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Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape
Thesis (MScAgric)--Stellenbosch University, 2020.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2021
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| _version_ | 1867614134693003264 |
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| access_status_str | Open Access |
| author | Lebenya, Palesa |
| author2 | Halleen, Francois |
| author_browse | Halleen, Francois Lebenya, Palesa |
| author_facet | Halleen, Francois Lebenya, Palesa |
| author_sort | Lebenya, Palesa |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2020. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/124250 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:47:13.037Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/124250 Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape Lebenya, Palesa Halleen, Francois Mostert, Lizel Stellenbosch University. Faculty of AgriSciences. Dept. of Plant Pathology. Phomopsis -- Control Grapes -- Diseases and pests Canker (Plant disease) Diaporthe Vineyards -- South Africa -- Western Cape -- Management Fungicides -- Control Leaf spots -- Etiology UCTD Thesis (MScAgric)--Stellenbosch University, 2020. ENGLISH ABSTRACT: Phomopsis cane and leaf spot (“streepvlek”) is an important grapevine disease caused by Diaporthe ampelina. An increase in “streepvlek” symptoms, including bleached canes, have been observed in Western Cape vineyards. This phenomenon has been observed on table as well as wine grapes. Several Diaporthe species have recently been isolated from internal wood necrosis associated with Phomopsis dieback in South Africa and raised the question whether other Diaporthe species are also associated with typical “streepvlek” symptoms, which might explain poor control observed in vineyards. A number of fungicides are registered in South Africa against Phomopsis, namely calcium polysulphide, copper oxychloride, copper oxychloride + sulphur, copper oxychloride+lime, folpet, mancozeb, maneb + zinc oxide, propineb and polysulphide sulphur. The fungicides used for the protective control of D. ampelina are aimed at the protection of young plant material during critical periods such as when conidia are released after prolonged rainy periods in spring. A detailed survey of vineyards in the Western Cape Province with typical “streepvlek” symptoms was performed to determine whether D. ampelina was the causative agent, or if other Diaporthe spp. are associated with these symptoms. In each vineyard, 100 grapevines were visually inspected for “streepvlek” symptoms. A total of 118 vineyards representing 32 grapevine cultivars from different regions in the Western Cape were surveyed for symptoms on green shoots and leaves. Forty-eight vineyards representing 19 cultivars were surveyed for bleached cane symptoms from the same regions. Symptomatic shoots were collected and taken to the laboratory where isolations were conducted. Diaporthe-like isolates were first identified using D. ampelina species-specific PCR primers (D. amp_F1/D. amp_ R2), and for a representative sub-sample of isolates, the internal transcribed spacer region (ITS1, 5.8S rRNA, and ITS2) and the beta-tubulin (tub2) were sequenced to confirm the results. Most symptoms were observed in the Durbanville, Stellenbosch and Somerset West areas, with Shiraz and Cabernet Sauvignon being the most susceptible cultivars. Diaporthe ampelina was associated with 100% of the typical cane and leaf spot symptoms as well as bleached canes and is undoubtedly the causal organism of Phomopsis cane and leaf spot in the Western Cape. Since there was, an increase in “streepvlek” symptoms, including bleached canes in the Western Cape during the survey, a study was conducted to determine if the fungicides used to control the disease was still effective. Firstly, in vitro sensitivity of D. ampelina against a selection of registered fungicides was assessed. Secondly, the effectiveness of mancozeb, folpet and maneb + zinc oxide in the laboratory on detached Bukkettraube shoots against artificial spray inoculation of D. ampelina conidia was evaluated, and thirdly, the effectiveness of mancozeb, folpet and maneb + zinc oxide in the field on Bukettraube and Cabernet Sauvignon vineyards against natural infection was evaluated. The field treatments were applied three times, the first at bud break, then after every seven days. The EC50 values for the seven fungicides tested in vitro indicated that mancozeb and folpet were more effective at lower concentrations in suppressing the growth of D. ampelina. In the detached shoots assay, folpet and mancozeb contained infection by D. ampelina to 23.08%, and maneb + zinc oxide to 34.62% on the leaves. On shoots, folpet contained infection to 5.77%, mancozeb to 11.54% and maneb +zinc oxide to 38.46%. In the field, on the Cabernet Sauvignon shoots, folpet and mancozeb contained infection to 8.3% and 5.5%, respectively, significantly better than maneb + zinc oxide (16.7%), although the maneb + zinc oxide treatment was significantly less than in the control treatment (77.8%). In the Bukettraube vineyard the three fungicide treatments resulted in similar disease incidences on the shoots, namely 0% for folpet and mancozeb and 8.3% for maneb +zinc oxide. These were significantly lower than in the water control (36.1%). Results from the in vitro assay, detached shoots, as well as field trials clearly showed that Phomopsis cane and leaf spot can be controlled by fungicides currently registered in South Africa. The perceived lack of control in industry or by farmers may be due to incorrect application and timing of fungicides. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Masters 2021-12-02T12:56:45Z 2022-02-22T10:20:01Z 2021-12-02T12:56:45Z 2020-12 Thesis http://hdl.handle.net/10019.1/124250 en_ZA Stellenbosch University 92 pages : illustrations (some color) application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Phomopsis -- Control Grapes -- Diseases and pests Canker (Plant disease) Diaporthe Vineyards -- South Africa -- Western Cape -- Management Fungicides -- Control Leaf spots -- Etiology UCTD Lebenya, Palesa Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape |
| title | Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape |
| title_full | Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape |
| title_fullStr | Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape |
| title_full_unstemmed | Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape |
| title_short | Etiology and control of Phomopsis cane and leaf spot of grapevines in the Western Cape |
| title_sort | etiology and control of phomopsis cane and leaf spot of grapevines in the western cape |
| topic | Phomopsis -- Control Grapes -- Diseases and pests Canker (Plant disease) Diaporthe Vineyards -- South Africa -- Western Cape -- Management Fungicides -- Control Leaf spots -- Etiology UCTD |
| url | http://hdl.handle.net/10019.1/124250 |
| work_keys_str_mv | AT lebenyapalesa etiologyandcontrolofphomopsiscaneandleafspotofgrapevinesinthewesterncape |