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Several key tree genera are used in planted forests worldwide, and these represent valuable global resources. Planted forests are increasingly threatened by insects and microbial pathogens, which are introduced accidentally and/or have adapted to new host trees. Globalization has hastened tree pest emergence, despite a growing awareness of the problem, improved understanding of the costs, and an increased focus on the importance of quarantine. To protect the value and potential of planted forests, innovative solutions and a better-coordinated global approach are needed. Mitigation strategies that are effective only in wealthy countries fail to contain invasions elsewhere in the world, ultimately leading to global impacts. Solutions to forest pest problems in the future should mainly focus on integrating management approaches globally, rather than single-country strategies. A global strategy to manage pest issues is vitally important and urgently needed.

AIM : Cryptic species in the Neofusicoccum parvum–N. ribis species complex have only recently been described, invalidating previous interpretations on host and geographical distribution. This study aimed to characterize the diversity and distribution of these species and to understand the patterns of host associ- ation, likely origins and their patterns of spread. LOCATION : Australia, Brazil, Cameroon, Chile, China, Colombia, Ethiopia, France, Greece, India, Indonesia, Iran, Italy, Japan, Kenya, Mexico, New Zealand, Panama, Portugal, Puerto Rico, South Africa, South Korea, Spain, Swaziland, Taiwan, Thailand, Uganda, United States of America, Uruguay, Zambia and Zimbabwe. METHODS : Using the unique polymorphisms that separate species within the complex, we evaluated sequence search results available in public and in our own databases. In addition, the global distribution of diversity of N. parvum was analysed using seven microsatellite markers. RESULTS : Neofusicoccum parvum is found in 90 hosts across six continents and 29 countries. Neofusicoccum kwambonambiense is found on four continents, six countries and on 14 hosts; N. occulatum is found on four continents, four countries and on 11 hosts; N. umdonicola is found on two continents, countries and hosts; N. cordaticola is found on three continents, countries and hosts; N. batangarum is found on two continents, three countries and three hosts; and N. ribis is found on one host in one country. Population genetic analysis of the global N. parvum population reflects admixture and repeat introductions. MAIN CONCLUSIONS : This study illustrates the unfettered and frequent movement of latent pathogens across international borders. Amongst the species in the N. parvum–N. ribis complex, N. parvum is the most widespread and has been reported on the majority of the hosts studied. The current dispersal of N. par- vum and its sister species is probably due to repeated introductions of plant material into new growing areas, with Eucalyptus and Vitis vinifera being two prominent candidates for material transfer.

A canker and wilt disease caused by the fungal pathogen Ceratocystis manginecans has devastated Acacia mangium plantations in Southeast Asia. The disease develops when the pathogen enters wounds of the stems of the trees. The wounds are caused by wind damage, branch pruning, animal feeding and borer infestation. Various insects, including nitidulid beetles and scolytine wood borers, have been shown to be closely associated with the development of this disease, although a vector relationship has not been established. The disease has never been found on the roots of trees and isolations from soil in heavily infested plantations have failed to yield cultures of C. manginecans. Research was initiated in 2012 has focused on developing an inoculation protocol to select A. mangium with tolerance to infection by C. manginecans. In order to achieve this, an isolate of the pathogen identified using DNA sequencing technology and having a high level of aggressiveness was selected. Preliminary trials showed that inoculations need to be conducted on established trees with welldeveloped vascular tissues, ideally one-year-old, and that tests on small plants are meaningless. The ideal inoculation technique involved inserting a single plug of C. manginecans mycelia into wounds made on the stems of one-year-old trees and monitoring the results during the subsequent 12 months, at which time most trees would have died. Over a period of approximately eight years, inoculations were performed on 6 000 such trees representing 140 A. mangium families. The small number of surviving trees was retained by grafting and subsequent vegetative propagation. Re-inoculation of these putatively tolerant trees has led to the identification of approximately 50 clones having high levels of disease tolerance. These trees can now be used to establish seed orchards and for hybridisation with Acacia auriculiformis, which is known to be substantially less susceptible to C. manginecans than A. mangium. The results suggest that it may be possible to pursue plantation forestry utilising A. mangium, most likely as a hybrid partner with A. auriculiformis.

BACKGROUND : Proteins in the Glycoside Hydrolase family 32 (GH32) are carbohydrate-active enzymes known as invertases that hydrolyse the glycosidic bonds of complex saccharides. Fungi rely on these enzymes to gain access to and utilize plant-derived sucrose. In fungi, GH32 invertase genes are found in higher copy numbers in the genomes of pathogens when compared to closely related saprophytes, suggesting an association between invertases and ecological strategy. The aim of this study was to investigate the distribution and evolution of GH32 invertases in the Ceratocystidaceae using a comparative genomics approach. This fungal family provides an interesting model to study the evolution of these genes, because it includes economically important pathogenic species such as Ceratocystis fimbriata, C. manginecans and C. albifundus, as well as saprophytic species such as Huntiella moniliformis, H. omanensis and H. savannae. RESULTS : The publicly available Ceratocystidaceae genome sequences, as well as the H. savannae genome sequenced here, allowed for the identification of novel GH32-like sequences. The de novo assembly of the H. savannae draft genome consisted of 28.54 megabases that coded for 7 687 putative genes of which one represented a GH32 family member. The number of GH32 gene family members appeared to be related to the ecological adaptations of these fungi. The pathogenic Ceratocystis species all contained two GH32 family genes (a putative cell wall and a putative vacuolar invertase), while the saprophytic Huntiella species had only one of these genes (a putative cell wall invertase). Further analysis showed that the evolution of the GH32 gene family in the Ceratocystidaceae involved transposable element-based retro-transposition and translocation. As an example, the activity of a Fot5-like element likely facilitated the assembly of the genomic regions harbouring the GH32 family genes in Ceratocystis. CONCLUSIONS : This study provides insight into the evolutionary history of the GH32 gene family in Ceratocystidaceae. Our findings suggest that transposable elements shaped the evolution of the GH32 gene family, which in turn determines the sucrolytic activities and related ecological strategies of the Ceratocystidaceae species that harbour them. The study also provides insights into the role of carbohydrate-active enzymes in plant-fungal interactions and adds to our understanding of the evolution of these enzymes and their role in the life style of these fungi.

The purpose of this study was to test the hypothesis that Chrysoporthe cubensis on native trees in South America could be the source of the pathogen that causes severe stem cankers and often mortality in commercially propagated Eucalyptus trees. This was done by investigating populations originating from two adjacent Eucalyptus (Myrtaceae) plantations in Colombia, and wild Miconia rubiginosa trees (Melastomataceae) growing alongside these stands. Polymorphic microsatellite markers were used to quantify allele sizes in 20 and 39 isolates from the two Eucalyptus stands and 32 isolates from adjacent M. rubiginosa trees. Gene and genotypic diversities were calculated from these data, and population differentiation and assignment tests were performed to ascertain whether the populations were genetically different. Results showed that there were no differences between any of the populations using these techniques, and that they can be treated as a single population. Therefore, the results support the hypothesis that host switching has occurred in C. cubensis in Colombia.

Species of Botryosphaeria are among the most serious pathogens that affect mango trees and fruit. Several species occur on mangoes, and these are identified mainly on the morphology of the anamorphs. Common taxa include Dothiorella dominicana, D. mangiferae (= Natrassia mangiferae), D. aromatica and an unidentified species, Dothiorella 'long'. The genus name Dothiorella, however, is acknowledged as a synonym of Diplodia. This study aimed to characterize and name the Botryosphaeria spp. associated with disease symptoms on mangoes. To achieve this isolates representing all four Dothiorella spp. mentioned above were compared with the anamorphs of known Botryosphaeria spp., based on conidial morphology and DNA sequence data. Two genomic regions were analyzed, namely the ITS rDNA and beta-tubulin regions. The morphological and molecular results confirmed that the fungi previously identified from mango as species of Dothiorella belong to Fusicoccum. Dothiorella dominicana isolates were identical to isolates of F. parvum (teleomorph = B. parva). A new epithet, namely F. mangiferum, is proposed for isolates previously treated as D. mangiferae or N. mangiferae. Isolates of D. aromatica were identified as F. aesculi (teleomorph = B. dothidea). A fourth Fusicoccum sp. also was identified as those isolates previously known as Dothiorella 'long'. A key is provided to distinguish these species based on anamorph morphology in culture. This study provides a basis for the identification of Botryosphaeria species from mango, which is important for disease control and to uphold quarantine regulations.Species of Botryosphaeria are among the most serious pathogens that affect mango trees and fruit. Several species occur on mangoes, and these are identified mainly on the morphology of the anamorphs. Common taxa include Dothiorella dominicana, D. mangiferae (= Natrassia mangiferae), D. aromatica and an unidentified species, Dothiorella 'long'. The genus name Dothiorella, however, is acknowledged as a synonym of Diplodia. This study aimed to characterize and name the Botryosphaeria spp. associated with disease symptoms on mangoes. To achieve this isolates representing all four Dothiorella spp. mentioned above were compared with the anamorphs of known Botryosphaeria spp., based on conidial morphology and DNA sequence data. Two genomic regions were analyzed, namely the ITS rDNA and beta-tubulin regions. The morphological and molecular results confirmed that the fungi previously identified from mango as species of Dothiorella belong to Fusicoccum. Dothiorella dominicana isolates were identical to isolates of F. parvum (teleomorph = B. parva). A new epithet, namely F. mangiferum, is proposed for isolates previously treated as D. mangiferae or N. mangiferae. Isolates of D. aromatica were identified as F. aesculi (teleomorph = B. dothidea). A fourth Fusicoccum sp. also was identified as those isolates previously known as Dothiorella 'long'. A key is provided to distinguish these species based on anamorph morphology in culture. This study provides a basis for the identification of Botryosphaeria species from mango, which is important for disease control and to uphold quarantine regulations.

Development of improved Eucalyptus genotypes involves the routine identification of breeding stock and superior clones. Currently, microsatellites and random amplified polymorphic DNA markers are the most widely used DNA-based techniques for fingerprinting of these trees. While these techniques have provided rapid and powerful fingerprinting assays, they are constrained by their reliance on gel or capillary electrophoresis, and therefore, relatively low throughput of fragment analysis. In contrast, recently developed microarray technology holds the promise of parallel analysis of thousands of markers in plant genomes. The aim of this study was to develop a DNA fingerprinting chip for Eucalyptus grandis and to investigate its usefulness for fingerprinting of eucalypt trees. A prototype chip was prepared using a partial genomic library from total genomic DNA of 23 E. grandis trees, of which 22 were full siblings. A total of 384 cloned genomic fragments were individually amplified and arrayed onto glass slides. DNA fingerprints were obtained for 17 individuals by hybridizing labeled genome representations of the individual trees to the 384-element chip. Polymorphic DNA fragments were identified by evaluating the binary distribution of their background-corrected signal intensities across full-sib individuals. Among 384 DNA fragments on the chip, 104 (27%) were found to be polymorphic. Hybridization of these polymorphic fragments was highly repeatable (R2>0.91) within the E. grandis individuals, and they allowed us to identify all 17 full-sib individuals. Our results suggest that DNA microarrays can be used to effectively fingerprint large numbers of closely related Eucalyptus trees.

Fusarium solani is a fungal pathogen that infects many different genera of plants. It represents one of the two Fusarium spp. commonly isolated from agricultural soils and plant tissues in Ethiopia. To determine the diversity of F. solani in Ethiopia, we studied 43 isolates using Amplified Fragment Length Polymorphism (AFLP) and nucleotide sequences of the Translation Elongation Factor 1α (TEF-1α) and β-tubulin genes. TEF-1α sequences from GenBank, representing previously described species and clades of the F. solani-Haematonectria haematococca complex, were also included for comparative purposes. Phylogenetic analyses of the TEF-1α data separated the isolates into three groups corresponding with the three previously described clades (Clades 1–3) for this fungus. The Ethiopian isolates aggregated into one group corresponding to Clade 3. TEF-1α, β-tubulin and AFLPs further separated the Ethiopian isolates into a number of clusters and apparently novel phylogenetic lineages. Although the biological and ecological significance of these lineages and clusters is unclear, our data show that the Ethiopian agricultural environment is rich in species and lineages of the F. solani-H. haematococca complex.

Pitch canker, caused by the fungus Fusarium circinatum , is one of the most important pathogens of Pinus species. Sporadic outbreaks and epidemics caused by this fungus have been reported from numerous countries. Symptoms differ depending on the host species, geographical region, climatic conditions and associated insects. Pitch canker represents a significant threat to countries where non-native and susceptible Pinus spp. are grown intensively in plantations. A thorough understanding of the ecology and epidemiology of the causal agent is an important prerequisite to managing this threat. The aim of this review is to summarise contemporary knowledge relating to the pitch canker pathogen, with a particular focus on its threat to plantation forestry.

Cryphonectria cubensis causes a destructive canker disease of Eucalyptus species. Management of this disease is primarily through breeding and selection of disease resistant trees. One means of selecting such trees is by artificial inoculation with the pathogen. In routine screening trials in South Africa, an isolate of C. cubensis, considered to be highly pathogenic, has been used for such inoculations. Although the most resistant clones under natural conditions are the same as those detected in inoculation trials, a question has arisen whether all clones respond similarly to different C. cubensis isolates. Thus, a trial consisting of five clones, known to differ in susceptibility to infection by C. cubensis, was established. These trees were inoculated with nine South African C. cubensis isolates previously shown to differ in pathogenicity. Inoculations showed a significant isolate × clone interaction as well as an “apparent immunity” for one clone × isolate interaction, providing evidence highly suggestive of a vertical resistance component in the pathosystem. Disease screening in this pathosystem has traditionally relied on a single pathogen isolate; however, considering data presented here, future reliance on a single isolate may be inadequate. Cryphonectria canker is caused by the ascomycetous fungus Cryphonectria cubensis. This disease causes severe losses to Eucalyptus trees, which are widely planted as exotics in plantation in tropical and subtropical parts of the world. The most effective means used to reduce losses due to Cryphonectria canker is achieved through breeding and selection of disease tolerant clones and hybrids. For this reason, effective and reasonably rapid disease screening procedures are important. Our study focused on evaluating the commonly used screening procedure for resistance to Cryphonectria canker in South Africa. This procedure typically uses a single highly pathogenic isolate for inoculation and subsequent identification of disease resistant clones. Results of this study showed that disease resistance screening should preferably be undertaken using more than one isolate of C. cubensis. However, results also show that the isolate that has been used in the past produced relatively reliable results. Overall, results of this study have shown evidence suggestive of vertical resistance in the C. cubensis-Eucalyptus pathosystem, and they have contributed to an improved understanding of one of the most important Eucalyptus diseases in South Africa.