Taxonomy and pathogenicity of Ceratocystis species on Eucalyptus trees in South China, including C. chinaeucensis sp. nov.

Commercial plantations of Eucalyptus species have been established in South China, especially during the past 20 years, to meet the needs of a rapidly growing national economy. As part of a survey of fungal diseases affecting Eucalyptus species in South China, Ceratocystis species were collected from Eucalyptus plantations in the GuangDong Province. The aims of this study were to identify these Ceratocystis isolates and to test their pathogenicity to Eucalyptus . The most aggressive isolates were also used to screen different species and clones of Eucalyptus for susceptibility to infection under field conditions. The fungi were identified based on morphology and through comparisons of DNA sequence data of the ITS, partial β-tubulin and TEF-1α gene regions. Morphological and DNA sequence comparisons showed that isolates collected from Chinese Eucalyptus plantations represent two species, C . acaciivora in the C . fimbriata s . l . species complex and a previously undescribed species belonging to the C . moniliformis s . l . species complex, for which the name C . chinaeucensis sp. nov. is provided. In pathogenicity trials, both C . acaciivora and C . chinaeucensis gave rise to lesions on wounded Eucalyptus trees, and the former fungus was most pathogenic. Differences were also observed in the responses of different Eucalyptus clones to inoculation and this could be useful in reducing disease, if C . acaciivora should emerge as a pathogen in the future.