The pitch canker pathogen Fusarium circinatum has caused devastation to Pinus spp. in natural forests and non-natives in commercially managed plantations. This has drawn attention to the potential importance of Fusarium species as pathogens of forest trees. In this study, we explored the diversity of Fusarium species associated with diseased Pinus patula, P. tecunumanii, P. kesiya and P. maximinoi in Colombian plantations and nurseries. Plants displaying symptoms associated with a F. circinatum-like infection (i.e., stem cankers and branch die-back on trees in plantations and root or collar rot of seedlings) were sampled. A total of 57 isolates were collected and characterised based on DNA sequence data for the translation elongation factor 1-α and β-tubulin gene regions. Phylogenetic analyses of these data allowed for the identification of more than 10 Fusarium species. These included F. circinatum, F. oxysporum, species within the Fusarium solani species complex and seven novel species in the Fusarium fujikuroi species complex (formerly the Gibberella fujikuroi species complex), five of which are described here as new. Selected isolates of the new species were tested for their pathogenicity on Pinus patula and compared with that of F. circinatum. Of these, F. marasasianum, F. parvisorum and F. sororula displayed levels of pathogenicity to P. patula that were comparable with that of F. circinatum. These apparently emerging pathogens thus pose a significant risk to forestry in Colombia and other parts of the world.

Fusarium circinatum, the causal agent of pine pitch canker (PPC), is currently one of the most important threats of Pinus spp. globally. This pathogen is known in many pine-growing regions, including natural and planted forests, and can affect all life stages of trees, from emerging seedlings to mature trees. Despite the importance of PPC, the global distribution of F. circinatum is poorly documented, and this problem is also true of the hosts within countries that are affected. The aim of this study was to review the global distribution of F. circinatum, with a particular focus on Europe. We considered (1) the current and historical pathogen records, both positive and negative, based on confirmed reports from Europe and globally; (2) the genetic diversity and population structure of the pathogen; (3) the current distribution of PPC in Europe, comparing published models of predicted disease distribution; and (4) host susceptibility by reviewing literature and generating a comprehensive list of known hosts for the fungus. These data were collated from 41 countries and used to compile a specially constructed geo-database. A review of 6297 observation records showed that F. circinatum and the symptoms it causes on conifers occurred in 14 countries, including four in Europe, and is absent in 28 countries. Field observations and experimental data from 138 host species revealed 106 susceptible host species including 85 Pinus species, 6 non-pine tree species and 15 grass and herb species. Our data confirm that susceptibility to F. circinatum varies between different host species, tree ages and environmental characteristics. Knowledge on the geographic distribution, host range and the relative susceptibility of different hosts is essential for disease management, mitigation and containment strategies. The findings reported in this review will support countries that are currently free of F. circinatum in implementing effective procedures and restrictions and prevent further spread of the pathogen.

Calonectria (Ca.) species and their Cylindrocladium (Cy.) anamorphs are well-known pathogens of forest nursery plants in subtropical and tropical areas of the world. An investigation of the mortality of rooted Pinus cuttings in a commercial forest nursery in Colombia led to the isolation of two Cylindrocladium anamorphs of Calonectria species. The aim of this study was to identify these species using DNA sequence data and morphological comparisons. Two species were identified, namely one undescribed species, and Cy. gracile, which is allocated to Calonectria as Ca. brassicae. The new species, Ca. brachiatica, resides in the Ca. brassicae species complex. Pathogenicity tests with Ca. brachiatica and Ca. brassicae showed that both are able to cause disease on Pinus maximinoi and P. tecunumanii. An emended key is provided to distinguish between Calonectria species with clavate vesicles and 1-septate macroconidia.

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Chrysoporthe cubensis is one of the most serious canker pathogens on commercially grown Eucalyptus species in the tropics and subtropics. During recent surveys for native hosts of C. cubensis in Colombia, fungi with fruiting structures similar to those of C. cubensis were found on native Miconia theaezans and Miconia rubiginosa, both members of the Melastomataceae. These fungi were identified based on morphology and DNA sequences of the ITS1/ITS2 region of the rDNA operon and the β‐tubulin genes. The majority of isolates from M. theaezans and M. rubiginosa grouped together with South American C. cubensis isolates from Eucalyptus species and Syzygium aromaticum (clove). However, some of the isolates from M. theaezans grouped with isolates of Chrysoporthella hodgesiana, another anamorph species linked to Chrysoporthe, from Tibouchina spp. in Colombia. Pathogenicity of these fungi was assessed on various Melastomataceae. Miconia rubiginosa was more susceptible to infection by C. cubensis than two Eucalyptus clones. Isolates of C. cubensis and Chrysop. hodgesiana were mildly pathogenic on the various hosts included in the pathogenicity trials, and most pathogenic on Tibouchina urvilleana and Tibouchina lepidota.

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Pitch canker, caused by the ascomycete fungus Fusarium circinatum, infects a wide range of Pinus species. The pathogen has a global distribution and limits plantation productivity wherever susceptible Pinus species are commercially cultivated. During 2005During -2007 symptoms typical of those associated with F. circinatum were observed in Colombia on nursery seedlings of P. maximinoi, P. tecunumanii and P. patula, as well as established P. patula and P. kesiya trees in plantations. Symptoms on seedlings included collar and root disease while shoot dieback and resinous stem cankers were found on trees in plantations.The aim of this study was to isolate and identify the causal agent of these symptoms and to evaluate the relative tolerance of various families of Pinus species commonly grown in Colombia. By making use of morphology and DNA-based methods, as well as pathogenicity tests on P. patula seedlings, it was possible to show that the symptoms observed in the nursery and field were caused by F. circinatum. Furthermore, the results of pathogenicity tests with two virulent isolates of the pathogen indicated that P. tecunumanii from lowelevation sources and P. maximinoi are significantly more tolerant to infection by F. circinatum than P. tecunumanii from high-elevation sources and P. patula. These results show that there is substantial opportunity to avoid losses due to infection by F. circinatum through deployment of resistant planting stock.2

The identities of Botryosphaeriaceae causing cankers on Eucalyptus in Colombia were investigated using morphological and DNA sequence comparisons. The pathogenicity of the species was also assessed on 42 Eucalyptus grandis clones planted at four different sites. Two species of the Botryosphaeriaceae were found to occur on E. grandis in Colombia. Neofusicoccum ribis was the more common species, and also the most pathogenic. Botryosphaeria dothidea was found only in one zone of Colombia, and was also less pathogenic than N. ribis. These two species could be distinguished easily based on DNA sequences of the ITS1 ⁄ ITS2 rDNA region and EF1-a, in addition to conidial sizes. Significant differences in resistance of clones to these pathogens were also evident from the various trials.