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1.
For Ecol Manage ; 536: 120847, 2023 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-37193248

RESUMEN

European forests are threatened by increasing numbers of invasive pests and pathogens. Over the past century, Lecanosticta acicola, a foliar pathogen predominantly of Pinus spp., has expanded its range globally, and is increasing in impact. Lecanosticta acicola causes brown spot needle blight, resulting in premature defoliation, reduced growth, and mortality in some hosts. Originating from southern regions of North American, it devastated forests in the USA's southern states in the early twentieth century, and in 1942 was discovered in Spain. Derived from Euphresco project 'Brownspotrisk,' this study aimed to establish the current distribution of Lecanosticta species, and assess the risks of L. acicola to European forests. Pathogen reports from the literature, and new/ unpublished survey data were combined into an open-access geo-database (http://www.portalofforestpathology.com), and used to visualise the pathogen's range, infer its climatic tolerance, and update its host range. Lecanosticta species have now been recorded in 44 countries, mostly in the northern hemisphere. The type species, L. acicola, has increased its range in recent years, and is present in 24 out of the 26 European countries where data were available. Other species of Lecanosticta are largely restricted to Mexico and Central America, and recently Colombia. The geo-database records demonstrate that L. acicola tolerates a wide range of climates across the northern hemisphere, and indicate its potential to colonise Pinus spp. forests across large swathes of the Europe. Preliminary analyses suggest L. acicola could affect 62% of global Pinus species area by the end of this century, under climate change predictions. Although its host range appears slightly narrower than the similar Dothistroma species, Lecanosticta species were recorded on 70 host taxa, mostly Pinus spp., but including, Cedrus and Picea spp. Twenty-three, including species of critical ecological, environmental and economic significance in Europe, are highly susceptible to L. acicola, suffering heavy defoliation and sometimes mortality. Variation in apparent susceptibility between reports could reflect variation between regions in the hosts' genetic make-up, but could also reflect the significant variation in L. acicola populations and lineages found across Europe. This study served to highlight significant gaps in our understanding of the pathogen's behaviour. Lecanosticta acicola has recently been downgraded from an A1 quarantine pest to a regulated non quarantine pathogen, and is now widely distributed across Europe. With a need to consider disease management, this study also explored global BSNB strategies, and used Case Studies to summarise the tactics employed to date in Europe.

2.
Plant Dis ; 93(10): 1079, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30754353

RESUMEN

In November of 2007, dieback symptoms (basal needle dieback, wilting, and dieback of terminal shoot) were observed on plant groups of Pinus radiata and P. pinaster in a tree nursery located in Anadia in the central region of Portugal (40°26'N, 08°23'W). Two containers with a total of 112 plants per pine species (with and without symptoms) were collected. Small pieces (5 mm long; two from the roots, stem at the soil level, and the aerial part, totaling six pieces) of 20 symptomatic plants were sterilized with 3% sodium hypochlorite, and isolations were performed on potato dextrose agar (PDA) supplemented with 0.5 mg/ml of streptomycin sulfate. A species of Fusarium was isolated from all infected tissues and pure cultures were obtained by single hyphal tip transfers on PDA and Spezieller Nährstoffarmer agar and incubated at 25°C for 10 days with a 12-h photoperiod. The species was identified as Fusarium circinatum Nirenberg & O'Donnell (= F. subglutinans Wollenweb & Reinking) on the basis of morphological and cultural characteristics (2). They produced white, aerial mycelia, violet pigment, typically three-septate macroconidia with slightly curved walls, single-celled microconidia, and characteristic sterile, coiled hyphae. Microconidia were ovoid or allantoid and born in false heads on aerial polyphialides. The identification was confirmed by PCR with specific primers CIRC1A/CIRC4A, resulting in a 360-bp DNA fragment of the two nuclear ribosomal intergenic spacer regions (3). Pathogenicity tests were performed by inoculating 5- and 9-month-old P. pinaster and P. radiata seedlings, respectively. Plants belonging to P. pinea species (8-month-old), the second most important pine in the country, were also included in the tests. Small strips of bark (10 × 1 mm) were cut from the stems and similar-sized pieces of PDA colonized by two isolates of F. circinatum were placed in contact with the open wounds and covered with Parafilm. Ten seedlings for each pine species, isolate, and control (with sterile PDA) were provided in a total of 90 plants. First symptoms, basal needle and shoot dieback, were observed in P. radiata 8 days after inoculation. One month later, all P. radiata and 70% of the P. pinaster plants were dead. In all P. pinea plants, needles turned red along the main stem, from center to periphery, but only 2% of these plants presented wilting of the terminal shoot after 1 month. No symptoms were observed on control seedlings. F. circinatum was reisolated from symptomatic plants of the three species tested. To our knowledge, this is the first report of F. circinatum in Portugal. Pitch canker, caused by Gibberella circinata (anamorph F. circinatum), is one of the most aggressive pathogens on several pine species in the world (1). In 2005, the fungus was detected in the European continent affecting P. radiata and P. pinaster in northern Spain. References: (1) E. Landeras et al. Plant Dis. 89:1015, 2005. (2) H. I. Niremberg and K. O'Donnell. Mycologia 90:434, 1998. (3) W. Schweigkofler et al. Appl. Environ. Microbiol. 70:3512, 2004.

3.
Artículo en Inglés | MEDLINE | ID: mdl-25019721

RESUMEN

We study the physics of quantum phase transitions from the perspective of nonequilibrium thermodynamics. For first-order quantum phase transitions, we find that the average work done per quench in crossing the critical point is discontinuous. This leads us to introduce the quantum latent work in analogy with the classical latent heat of first order classical phase transitions. For second order quantum phase transitions the irreversible work is closely related to the fidelity susceptibility for weak sudden quenches of the system Hamiltonian. We demonstrate our ideas with numerical simulations of first, second, and infinite order phase transitions in various spin chain models.


Asunto(s)
Transición de Fase , Teoría Cuántica , Simulación por Computador , Modelos Teóricos , Termodinámica
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