Forestry in South Africa
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June : Vepris, Zanthoxylum and Clausena species

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22 June, 2012


I would very much appreciate help locating specimens of the native trees Vepris, Zanthoxylum and Clausena spp.  As part of the DST/NRF Centre of Excellence in Tree Health Biotechnology, we are doing research on various diseases of citrus and we believe that one of these "Candidatus Liberibacter africanus" might have native African hosts.  Some background is as follows:

"Candidatus Liberibacter africanus" is the causative agent of citrus greening disease in South Africa. This bacterium has only been identified from Africa, Reunion Island and Mauritius and may have evolved on the African continent along with indigenous members of the Rutaceae (Citrus family). Our study aims to determine whether this bacterium or a related bacterium occurs naturally within members of this family and to determine whether it affects healthy indigenous plants.

We would like to analyze leaf samples from especially Vepris lanceolata (Witysterhout/White Ironwood), Zanthoxylum capense (Klein Perdepram/Small forest knobwood) and Clausena anisata (Perdepis/Horsewood) or other species in these three genera or other members of the Rutaceae. We would appreciate it if either:

  1. leaf samples of these specimens can be sent to us, or
  2. the localities (latitude longitude coordinates from a GPS or from Google earth or detailed directions) of specimens can be sent to us or
  3. if you are available on any of the dates below whether you would be prepared to accompany us to any specimens. 

We will be collecting from Nkwalini up to Tshaneni, Swaziland
during the 9th to 11th of July and Mpumulanga and Limpopo from the 11th to 14th of July.

If you are able to help and could send me samples, please collect leaf samples from each tree separately into a plastic bag. About 20-30 leaves should suffice. Please close the plastic bag carefully so samples do not mix and label it with a unique number. Please add the following information regarding the sample; Location (lat/long coordinates of specimen, collector's name, date of collection and species of specimen. Please keep the bags cool without freezing them until you can send them to us. Please send by priority mail or courier, addressed to Ms. Ronel Viljoen or Prof. G. Pietersen, ARC-PPRI and FABI at Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria, 0002. Courier costs will be covered by us and must be arranged prior to samples being sent. If uncertain regarding any aspect please contact Ronel Viljoen at

Thank you in anticipation for your help.

Ronel Viljoen
MSc Student
Department of Microbiology and Plant Pathology
University of Pretoria