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Two species of eucalypt stem canker pathogens in the genus Teratosphaeria are known from Africa. Teratosphaeria zuluensis (as Coniothyrium zuluense) was described from Eucalyptus species in South Africa in the 1990s (Wingfield et al. 1996) and T. gauchensis was reported from the continent in 2006 when a multi-gene phylogenetic study of T. zuluensis isolates, including ones previously collected from Ethiopia and Uganda (Gezahgne et al. 2005), revealed the presence of a second species (then treated as Colletogloeopsis gauchensis) causing similar symptoms on eucalypts (Cortinas et al. 2006). To date, only T. zuluensis has been recorded from South Africa. During routine disease surveys of eucalypt plantations, symptoms resembling those caused by Teratosphaeria stem canker pathogens (Figure 1) were observed in two areas, including on a host from which the disease was not previously recorded in South Africa. The first observation was made from Eucalyptus grandis trees in the Limpopo province (2017), and the second observation from E. grandis × E. nitens hybrid trees in the KwaZulu-Natal province (2022). Multi-gene DNA sequencing of the ITS and TEF gene regions identified isolates obtained from bark samples as T. gauchensis. DNA sequence data of a representative isolate were deposited in GenBank (Accession Nos. PX453255 and PX672354 for ITS and TEF, respectively). The pathogenicity of three T. gauchensis isolates, two from Limpopo (CMW 62273, CMW 62274) and one from KwaZulu-Natal (CMW 62275) was assessed on approximately 18-month-old E. grandis trees by inoculating agar plugs (5 mm) from actively growing cultures into the stems of three trees per isolate. Sterile agar plugs were used as controls. After 7 weeks, small lesions developed for the T. gauchensis isolates, while no lesions developed on the controls (Figure 2). The pathogen was reisolated from the lesions, while no isolates were obtained from the controls. This is the first report of T. gauchensis from South Africa. It was previously known only from north-eastern Africa (Ethiopia, Kenya and Uganda) and more recently from Zimbabwe (Jimu, Wingfield, et al. 2015). Based on population genetic studies it has been suggested that the pathogen could have been introduced into Zimbabwe before spreading to Uganda and Ethiopia, most likely through trade in Eucalyptus seed (Jimu, Kemler, et al. 2015; Jimu et al. 2016). The close geographic proximity of South Africa to Zimbabwe, especially the first site where the pathogen was detected in the Limpopo province in 2017, suggests possible natural spread of the pathogen via spores, especially since there has been limited to no known trade in seed from Zimbabwe to South Africa in recent years. The detection of two closely related species of Teratosphaeria stem canker pathogens in South Africa requires further studies into the relative impact of each species. Tree breeding programmes may be impacted if trees respond differently in their tolerance to the two pathogen species. The authors thank the Tree Protection Cooperative Programme for financial support and University of Pretoria for facilities.