Chrysoporthe zambiensis detected on native Syzygium in Zimbabwe L. Jimu 1 & N. Muzhinji 2 & C. Magogo 1 & E. Mureva 1 Received: 8 May 2017 /Accepted: 11 December 2017 /Published online: 19 December 2017 # Australasian Plant Pathology Society Inc. 2017 Abstract Fruiting bodies similar to those of Chrysoporthe were observed on Syzygium guineense in Bindura, Zimbabwe. The objective of this study was to identify the fungus and to test its pathogenicity on Eucalyptus. BLAST searches and phylogenetic analyses of the ITS, BT1 and BT2 gene regions identified the fungus as Chrysoporthe zambiensis. This study represents the first report of this fungus in Zimbabwe and on native Syzygium. The presence and high pathogenicity of C. zambiensis presents a potential threat on Eucalyptus plantations in Zimbabwe. Keywords Cryphonectriaceae . Eucalyptus . Host range expansion . Pathogenicity . Stem pathogen . Tree disease Myrtaceae are widespread in Africa, where some species are native while others were introduced as ornamentals, fruits and plantations. The most dominant and widespread native Myrtaceae are Syzygium species for example S. cordatum and S. guineense (e.g. Maroyi 2008). Introduced species are dominated by eucalypts that have been domesticated in most countries in Africa. As such, eucalypt plantations are established in areas that were previously occupied by native forests, sharing boundaries with native Myrtaceae. Where there is poor management, stumps left when land is cleared sometimes coppice, leading to a mixture of native Myrtaceae and eucalypt species in a plantation. Establishment of eucalypt plantations in areas that were previously occupied or adjacent to native Myrtaceae increases the risk of enemies such as pathogens and pests extending their hosts that may end up detrimental to either species. Host range expansions by such enemies are highly likely be- cause native and introduced hosts share a similar internal en- vironment that makes either of them susceptible to enemies of their relatives (De Vienne et al. 2009). Some of the most serious pathogens of eucalypts worldwide are thought to have emerged from related native hosts in areas where they were domesticated. Highly cited examples of such pathogens are Puccinia psidii and Chrysoporthe species, the causal patho- gens of Myrtle rust and stem cankers, respectively (e.g. Slippers et al. 2005; Graça et al. 2013). A good example is C. austroafricana, a fungus that is thought to be native on Syzygium species in southern Africa where it is thought to have extended its host range to cause stem cankers on euca- lypts (Slippers et al. 2005). During a disease survey in Zimbabwe’ s Eucalyptus plantations and native Syzygium,a fungus resembling those in the genus Chrysoporthe was ob- served on S. guineense. The aim of this study was to identify this fungus and to assess its potential threat to Eucalyptus plantations in Zimbabwe. Disease surveys on native Myrtaceae were conducted from November to December 2016 in Bindura, Zimbabwe. Fruiting bodies similar to those of Chrysoporthe were observed on dying stems and branches of S. guineense. Diseased trees were observed along rivers and in wetlands. Surveys conducted on S. cordatum did not show any disease symptoms. Diseased bark and branch material were sampled, placed in sampling bags and taken to the laboratory for isolation. Diseased plant materials were placed in moist chambers to induce sporulation after which the isolation was done by lifting spore drops from fruiting structures with a sterile needle and transferring these to MEA (20 g/l malt extract, 15 g/l agar). Single spore cultures were incubated at 25 °C for six days to obtain sufficient my- celium for DNA extraction. Isolates are maintained in the culture collection (PPRI) of the National Collection of Fungi, South Africa. Mycelia were scrapped from the cultures and macerated under liquid nitrogen. DNA was extracted using the modified CTAB protocol (Doyle and Doyle 1987). About 200 mg mycelia were ground using liquid nitrogen in * L. Jimu jimaldino@yahoo.com 1 Department of Natural Resources, Bindura University of Science Education, P. Bag, 1020 Bindura, Zimbabwe 2 Zimbabwe Tobacco Research Board, Harare, Zimbabwe Australasian Plant Disease Notes (2018) 13: 1 https://doi.org/10.1007/s13314-017-0285-y