Diseases associated with Botryosphaeriaceae are widespread in Eucalyptus plantations in southern China. A high species diversity of Botryosphaeriaceae exists in these plantations, including species in the genera Botryosphaeria, Cophinforma, Lasiodiplodia, and Neofusicoccum. Botryosphaeriaceae fungi isolated from Eucalyptus and adjacent plants can be pathogenic to Eucalyptus trees. However, few field studies have assessed the tolerance of Eucalyptus genotypes to Botryosphaeriaceae. Twenty-two isolates representing 14 Botryosphaeriaceae species identified from Eucalyptus and adjacent plants were inoculated on the seedlings of a widely planted Eucalyptus genotype in a greenhouse. The greenhouse inoculation results showed that most isolates of Lasiodiplodia species were more pathogenic than the isolates of Botryosphaeria, Cophinforma, and Neofusicoccum species. Based on the greenhouse inoculation results, five highly pathogenic isolates, including one isolate of L. hormozganensis, two isolates of L. pseudotheobromae, and two isolates of L. theobromae were inoculated on trees of 20 Eucalyptus genotypes in the field to evaluate the tolerance of these genotypes. The resistance of the 20 Eucalyptus genotypes to each of the five Lasiodiplodia isolates was variable. The average lesion lengths produced by the five Lasiodiplodia isolates on each of the 20 Eucalyptus genotypes indicated that there were significant differences in tolerance among the Eucalyptus genotypes. This study evaluated the tolerance levels of 20 Eucalyptus genotypes, that are widely planted in southern China, to highly pathogenic Botryosphaeriaceae species.
