Cryphonectria canker on Tibouchina in South Africa

Cryphonectria cubensis is an important canker pathogen of plantation Eucalyptus spp. in tropical and sub-tropical areas of the world, including South Africa. It is best known on Eucalyptus spp., but it also occurs on Syzygium aromaticum (clove). In 1998, C. cubensis was found to cause cankers on the non-myrtaceous hosts Tibouchina urvilleana and T. lepidota in Colombia. In this study, we report on a similar canker disease that has recently been found in South Africa on T. granulosa commonly grown as an ornamental tree. The identity of the pathogen was determined through morphological comparisons and phylogenetic analyses of ITS and β-tubulin gene sequences. The pathogenicity of the fungus was also tested on T. granulosa and E. grandis. Morphological as well as DNA sequence comparisons showed that the fungus on T. granulosa is the same as C. cubensis occurring on Eucalyptus spp. in South Africa. Pathogenicity tests on T. granulosa and E. grandis clones showed that the fungus from T. granulosa is able to cause cankers on both hosts.