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Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings
Dissertation (MInstAgrar)--University of Pretoria, 2008.
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University of Pretoria
2013
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| _version_ | 1867613466662010881 |
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| access_status_str | Open Access |
| author2 | Aveling, Terry A.S. |
| author_browse | Aveling, Terry A.S. |
| author_facet | Aveling, Terry A.S. |
| collection | Thesis |
| dc_rights_str_mv | © 2008 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 | Dissertation (MInstAgrar)--University of Pretoria, 2008. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/29549 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:36:35.732Z |
| 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:2263/29549 Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings Aveling, Terry A.S. Labuschagne, Nico Van der Waals, Jacqueline Elise gustore24@yahoo.fr Kalonji Kabengele Muzela, J B Stem rot Fungicides Soilborne pathogens Lettuce seedlings Root rot UCTD Dissertation (MInstAgrar)--University of Pretoria, 2008. Lettuce (Lactuca sativa L.) seedlings diseases caused by soilborne pathogens are characterised by root rot, stem rot and damping-off of the seedlings that can occur at any time during growth. Fusarium solani, Pythium ultimum and Rhizoctonia solani are known to be the important destructive pathogens of lettuce, causing severe yield losses in South Africa. The aim of this research was to evaluate the effects of three selected fungicides to control these pathogens on lettuce seedlings. In this study the fungicides metalaxyl (Apron®), fludioxonil (Celest®) and mefenoxam (Subdue®) were applied at two concentrations as single and double doses on lettuce seedlings to determine their efficacy to control the pathogens Fusarium solani, Pythium ultimum and Rhizoctonia solani after significant reduction of mycelia growth was observed in vitro. Cultures of P. ultimum (UPGH024), R. solani (UPGH122) and F. solani (UPGH122) were obtained from the culture collection of the Department of Microbiology and Plant Pathology, University of Pretoria and cultivated on PDA for 2 days at 25ºC. Pasteurised soil was artificially inoculated with these pathogens. For the first experiment lettuce seeds were planted in polystyrene seedling trays at a depth of 1.0 cm. There were four replications of 50 seeds per treatment. In Experiment 2 pots (12 cm x 7 cm) were filled with pasteurised growing medium and 3-week old seedlings were transplanted. There were three replications of six pots containing three plants each. Seedling trays and pots were drenched with fungicides and placed in a randomised block design in a controlled environment room at 20- 26°C with a 12h-light/dark regime. The seedling trays and pots were rotated daily in the room. Seedling trays and pots were watered daily to maintain field capacity. The seedlings were able to grow larger in the pots than in seedling trays. It was confirmed that the treatment with fludioxonil (Celest®) at double and single dose inhibited the growth of the three fungi F. solani, P. ultimum and R. solani on lettuce seedlings without causing phytotoxicity. All three fungicides significantly reduced the diseases caused by the three pathogens. These findings are consistent with previous reports that fludioxonil, metalaxyl and mefenoxam can control oomycete fungi. There are few registered fungicides for the control of Fusarium solani, Pythium ultimum and Rhizoctonia solani on lettuce, therefore further work will aim to confirm these results in the field. Microbiology and Plant Pathology unrestricted 2013-09-07T15:53:37Z 2008-11-27 2013-09-07T15:53:37Z 2008-09-03 2008 2008-11-18 Dissertation Kalonji Kabengele Muzela, JB 2008, Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings, MInstAgrar dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/29549 > E1218/ag http://hdl.handle.net/2263/29549 http://upetd.up.ac.za/thesis/available/etd-11182008-143858/ © 2008 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 University of Pretoria |
| spellingShingle | Stem rot Fungicides Soilborne pathogens Lettuce seedlings Root rot UCTD Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| title | Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| title_full | Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| title_fullStr | Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| title_full_unstemmed | Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| title_short | Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| title_sort | evaluation of three fungicides for control of soilborne diseases of lettuce seedlings |
| topic | Stem rot Fungicides Soilborne pathogens Lettuce seedlings Root rot UCTD |
| url | http://hdl.handle.net/2263/29549 http://upetd.up.ac.za/thesis/available/etd-11182008-143858/ |