TheEucalyptuscanker pathogenChrysoporthe cubensisdiscovered in eastern Australia

Abstract

Chrysoporthe cubensis is an important pathogen of commercially planted Eucalyptus species (Myrtaceae) in tropical and subtropical parts of the world where these trees are planted as non-natives. Although the majority of Eucalyptus spp. are native to Australia, Chr. cubensis is not common there and has been reported only once from naturally growing Eucalyptus marginata in Western Australia. Chr. cubensis is able to infect hosts in the Myrtaceae and Melastomataceae other than Eucalyptus, but has not been found on hosts other than Eucalyptus in Australia. Recently, fruiting structures resembling those of Chr. cubensis were discovered on Tibouchina heteromalla, planted as a non-native in the Botanical Gardens in Cairns, northern Queensland. These fruiting structures and resulting isolates were characterised as Chr. cubensis in this study. Pathogenicity studies found that Corymbia spp., including commercially important spotted gum, are susceptible along with E. pilularis and E. dunnii. The discovery of Chr. cubensis on a non-native plant in the northern part of Australia is important as it might imply that the pathogen has been introduced into the country and pose a significant threat to native Eucalyptus forests. Alternatively, this fungus might occur naturally in the area on hosts other than Tibouchina, possibly Eucalyptus or related species, and that Australia forms part of its native range.