1,721,104 research outputs found
Atti Giornate Fitopatologiche 2016 - Protezione delle piante, qualità, ambiente
No full textSi tratta di due volumi sia stampati che distribuiti in forma elettronica relativi al Congresso nazionale 2016 Giornate Fitopatologiche (cadenza biennale) - I due curatori seguono l'intera produzione dei contributi riportati: dall'invio delle bozze da parte degli autori fino alla stesura definitiva organizzando l'intero processo di correzione, verifica e invio alla stampa coadiuvati da un comitato scientifico
First Report of Resistance to Cyflufenamid in Podosphaera xanthii, Causal Agent of Powdery Mildew, from Melon and Zucchini Fields in Italy
No full textThe fungicide cyflufenamid (phenyl-acetamide, Fungicide Resistance Action Committee [FRAC] code U6) was approved for use in Italy in 2011 as Takumi (Certis Europe, Utrecht, The Netherlands) to control Podosphaera xanthii (Castagne) U. Braun. & N. Shishkoff, the main causal agent of cucurbit powdery mildew. Considering that strains of this pathogen have developed resistance to strobilurin (5) and demethylation inhibitor (DMI) (4) fungicides, cyflufenamid represented a viable alternative to control this disease. However, this fungicide is also prone to resistance development as illustrated by resistance of P. xanthii in Japan (3). In the 2012 and 2013 growing seasons, significant declines in cyflufenamid efficacy were observed in two experimental fields in the Apulia (AP) and Emilia-Romagna (ER) regions of Italy on Cucumis melo and Cucurbita pepo, respectively. Takumi had been applied four times at the recommended field rate of 0.15 liter/ha (15 μg/ml of active ingredient [a.i.]) each growing season since 2010 in each field. Powdery mildew-infected leaf samples were collected in 2012 from both fields (25 isolates from AP and 19 from ER), and from five gardens (one isolate per garden); while in 2013, samples were collected only from the ER field (two polyconidial isolates). Isolates were maintained on detached zucchini cotyledons (1). Sensitivity of the isolates to cyflufenamid was determined by leaf disk bioassays (4) using Takumi at 0.01, 0.1, 1, 10, 20, and 50 μg a.i./ml. The 50% effective concentration (EC50) and the minimum inhibitory concentration (MIC) values were calculated (2). Isolates collected in ER and the gardens in 2012 all had an EC5050 μg/ml, and MIC values from 50 μg/ml; by 2013, the EC50 values of ER isolates ranged from 3.35 to >50 μg/ml. Based on the mean EC50 value of 0.0019 μg/ml for sensitive isolates of P. xanthii in Japan (2), isolates from both the ER field and gardens in 2012 were considered sensitive to cyflufenamid. Additionally, EC50 values of AP isolates from 2012 and ER isolates from 2013 were greater than those of sensitive isolates, indicating a shift in sensitivity toward resistance to cyflufenamid (resistance factor >100 [2]). Consequently, poor control of powdery mildew with cyflufenamid applications in the AP and ER trials was most likely a result of fungicide resistance. Isolates from these fields were exposed to selection pressure for fungicide resistance because cyflufenamid was applied more times than permitted in the label instructions. However, control of powdery mildew in 2013 was not as effective as in previous years in commercial fields in AP (C. Dongiovanni, personal communication). This observation, combined with proof of reduced sensitivity of some P. xanthii strains in Italy to cyflufenamid, highlights the need for implementing resistance management strategies to minimize the risk of fungicide resistant strains developing in cucurbit fields.
References: (1) B. Álvarez and J. A. Torés. Bol. San. Veg. Plagas 23:283, 1997. (2) M. Haramoto et al. J. Pest. Sci. 31:397, 2006. (3) H. Hosokawa et al. Jpn. J. Phytopathol. 72:260, 2006. (4) M. T. McGrath et al. Plant Dis. 80:697, 1996. (5) M. T. McGrath and N. Shishkoff. Plant. Dis. 87:1007, 2003
Greenhouse assays on the control of the bacterial canker of kiwifruit (Pseudomonas syringae pv. actinidiae)
No full textBACKGROUND: Pseudomonas syringae pv. actinidiae (Psa) is the etiologic agent of the bacterial canker of kiwifruit, the most severe disease of Actinidia spp. This pathogen was firstly recorded in Japan and in China. The initial occurrence in Italy dates back to 1992, but the most important outbreak was in 2008. From that year, Psa has spread worldwide with a devastating virulence causing substantial losses to kiwifruit production in China, Italy, New Zealand, Chile, France and Portugal. OBJECTIVE: Screening the existing compounds with different mode of action for their efficacy in controlling Psa on Actinidia deliciosa (cv. Hayward) grown in controlled conditions. METHODS: Products were grouped according to their active ingredients and mode of action in the following categories: Copper compounds, plant extracts, disinfectants, resistance inducers, filming agents and biological control agents (BCAs). The experiments were performed on potted A. deliciosa (cv Hayward) vines grown in controlled greenhouse conditions. Inoculation was experimentally performed by spraying each plant till run off with a suspension of a highly virulent, biovar 3 Psa strain. Disease control and phytotoxicity were monitored for 15 and 30 days after inoculation. RESULTS: Copper compounds and resistance inducers (acibenzolar-S-methyl, Fosetyl-Al) showed the most promising results. However, few other compounds, such as some plant extracts and disinfectants (Verdeviva), provided some protection. Also biological control agents (BCAs), containing living microorganisms, partially controlled the disease. CONCLUSION: Copper compounds and resistance inducers can be possibly combined to develop a more robust and effective control strategy in open field. In addition, BCAs seem interesting, particularly in specific phenological stages when other control methods cannot be used, although results require further validation
First Report of Resistance of Peronospora belbahrii, Causal Agent of Downy Mildew of Basil, to Mefenoxam in Italy
No full textSweet basil (Ocimum basilicum L.) is an economically important herb crop in Italy, cultivated both in the greenhouse and field (about 1,000 ha) for fresh and mainly processed (pesto sauce) consumption. Downy mildew (Peronospora belbahrii) (Thines et al. 2009) was first reported in Italy in 2003 (Garibaldi et al. 2004). Currently, downy mildew is the major threat for covered and open field sweet basil, requiring several and continuous fungicide applications. Mefenoxam (metalaxyl-M) plus copper has been the most widely used and effective product against P. belbahrii, since its registration on basil in Italy in 2004. Recently, downy mildew control became problematic, most likely due to the efficacy reduction of mefenoxam. From 2012 to 2014, in the growing periods from June to September, 13 P. belbahrii samples (five in 2012, two in 2013, and six in 2014) were collected from three of the most important basil production areas of Italy (about 800 ha): Emilia-Romagna (nine samples), Liguria (three samples), and Veneto (one sample) regions, where disease control failures by mefenoxam-based programs were widely reported since 2012. Each sample consisted of 10 to 20 plants (O. basilicum type “Genovese”) with sporulating leaves. Field isolates were maintained on living plants of the same type in a greenhouse. Potted plants (O. basilicum type “Genovese”) at the stage of 8 to 10 leaves were sprayed with mefenoxam (Ridomil Gold SL, 43.88% [465 g/liter], Syngenta Crop Protection SpA, Milano, Italy) at a field rate of 22.8 g/100 liters. Mandipropamid (Pergado SC, 23.4% [250 g/liter], Syngenta Crop Protection SpA) at 50 ml/100 liters, and azoxystrobin (Ortiva, 23.2% [250 g/liter], Syngenta Crop Protecion SpA) at 100 ml/100 liters, both registered for use on basil in Italy, were sprayed as standard references, while untreated plants were kept as negative controls. Four plants per product and four untreated plants were used per field isolate. Twenty-four hours after treatment, each plant was spray-inoculated with a sporangia suspension of 5 ml/plant (105 sporangia/ml) of each collected field isolates. Plants were stored in plastic boxes overnight at 24 ± 1°C and 100% relative humidity (RH), in order to enhance disease infection. Hereafter, plants were kept in a greenhouse at 24 ± 1°C and 50 to 60% RH. At the appearance of symptoms on the untreated control (i.e., about 10 to 12 days after inoculation), the plants were placed overnight in plastic boxes at 100% RH. Disease severity was visually assessed by estimating the percentage of sporulated leaf area, according to Mersha et al. (2012). All assays were repeated at least twice. Among the 13 tested field isolates, 11 were resistant to mefenoxam (with an average sporulated leaf surface varying from 20 to 60%). Only two field isolates (collected in 2012 and 2014, both from two different areas in Emilia-Romagna) proved sensitive to mefenoxam while all isolates were sensitive to mandipropamid and azoxystrobin. Similar to a report from Israel (Cohen et al. 2013), our results confirm that poor control of P. belbahrii in areas of Italy with intensive use of mefenoxam (2 to 3 per cycle of production) is due to resistance development
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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