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Effect of Different Foliar Fertilizer Applications on Esca Disease of Grapevine: Symptom Expression and Nutrient Content in the Leaf and Composition of the Berry
No full textEsca disease, the most common grapevine wood disease in Europe, causes yield losses correlated with the foliar symptoms’ expression. In two vineyards located in the Abruzzo Region of Italy, each of which were investigated for esca symptoms after 1994, different applications of macro- and microelements were performed in two consecutive growing seasons. The main aim of the work consisted of verifying the effects of the fertilizer applications on the foliar symptoms’ expression, in order to deepen knowledge of the nature of the symptom, which is still unclear. For each treatment, in each year, the leaf content of macro- and microelements and the composition of berries and musts were assessed. The effects of these applications on vegetative growth and yield quantity were also verified. The trials were carried out on symptomatic, asymptomatic and
apparently healthy vines. All applications, in particular those with microelements, increased the foliar symptoms’ expression, and a greater vegetative growth was detected only in vines treated with NPK fertilizers. The symptoms’ increase was always associated in the leaf with a decrease of calcium, and to a lesser extent, magnesium, reinforcing the hypothesis of the plant’s hypersensitive reaction in the development of foliar symptoms, given the role of calcium in the defense response. The vineyards were in nutritional balance regardless of the fertilizer applications. The general increase in foliar symptoms and the decrease in sugars in the musts of asymptomatic treated vines underlined the importance of the vegetative-productive balance, in Esca infected vineyards especially, in order to limit the symptoms’ expression and the decrease in yield
Effects of fosetyl Al treatments on grapevine plants in esca management
No full textEsca is the most severe and widespread grapevine wood disease. Although foliar symptom expression is not correlated with vine wood deterioration because of the intermittent nature of esca leaf symptom, the loss of production is associated with foliar symptom expression being diseased asymptomatic vines able to produce grapes with similar characteristics to grapes from healthy vines. Foliar symptoms seem to be associated with transport of toxins from infected wood to leaves. A reduction in esca symptom severity was observed in many-year trials applying commercial formulations of fosetyl Al either before or soon after the appearance of esca in vineyards properly managed and following the plan for downy mildew control. Moreover, a reduction of the average length of internal necrosis following inoculations with vascular esca pathogens and treated by fosetyl Al was noticed in potted vines. Investigations were carried out in order to explain the activity of fosetyl Al towards esca and associated pathogens. Physiological parameters of potted plants were measured: net photosynthetic rates of infected untreated plants were depressed by 20-50% for 24-60 hours after treatment compared to infected untreated ones. Foliar total proteins were extracted and tested by spectrophotometric analyses. In infected treated leaves chitobiosidase and glucosaminidase activities increased from 3 to 9 days after treatment, glucanase activity was enhanced at the third day and lypoxigenase activity increased over the time at pH 6.5, compared to untreated leaves. No differences in trans-resveratrol and ε-viniferin contents were found in the wood of treated and untreated vines. Results were discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effects of grapevine applications of fosetyl-aluminium formulations for downy mildew control on “esca” and associated fungi.
Get PDFEsca of grapevine is a fungal disease with a complex aetiology that is common in almost all regions of the world where grapes are cultivated. Despite much research, no effective control of the disease has been found. We investigated possible activity of fosetyl-aluminium (fosetyl-Al), an active ingredient in many fungicides against downy mildew, to inhibit development of esca in grapevine and the main pathogens linked to the disease, Phaeomoniella chlamydospora (Pch) and Phaeoacremonium aleophilum (Pal). In greenhouse experiments conducted on vines artificially inoculated with Pch or Pal, we found a reduction in necrosis in the woody tissue. In field experiments conducted over several years statistically significant reductions in the annual and cumulative incidence of the disease symptoms, and in cumulative vine mortality, were seen. The effect of fosetyl-Al treatments on leaf gas exchange, levels of resveratrol and ε-viniferin in the wood, and enzymatic activities were also studied. Hypotheses regarding the mechanism of action of fosetyl-Al against esca are outlined, and the possible use of products containing the chemical, applied on foliage to control downy mildew, is discussed as a strategy for control of esca
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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