Modeling of Photoionized Plasmas

In this paper I review the motivation and current status of modeling of plasmas exposed to strong radiation fields, as it applies to the study of cosmic X-ray sources. This includes some of the astrophysical issues which can be addressed, the ingredients for the models, the current computational tools, the limitations imposed by currently available atomic data, and the validity of some of the standard assumptions. I will also discuss ideas for the future: challenges associated with future missions, opportunities presented by improved computers, and goals for atomic data collection.Comment: 17 pages, 8 figures, to appear in the proceedings of Xray2010, Utrecht, the Netherlands, March 15-17 201

The effects of inter-crop cultivation Between rows of citrus crop on spreading of Guignardia citricarpa Ascospores and in the citrus black spot occurrence

No presente, foi avaliada a influência do amendoim-forrageiro cv. Amarillis e da gramínea coastcross nas entrelinhas de plantas de laranjeira 'Natal' quanto à produção e liberação de ascósporos de G. citricarpa, e consequente controle da mancha-preta dos frutos cítricos. Os tratamentos avaliados foram: 1- cultivo convencional, sem utilização de fungicidas; 2- cultivo convencional, com utilização de fungicidas; 3- gramínea coastcross, e 4- amendoim forrageiro entre as linhas das plantas. O monitoramento de ascósporos deu-se mediante armadilhas caça-esporos do tipo Quest Volumetric Spore System™. Um total de 33 inspeções foi realizado semanalmente, a partir do final de agosto até início de setembro do ano seguinte. A quantificação da doença deu-se mediante utilização de escala diagramática de notas, sendo também determinada a porcentagem de frutos com padrão comercial. A gramínea coastcross foi o melhor tratamento em reduzir o número de ascósporos liberados, diferindo, estatisticamente, do convencional, porém não dos demais tratamentos. Cultivo intercalar e cultivo convencional associado com aplicações de fungicida foram os mais eficientes quanto à redução da severidade de sintomas da mancha-preta, diferindo do tratamento- -testemunha, sem emprego de fungicida. Esses tratamentos foram os que também proporcionaram a maior porcentagem de frutos com padrão comercial, sendo de 89% a 91%, enquanto no cultivo convencional, sem uso de fungicidas, foi de 73%.This study highlighted the effect of planting coast-cross grass and forage peanut cv. Amarilis between rows of Natal oranges on spreading of Guignardia citricarpa ascospores and consequent citrus black spot control. Treatments evaluated were: 1- conventional cultivation, free of fungicides; 2- conventional cultivation, using protective fungicides; 3- inter-crop cultivation of coast-cross grass between rows of citrus crops and; 4- inter-cropping cultivation of forage peanut between the rows of citrus crops. Quest Volumetric Spore SystemTM traps were set in order to determine the number of ascospores released. A total of 33 inspections were conducted weekly, from the end of August until early September the following year. A diagrammatic scale was used to determine the severity of the disease as well as the percentage of fruits having a commercial standard. The coast-cross grass was more effective in reducing the number of ascospores produced, whose average statistics were lower than in the conventional treatments, free-fungicides. The inter-crop and conventional cultivation method coupled with fungicide treatment was more effective in reducing the severity of citrus black spot symptoms, and differs statistically from the fungicide-free control method. These methods also resulted in a higher percentage of fruits of a commercial standard, ranging from the 89% through the 91% percentile, and the cultivation, free of fungicides, fell within the 73%.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fazenda Sao JoseLouis Dreyfus Commodities Agroindustrial LtdaInstituto Agronômico Centro APTA Citros Sylvio MoreiraUniversidade Estadual Paulista FCAVUniversidade Estadual Paulista FCAVFAPESP: 01/10993-

Probabilistic risk-based model for the assessment of Phyllosticta citricarpa-infected citrus fruit and illicit plant material as pathways for pathogen introduction and establishment

CITATION: Gottwald, T.R. et al. (2020) Probabilistic risk-based model for the assessment of Phyllostict citricarpa-infected citrus fruit and illicit plant material as pathways for pathogen introduction and establishment. Crop Protection 142(2021):14 pages. doi.10.1016/j.cropro.2020.105521The original publication is available at: sciencedirect.comCitrus Black Spot (CBS), caused by the ascomycete, Phyllosticta citricarpa, is a fruit, foliar, and twig spotting fungal disease affecting the majority of commercial cultivars of citrus. The disease causes cosmetic lesions, may cause fruit drop and P. citricarpa is considered a quarantine pathogen by some countries, impacting domestic and international trade of citrus fruit. Regulatory requirements affecting fruit trade exist even though there is no documented case of disease spread via infected fruit into previously disease-free areas. To clarify the risk of fruit as a potential pathway for the spread of CBS, we developed a quantitative, probabilistic risk assessment model. The model provides an assessment of all steps in the fruit pathway, including production, packinghouse handling, transportation, export-import distribution channels, and consumer endpoints. The model is stochastic and uses Monte Carlo simulation to assess the risk of P. citricarpa moving through all steps in the pathway. We attempted to use all available literature and information to quantitate risk at each point in the potential pathway and by sequentially linking all steps to determine the overall quantitative risk. In addition, we assessed climatological effects on incidence of diseased fruit at production sites and on fungal reproduction and infection, as well as criteria for establishment at endpoints. We examined ten case studies between exporting and importing locations/countries. Model results indicated fruit to be an epidemiologically insignificant means for CBS spread, even between producing countries where CBS occurs and CBS-free importing countries with disease-conducive climates. We created a second model to examine the introduction of infected plant material from countries where CBS occurs. This model demonstrated significant probability of introduction via such infected material. However, pathogen establishment and disease development was still restricted only to areas with conducive climatological conditions. We created a tool to quantitatively explore the viability of various potential pathways via combinations of CBS-present production sites and corresponding pathway endpoints, including environments conducive and non-conducive to CBS. The tool is provided to aid decision makers on phytosanitary risk relative to international trade of citrus fruit.Publisher’s versio