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Fusarium circinatum is an important fungal pathogen of Pinus species utilized in commercial forestry worldwide. In Colombia, it was first found on nursery plants and later in plantations associated with basal cankers on young trees. In this study, we explored the population diversity of the pathogen in Colombia by analyzing 136 isolates collected from diseased nursery plants (2005–2007) and plantation trees (2017 and 2020). These were sourced from different geographical regions and Pinus species. Genotyping was performed using 10 microsatellite markers, while mating types were identified with PCRs targeting the MAT1 locus. Using microsatellites, a total of 33 multilocus haplotypes were detected. Genetic diversity indices showed low levels of diversity in both the overall collection and in specific collection groupings. The data also suggested that a small number of isolates had unique origins in the country (p <.05), and relatively low levels of population differentiation were detected between the nursery and plantation collections. All the isolates were scored as having the MAT1‐1 mating type, and no evidence for the random association among microsatellite alleles (p =.0001) was found. Overall, these data suggest that F. circinatum was introduced into Colombia a small number of times, likely on seed for nursery production. Furthermore, the data also indicate that the pathogen has spread from nurseries to the plantations via asexual reproduction and on asymptomatic plants. This has resulted in a highly clonal F. circinatum population in Colombia that has resulted from accidental introductions of the pathogen into a production nursery. [ABSTRACT FROM AUTHOR]

Dothistroma needle blight (DNB) caused by Dothistroma septosporum is one of the most important needle diseases of Pinus spp., especially in Southern Hemisphere plantations. In Colombia, the pathogen has caused severe outbreaks in plantations of Pinus tecunumanii of the low elevation population (LE). Currently, management strategies suffer from a lack of knowledge regarding the epidemiology of D. septosporum under tropical climatic conditions. In this study we determined the patterns of conidial dispersal and considered how climatic conditions in Colombia influence them. The study was conducted over 15 consecutive months between October 2010 and December 2011 using glass slide‐based spore traps. Conidia were found on the traps throughout the year, with the peak abundance during November to January (2010) and November to December (2011). During peak conidial production, relative humidity and temperature had the greatest influence on conidial dispersal. Favourable weather conditions in Colombia, particularly rainfall, have contributed to continuous conidial production throughout the year, leading to D. septosporum infections all year round. This high reproductive rate as a consequence of high precipitation is in contrast to other Southern Hemisphere and Northern Hemisphere countries with more specific periods of rainfall and infection. [ABSTRACT FROM AUTHOR]

Plantation forestry in Colombia is based mainly on non-native species of Pinus and Eucalyptus. Since 2008, a disease with symptoms similar to those of dothistroma needle blight ( DNB) has been found affecting large areas planted to Pinus spp. The aim of this study was to identify the causal pathogen as well as to document the levels of disease incidence and severity. Isolates from each of three forestry zones, collected from different host species, were compared based on rDNA sequence of the ITS regions. These were conclusively identified as Dothistroma septosporum, one of two Dothistroma spp. known to cause DNB. Susceptibility was greatest on low elevation Pinus tecunumanii followed by Pinus kesiya and Pinus oocarpa. Pinus maximinoi and high elevation P. tecunumanii showed tolerance to D. septosporum. The disease incidence in the different zones varied significantly with the North zone being the most severely affected. This constitutes the first report of disease distribution and susceptibility of hosts, as well as the first consideration of the relative importance of D. septosporum in Colombia. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The Antarctic peninsula and Patagonia region (the south of South America) have recently been identified as the regions with the highest gravity-wave activity in the world. In this work, the generation and propagation of gravity waves in the Patagonia region in an event of strong wave activity from 30 October 1995-1 November 1995 is examined by means of radiosonde measurements and simulations with the Weather Research and Forecasting (WRF) model. The waves are generated by strong surface winds found near the Andes mountains at a latitude of 49-51°S. The strong low-level winds are related to an extratropical cyclone that propagates southeastward in the South Pacific ocean and approaches the western coast of the continent. The waves propagate southeast toward Tierra del Fuego and they continue their propagation over the Drake Passage. They are found to propagate long meridional (lateral) distances due to the shear background conditions. This fact is corroborated with WRF simulations and a novel technique that combines wavelet analysis and backward ray-tracing. Therefore, this work provides further evidence that high gravity-wave activity found by several studies over Drake Passage may have an orographic origin. During the orographic wave event, which lasts about 72 hours, the horizontal wavelength is unexpectedly found to change day-to-day. The analysis shows that changes in the near-surface meteorological conditions produced by the cyclone passage may trigger different components of the forcing orography. The orographic waves propagate toward their critical levels, which are found at 25 km and above. The radiosonde measurements show that the wave is breaking continuously along a wide altitude range; this finding from measurements supports the picture of continuous wave erosion along the ray path instead of abrupt wave-breaking for the examined wave event. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

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-α, in addition to conidial sizes. Significant differences in resistance of clones to these pathogens were also evident from the various trials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cryphonectria canker, caused by Cryphonectria cubensis, has limited the development of new Eucalyptus plantations in tropical and subtropical regions. The pathogen is commonly found on Eucalyptus, but its occurrence on other hosts in the Myrtaceae has also been documented. In this study C. cubensis is reported as the causal agent of a serious canker disease on Tibouchina spp. (Melastomataceae) in Colombia. We used morphological studies, pathogenicity tests on Eucalyptus and Tibouchina, and a phylogenetic study using partial ribosomal DNA sequence data. This is the first record of C. cubensis on a host outside the Myrtaceae. [ABSTRACT FROM AUTHOR]

A rust disease was observed during routine disease surveys of Eucalypt species in Colombia. The cause of the disease was identified, using morphology and DNA sequence data, as the myrtle rust pathogen, Puccinia psidii. We evaluated the susceptibility of Eucalyptus grandis and the hybrid Eucalyptus urograndis to P. psidii. This is the first report of this pathogen on Corymbia citriodora and Eucalyptus species in Colombia. [ABSTRACT FROM AUTHOR]