Coniothyrium stem canker, caused by Teratosphaeria zuluensis, is one of the most important diseases of plantation-grown Eucalyptus trees in tropical and subtropical areas of the world. Previous research on the population structure of T. zuluensis in China, Malawi and South Africa has suggested that T. zuluensis in these countries had independent origins, with the highest genetic diversity found in a population from South China. In this study, the genetic diversity of three T. zuluensis populations from different regions in South China was determined using ten microsatellite markers. Results showed that more than one genotype of T. zuluensis can occur on a single tree in all three populations and that a moderate to high genetic diversity exists within the populations. Population differentiation was evident between populations, and in one population there was evidence for a low level of genetic recombination. Comparisons among the three populations of T. zuluensis from South China suggest that they originated independently of each other.

Among fungi in the Cryphonectriaceae, Cryphonectria parasitica, the causal agent of chestnut blight, and Chrysoporthe spp., inducing stem cankers and death of plantation-grown Eucalyptus spp., constitute some of the most important tree pathogens. During a survey to determine diseases and related pathogens associated with native and non-native Myrtales in Zambia, two fungi resembling stem canker pathogens in the genus Chrysoporthe were recovered from Syzygium guineense and Eucalyptus grandis. We undertook this study to characterise the fungi, using DNA sequence comparisons and morphological features. Inoculation tests were also conducted in a greenhouse to assess their pathogenicity on Eucalyptus spp. Results showed distinct phenotypic differences between isolates collected from Zambia and existing species of Chrysoporthe, and phylogenetic analyses demonstrated that the Zambian isolates represent previously undescribed species of Chrysoporthe. These isolates, which have been named Chrysoporthe zambiensis sp. nov. and Chrysoporthe syzygiicola sp. nov., are only known from their anamorphic states. Both species were found to be pathogenic to Eucalyptus. The description of Chr. zambiensis and Chr. syzygiicola with teleomorph names, led to the new combination Chrysoporthe hodgesiana for the only anamorphic species in Chrysoporthe, Chrysoporthella hodgesiana, to ensure more stable and less confusing taxonomy for Chrysoporthe.

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Fire has been used to prepare land during tree plantation establishment for many years but uncertainty about how ecosystems respond to prescribed burning makes it difficult to predict the effects of fire on soil nutrients. The aim of this study was to determine the effect of burning accumulated forest residues (slash) on soil chemical properties and how trees respond. We analyzed 40 burned and unburned sites and compared growth of Eucalyptus grandis W. Hill ex Maiden between sites. Soil pH increased by 39% after fire, suggesting reduced soil acidity and increased liming. Total nitrogen increased by 100%; other nutrients (Ca 2? , Mg 2? and K ?) also increased. Increase in nutrients had a significant effect on the growth of E. grandis; larger and taller trees were associated more with burned than unburned sites. This study provides evidence that burning accumulated slash during land preparation prior to plantation establishment alters soil nutrient status and enhances the growth of E. grandis.

Abstract• Plantation forestry in Zambia is based mainly on non-native Eucalyptus and Pinus species and constitutes an important component of the country's economy. The productivity of these plantations is, however, threatened by several factors, including fungal pathogens that reduce timber quality and cause tree mortality.• In this paper we present a review of diseases affecting plantation forestry and highlight factors that may favour their development and severity in the country.• Plantation health management in Zambia is seriously hampered by a general lack of information on pests and diseases affecting these plantations. In this regard, most research has been done more than 30 years ago, and very few pathogens have been identified to species level using modern identification techniques.• Recent surveys identified several previously unknown diseases of Eucalyptus spp. in the country, emphasizing the importance of renewed research on this topic. The impact of diseases associated with these pathogens has been exacerbated by poor plantation management, insufficient financial resources and lack of human capacity to deal with them.• Successful plantation management in Zambia will require increased and improved training of foresters regarding tree health issues, more effective quarantine, silvicultural practices, and importantly, the establishment of sound breeding and selection programmes. These will require considerable commitment from Government, commercial companies and research and educational organizations in the country.

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