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Epidemiology of early blight on potatoes in South Africa
Thesis (DPhil (Plant Pathology))--University of Pretoria, 2006.
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University of Pretoria
2013
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| _version_ | 1867613562819575808 |
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| access_status_str | Open Access |
| author2 | Korsten, Lise |
| author_browse | Korsten, Lise |
| author_facet | Korsten, Lise |
| collection | Thesis |
| dc_rights_str_mv | © 2004, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (DPhil (Plant Pathology))--University of Pretoria, 2006. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/24541 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:38:07.678Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/24541 Epidemiology of early blight on potatoes in South Africa Korsten, Lise upetd@ais.up.sc.za Van der Waals, Jacqueline Elise Disease forecaster Decision support system Spore dispersal Genetic diversity Survey Rams Solanum tuberosum Alternaria solani UCTD Thesis (DPhil (Plant Pathology))--University of Pretoria, 2006. Early blight (Alternaria solani Sorauer)is a major foliar disease of potatoes in most growing regions of the world and is underestimated in South Africa. This project studies the epidemiology and control of the disease in South Africa. A decision support system (DSS) for early blight in South Africa was developed and evaluated in field trials. This early blight DSS is the first such system to be developed in South Africa and once incorporated with the late blight model, will represent innovative technology for use in the South African potato industry. Trends in weather variables and concentrations of airborne conidia of A. solani were monitored. Distinct seasonal variation was noted. Peaks in spore concentration coincided with periods favourable for spore formation and dispersal; most notable was diurnal periodicity and interrupted wetting periods. The results obtained from these measurements will be useful in improving early blight DSSs for southern Africa. Isolates of A. solani from various potato-growing regions in South Africa were characterized using virulence, vegetative compatibility (VC) and random amplified microsatellite (RAMS) primers. Neither the virulence assays nor VC tests sufficiently characterised the population. Analysis of RAMS profiles revealed 27% genetic diversity among the isolates. This value is similar to diversity values obtained by previous authors studying A. solani, however, it is relatively high for an asexually reproducing fungus. There was no evidence for geographical clustering of isolates, indicating that isolates are widespread across South Africa. A survey on control practices and grower perceptions of early blight in South Africa was conducted using a questionnaire. These questionnaires were distributed to growers from 10 potato-growing regions in South Africa. Results highlighted the most popular control methods and cultivars in the South African potato industry. The majority of respondents indicated that they would use an accurate, cost-effective early blight DSS, and that more research is necessary on early blight in South Africa. A survey on control practices and grower perceptions of early blight in South Africa was conducted using a questionnaire. These questionnaires were distributed to growers from 10 potato-growing regions in South Africa. Results highlighted the most popular control methods and cultivars in the South African potato industry. The majority of respondents indicated that they would use an accurate, cost-effective early blight DSS, and that more research is necessary on early blight in South Africa. Estimated crop losses ranged from 1% - 60%, with an average of approximately 20%. This is the first comprehensive epidemiological study to be conducted on early blight in South Africa and has highlighted the need for further research. Microbiology and Plant Pathology unrestricted 2013-09-06T17:55:44Z 2005-05-20 2013-09-06T17:55:44Z 2004-03-24 2006-05-20 2005-05-11 Thesis Van der Waals, J 2004, Epidemiology of early blight on potatoes in South Africa, DPhil thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/24541 > http://hdl.handle.net/2263/24541 http://upetd.up.ac.za/thesis/available/etd-05112005-125046/ © 2004, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Disease forecaster Decision support system Spore dispersal Genetic diversity Survey Rams Solanum tuberosum Alternaria solani UCTD Epidemiology of early blight on potatoes in South Africa |
| title | Epidemiology of early blight on potatoes in South Africa |
| title_full | Epidemiology of early blight on potatoes in South Africa |
| title_fullStr | Epidemiology of early blight on potatoes in South Africa |
| title_full_unstemmed | Epidemiology of early blight on potatoes in South Africa |
| title_short | Epidemiology of early blight on potatoes in South Africa |
| title_sort | epidemiology of early blight on potatoes in south africa |
| topic | Disease forecaster Decision support system Spore dispersal Genetic diversity Survey Rams Solanum tuberosum Alternaria solani UCTD |
| url | http://hdl.handle.net/2263/24541 http://upetd.up.ac.za/thesis/available/etd-05112005-125046/ |