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The genus Chrysoporthe includes important pathogens of plantation-grown Eucalyptus spp. and has been reported from several tree genera in the order Myrtales in tropical and subtropical areas of the world. During disease surveys in South China, fruiting structures typical of Chrysoporthe spp. were observed on cankers on Eucalyptus spp. and Syzygium cumini trees. The aim of this study was to confirm the identity of the Chrysoporthe cubensis infecting the Eucalyptus spp. and S. cumini and to test the pathogenicity of the fungus. Following glasshouse trials to select virulent isolates, field inoculations were undertaken to screen different commercial Eucalyptus genotypes for their susceptibility to the fungus. Isolates were characterized based on their morphology and DNA sequence data for the 13-tubulin and internal transcribed spacer regions of the ribosomal DNA. Results showed that the putative pathogen represented the Asian form of C. cubensis, which occurred on numerous different Eucalyptus spp. and hybrid clones as well as S. cu,nini. Field inoculations showed that all six of the Eucalyptus genotypes tested are susceptible to infection by C. cubensis. Significant differences were observed between them, providing prospects to select disease-tolerant planting stock in the future. [ABSTRACT FROM AUTHOR]

Many species in the Cryphonectriaceae cause diseases of trees, including those in the genera Eucalyptus and Syzygium. During disease surveys on these trees in southern China, fruiting structures typical of fungi in the Cryphonectriaceae and associated with dying branches and stems were observed. Morphological comparisons suggested that these fungi were distinct from the well known Chrysoporthe deuterocubensis, also found on these trees in China. The aim of this study was to identify these fungi and evaluate their pathogenicity to Eucalyptus clones/species as well as Syzygium cumini. Three morphologically similar fungal isolates collected previously from Indonesia also were included in the study. Isolates were characterized based on comparisons of morphology and DNA sequence data for the partial LSU and ITS nuclear ribosomal DNA, β-tubulin and TEF-1α gene regions. After glasshouse trials to select virulent isolates field inoculations were undertaken to screen different commercial Eucalyptus clones/species and S. cumini trees for susceptibility to infection. Phylogenetic analyses showed that the Chinese isolates and those from Indonesia reside in a clade close to previously identified South African Celoporthe isolates. Based on morphology and DNA sequence comparisons, four new Celoporthe spp. were identified and they are described as C. syzygii, C. eucalypti, C. guangdongensis and C. indonesiensis. Field inoculations indicated that the three Chinese Celoporthe spp., C. syzygii, C. eucalypti and C. guangdongensis, are pathogenic to all tested Eucalyptus and S. cumini trees. Significant differences in the susceptibility of the inoculated Eucalyptus clones/species suggest that it will be possible to select disease-tolerant planting stock for forestry operations in the future.