Title page for ETD etd-11192008-091812

Document Type Master's Dissertation
Author Halueendo, Keumbo Lorna Maija Ester
Email Halueendo@hotmail.com
URN etd-11192008-091812
Document Title Impact assessment of citrus black spot, Guignardia Citricarpa kiely, in southern Africa and an alternative approach in management strategies
Degree MInstAgrar
Department Microbiology and Plant Pathology
Advisor Name Title
Dr T Regnier Co-Supervisor
Prof L Korsten Supervisor
  • citrus black spot
  • Guignardia Citricarpa
  • South Africa
  • Mozambique
  • Swaziland
  • Zimbabwe
  • Namibia
  • southern African countries
Date 2008-09-03
Availability unrestricted

Citrus black spot (CBS) caused by Guignardia citricarpa is responsible for economic losses in Southern African countries such as South Africa, Mozambique, Swaziland, Zimbabwe and Namibia. Black spot is considered to be a phytosanitary disease for the European Union and the United States of America markets. Exporters to these countries incur losses throughout the supply chain due to phytosanitary restrictions. For these reasons, the occurrence and management practices of CBS and its impact on growers in Southern Africa were investigated through a survey using a questionnaire. In the study, it was found that when CBS was present it was primarily managed by using chemicals and general orchard sanitation. In addition, growers in some of the surveyed countries or production regions follow spraying programs that are based on disease forecasting models and this practice has proven very effective in managing the disease. Furthermore, furfural, a sugarcane waste product was assessed for its efficacy in controlling G. citricarpa. The efficacy of the product as a contact or a fumigant was demonstrated in vitro and in vivo on fresh leaves, leaf litter and fruit lesions as well as in soil. A molecular study, using a Polymerase Chain Reaction protocol was conducted to assess the survival of the pathogen in the soil after exposure to furfural. The product however only proved efficient under natural conditions. The non-target effect of furfural on the soil micro-flora was also assessed. The product proved suitable for soil applications as it is not phytotoxic and has minimal non-target effects on bacterial populations. Furfural proved to control G. citricarpa, by breaking the life cycle, thus reducing the disease incidence. The application of furfural on a larger scale (irrigation or spraying) will therefore improve the control of CBS in developing countries.

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.

Please cite as follows:

Halueendo, KLME 2008, Impact assessment of citrus black spot, Guignardia Citricarpa kiely, in southern Africa and an alternative approach in management strategies, MInstAgrar dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11192008-091812/ >

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