Discovery of the Eucalyptus canker pathogen Chrysoporthe cubensis on native Miconia (Melastomataceae) in Colombia

Chrysoporthe cubensis is one of the most serious canker pathogens on commercially grown Eucalyptus species in the tropics and subtropics. During recent surveys for native hosts of C. cubensis in Colombia, fungi with fruiting structures similar to those of C. cubensis were found on native Miconia theaezans and Miconia rubiginosa , both members of the Melastomataceae. These fungi were identified based on morphology and DNA sequences of the ITS1/ITS2 region of the rDNA operon and the β-tubulin genes. The majority of isolates from M. theaezans and M. rubiginosa grouped together with South American C. cubensis isolates from Eucalyptus species and Syzygium aromaticum (clove). However, some of the isolates from M. theaezans grouped with isolates of Chrysoporthella hodgesiana , another anamorph species linked to Chrysoporthe , from Tibouchina spp. in Colombia. Pathogenicity of these fungi was assessed on various Melastomataceae. Miconia rubiginosa was more susceptible to infection by C. cubensis than two Eucalyptus clones . Isolates of C. cubensis and Chrysop. hodgesiana were mildly pathogenic on the various hosts included in the pathogenicity trials, and most pathogenic on Tibouchina urvilleana and Tibouchina lepidota .