Journal of Pure and Applied MicrobiologyVol. 2 No. 2

Investigation of Ampelomyces sp. Associated with Twig Yellowing in Southern and Eastern Namibia Occurring on Namibian Acacia erioloba

P.M. Chimwamurombe¹ and L. Kanyomeka²*

¹Department of Biological Sciences, Faculty of Science, University of Namibia, Private Bag 13301, 340 Mandume Ndemufayo Avenue, Windhoek, Namibia. ²Crop Science Department, Faculty of Agriculture and Natural Resources, University of Namibia, Ogongo Campus, Private Bag 5520, Oshakati, Namibia

Received on 06 August 2008 and accepted on 16 September 2008

 

ABSTRACT

Acacia tree species are the most common tree in Namibia. This is probably because they are better adapted to the arid conditions that predominate in Namibia. Acacia karoo, Acacia mellifera, Acacia hebeclada, Acacia erioloba, Acacia luderitzii and Acacia hereroense are some of the commonest species encountoured. The Acacia erioloba species (Camelthorn) is easily noticed for its large and shady canopy. Traditionally, Acacia species are used by several indigenous people to treat minor ailments, whereas nowadays most people grow it for its shade and it also grows to become large and beautiful scenic plant. In the recent years these trees have been attacked by yellowing dieback diseases, which is threatening their existence. The aim of this study was to investigate the identity of the causal agents of twig yellowing diseases dieback that was recently observed on Acacia erioloba species in southern and eastern Namibian farms. Identification of pathogenic agents is an important dedicated step to finding remedial ways to any phytopathological problem. Previous morphological work in our laboratory had shown that the causal agent was a fungus. In this study fresh diseased twig were sampled and pure single spore cultures were made. From these pure cultures DNA was extracted and used in an internal transcribed spacer (ITS) PCR. The PCR products were purified and sequenced. The sequences were used in BLAST searches to interrogate the Genbank and high sequence similarity of 99% was obtained with Ampelomyces sp.. From this work we conclude that Ampelomyces sp. is associated with Acacia erioloba dieback and that confirmation by Koch’s postulates will be the next step in order to determine the virulence and pathogenicity of the Ampelomyces sp. isolates that have been collected so far.

Keywords : Acacia erioloba, Ampelomyces sp. pathogen, dieback, internal transcribed spacer region.