author_browse | Atkins, Sydney Aylward, Janneke |
| author_facet | Aylward, Janneke Atkins, Sydney |
| author_sort | Atkins, Sydney |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScConsEcol)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132049 |
| institution | Stellenbosch University (South Africa) |
| last_indexed | 2026-06-10T12:46:06.004Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132049 Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa Atkins, Sydney Aylward, Janneke Roets, Francois Wingfield, Brenda Wingfield, Michael J. Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. Cupressaceae -- Diseases and pests Canker (Plant disease) Pathogenic fungi -- Genetic aspects Cypress -- South Africa Fungal diseases of plants Cypress -- Southern Hemisphere UCTD Thesis (MScConsEcol)--Stellenbosch University, 2025. Atkins, S. 2025. Atkins. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch Univeristy [online]. Available: https://scholar.sun.ac.za/items/cc07a47d-f81f-427b-bd51-3dfac3a7b79d ENGLISH ABSTRACT: Cypress canker is a severe fungal disease affecting Cupressaceae trees, caused by various species within the genus Seiridium. First discovered in 1927 in California, where it devastated Monterey cypress (Hesperocyparis macrocarpa), the disease has since spread globally across North and South America, Europe, Africa, Australia, and New Zealand. The primary means of long-distance spread is through human-mediated transport of infected plant material, while short-distance dispersal occurs predominantly via rain and wind. Historically, only three species (S. cardinale, S. cupressi, and S. unicorne) were recognized as causing cypress canker. However, taxonomic reassessment expanded this to seven species, including S. cancrinum, S. kenyanum, S. neocupressi, and S. pseudocardinale. Despite extensive research in the Northern Hemisphere, understanding cypress canker in the Southern Hemisphere, particularly in South Africa, has been limited, with the last significant study conducted around 30 years ago. This prompted a comprehensive survey to document the occurrence, pathogenicity, and genetic diversity of the disease in South Africa. Diseased material was sampled from Cupressaceae trees in various regions of South Africa. Samples were also obtained from CMW culture collection and FABI, University of Pretoria. Isolates were analysed to determine the occurrence of Seiridium pathogens, after which a pathogenicity trial was performed using the three most prevalent species in the country (S. cardinale, S. neocupressi and S. unicorne). The study identified five known pathogens (S. cancrinum, S. cardinale, S. kenyanum, S. neocupressi, and S. unicorne), with S. cardinale and S. unicorne being most prevalent. Seiridium cardinale was predominantly found in the Western Cape, with S. neocupressi being found sporadically, yet limited to the Western Cape. Seiridium unicorne was prevalent in Gauteng and the Free State. Additionally, the pathogenicity trial revealed high virulence for S. cardinale and S. neocupressi, with S. unicorne showing variable pathogenicity. Seiridium cardinale was determined to be the most prevalent species in South Africa. Genetic analysis of S. cardinale populations in South Africa indicated significant variability, suggesting multiple introductions from California, New Zealand, Chile, and Europe. This study as well as previous studies were unable to detect linkage disequilibrium in California, indicating sexual reproduction. Additionally, linkage disequilibrium was also absent in the Greece population, suggesting a new population to be sexually reproducing, however, this is likely the result of low sampling intensity. The study provided significant insights into the genetic diversity, migration, and pathogenicity of some of these fungi. The study also highlights the importance of developing stringent quarantine measures and improved monitoring of the movement of plant material to prevent further dissemination of Seiridium species. AFRIKAANSE OPSOMMING: Sipreskanker is 'n ernstige swamsiekte wat Cupressaceae-bome aantas, en word veroorsaak deur verskeie spesies binne die genus Seiridium. Die siekte is eers in 1927 in Kalifornië ontdek, waar dit Monterey-sipres (Hesperocyparis macrocarpa) verwoes het, en het sedertdien wêreldwyd oor Noord- en Suid-Amerika, Europa, Afrika, Australië en Nieu-Seeland versprei. Die primêre manier van langafstandverspreiding is deur mensbemiddelde vervoer van besmette plantmateriaal, terwyl kortafstandverspreiding hoofsaaklik deur reën en wind plaasvind. Histories is slegs drie spesies (S. cardinale, S. cupressi en S. unicorne) erken as die oorsaak van sipreskanker. Taksonomiese hersiening het dit egter uitgebrei na sewe spesies, insluitend S. cancrinum, S. kenyanum, S. neocupressi en S. pseudocardinale. Ten spyte van uitgebreide navorsing in die Noordelike Halfrond, is die begrip van sipreskanker in die Suidelike Halfrond, veral in Suid-Afrika, beperk, met die laaste betekenisvolle studie wat sowat 30 jaar gelede gedoen is. Dit het gelei tot 'n omvattende opname om die voorkoms, patogenisiteit en genetiese diversiteit van die siekte in Suid-Afrika te dokumenteer. Siekte materiaal is gemonster van Cupressaceae-bome in verskeie streke van Suid-Afrika. Monsters is ook verkry vanaf CMW-kultuurversameling en FABI, Universiteit van Pretoria. Isolate is ontleed om die voorkoms van Seiridium-patogene te bepaal, waarna 'n patogenisiteitsproef uitgevoer is met die drie mees algemene spesies in die land (S. cardinale, S. neocupressi en S. unicorne). Die studie het vyf bekende patogene geïdentifiseer (S. cancrinum, S. cardinale, S. kenyanum, S. neocupressi en S. unicorne), met S. cardinale en S. unicorne wat die meeste voorkom. Seiridium cardinale is oorwegend in die Wes-Kaap gevind, met S. neocupressi wat sporadies gevind is, maar tog beperk tot die Wes-Kaap. Seiridium unicorne was algemeen in Gauteng en die Vrystaat. Daarbenewens het die patogenisiteitproef hoë virulensie vir S. cardinale en S. neocupressi geopenbaar, met S. unicorne wat veranderlike patogenisiteit toon. Seiridium cardinale is vasgestel as die mees algemene spesie in Suid-Afrika. Genetiese ontleding van die S. cardinale-bevolkings in Suid-Afrika het beduidende variasie aangedui, wat veelvuldige invoere uit Kalifornië, Nieu-Seeland, Chili en Europa voorstel. Hierdie studie sowel as vorige studies was nie in staat om koppelingsonewewig in Kalifornië op te spoor nie, wat seksuele voortplanting aantoon. Boonop was koppelingsonewewig ook afwesig in die Griekeland-bevolking, wat daarop dui dat 'n nuwe populasie seksueel voortplant, maar dit is waarskynlik die gevolg van lae steekproef-intensiteit. Die studie het die patogeen se aanpasbaarheid by verskeie omgewingstoestande en gashere uitgelig, wat siektebestuurpogings kan bemoeilik. Masters 2025-05-21T07:00:29Z 2025-05-21T07:00:29Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132049 Stellenbosch University x, 72 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Cupressaceae -- Diseases and pests Canker (Plant disease) Pathogenic fungi -- Genetic aspects Cypress -- South Africa Fungal diseases of plants Cypress -- Southern Hemisphere UCTD Atkins, Sydney Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa |
| title | Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa |
| title_full | Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa |
| title_fullStr | Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa |
| title_full_unstemmed | Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa |
| title_short | Assessing the threat of cypress canker pathogens on Cupressaceae hosts in South Africa |
| title_sort | assessing the threat of cypress canker pathogens on cupressaceae hosts in south africa |
| topic | Cupressaceae -- Diseases and pests Canker (Plant disease) Pathogenic fungi -- Genetic aspects Cypress -- South Africa Fungal diseases of plants Cypress -- Southern Hemisphere UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132049 |
| work_keys_str_mv | AT atkinssydney assessingthethreatofcypresscankerpathogensoncupressaceaehostsinsouthafrica |