1,721,013 research outputs found
Le popolazioni di Erysiphe necator
No full textCapitolo 4 in sintesi
• Gli studi genetici sulle popolazioni di E. necator hanno ricevuto un grande impulso a partire dalla metà degli anni ‘90;
• Diversi studi hanno portato alla definizione di una “teoria dei biotipi”, che inizialmente distingueva un genotipo “I” (corrispondente a un biotipo germogli a bandiera) e di un genotipo “III” (corrispondente a un biotipo ascospore), morfologicamente indistinguibili, sessualmente incompatibili e caratterizzati da un diverso comportamento epidemico;
• Successivi studi hanno permesso di classificare le linee clonali in due gruppi (A e B), il primo caratterizzato da una minore variabilità rispetto al secondo e da svernamento come micelio nelle gemme anziché come cleistotecio;
• Ricerche condotte sia in Italia che in altre zone viticole hanno ottenuto risultanti contrastanti con la teoria dei biotipi;
• In Emilia-Romagna è stata dimostrata la presenza prevalente di isolati del genotipo B, la capacità di tutti gli isolati di causare germogli bandiera e la non specificità dei genotipi rispetto alla modalità di svernamento
Development and evaluation of a model that predicts grapevine anthracnose caused by elsino€e ampelina
No full textGrapevine anthracnose caused by Elsino€e ampelina is a serious threat in many vineyards, and its control requires repeated application of fungicides, usually on a calendar basis. A better understanding of the pathogen life cycle would help growers manage anthracnose more safely and effectively. After conducting a systematic literature search of grape anthracnose, we used the retrieved information and data to develop a mechanistic model based on systems analysis. The model simulates production and maturation of primary inoculum, infection caused by both primary and secondary conidia, and lesion formation and production of secondary inoculum. The model was validated for its ability to predict first seasonal onset of anthracnose lesions by using 8 years of data collected at Auckland, New Zealand, and disease progress during the season by using 3 years of data collected at Frelighsburg, Canada. Overall, the model provided accurate predictions of infection occurrence, with 0.96 accuracy, 0.91 sensitivity, and 0.97 specificity. The model also showed good accuracy for predicting disease progress, with a concordance correlation coefficient between observed and predicted disease severities of 0.92, a root mean square error of 0.14, and a coefficient of residual mass of 0.06. Although the model failed to predict 10 of 110 real infection periods, these missed infections led to only mild disease symptoms. We therefore conclude that the model is reliable and can be used to reduce the costs of anthracnose management by improving the timing of fungicide applications
Critical success factors for the adoption of decision tools in IPM
Full text linkThe rational control of harmful organisms for plants (pests) forms the basis of the integrated pest management (IPM), and is fundamental for ensuring agricultural productivity while maintaining economic and environmental sustainability. The high level of complexity of the decision processes linked to IPM requires careful evaluations, both economic and environmental, considering benefits and costs associated with a management action. Plant protection models and other decision tools (DTs) have assumed a key role in supporting decision-making process in pest management. The advantages of using DTs in IPM are linked to their capacity to process and analyze complex information and to provide outputs supporting the decision-making process. Nowadays, several DTs have been developed, tackling dierent issues, and have been applied in dierent climatic conditions and agricultural contexts. However, their use in crop management is restricted to only certain areas and/or to a limited group of users. In this paper, we review the current state-of-the-art related to DTs for IPM, investigate the main modelling approaches used, and the dierent fields of application. We also identify key drivers influencing their adoption and provide a set of critical success factors to guide the development and facilitate the adoption of DTs in crop protection
La gestione delle resistenze
No full text• Il termine resistenza si riferisce a riduzioni stabili ed ereditabili della sensibilità di un patogeno nei confronti di un fungicida (o di un gruppo di fungicidi);
• Per resistenza monogenica si intende la mutazione di un singolo gene che conduce ad un elevato livello di resistenza nei confronti di un particolare principio attivo; si tratta di una resistenza qualitativa (single step resistance) che può facilmente portare a problemi di contenimento della malattia (esempio: analoghi delle strobilurine);
• Per resistenza poligenica si intende la presenza di mutazioni su alcuni geni che conduce, generalmente, ad un basso livello di resistenza; si tratta di una resistenza quantitativa (multistep resistance) ed è caratterizzata da una graduale perdita di attività del principio attivo nel corso degli anni (esempio: inibitori della biosintesi degli steroli);
• Le sostanze attive utilizzate nei confronti di E. necator, ad eccezione di zolfo e meptyldinocap, sono considerate a rischio di resistenza da medio ad elevato;
• Per conservare l’efficacia dei prodotti a rischio di resistenza è importante seguire le indicazioni riportate in etichetta e/o disponibili in rete (in particolare su: www.frac.info) quali: dosi, limitazioni nel numero di interventi, utilizzazione in miscela e/o alternanza con prodotti a diverso meccanismo di azione, specie se multisito
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
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