1,720,975 research outputs found
First Report of Colletotrichum nymphaeae on Olive in Italy
No full textOlive anthracnose is one of the most important diseases of olive worldwide (Moral et al. 2009). Among the Colletotrichum species associated to the disease, some in the complexes C. acutatum and C. gloeosporioides have been reported as the most frequent in Italy (Schena et al. 2014). During the 2017 season, severe losses were reported in several (18) olive orchards (approximately 30 ha) located in the districts of San Daniele, Friuli Venezia Giulia, one of the northernmost olive growing areas in Italy. Drupes from cultivars Leccino and Leccio del Corno, at fruit size about 10% of final size (July), showed no symptoms or small, dark-brown rot lesion in the flesh; sometimes, peduncle was chlorotic, then necrotic, causing an easy detachment of the fruitlets. Symptomatic and asymptomatic fruits fell to the ground, determining a premature fruit drop of 70 to 80% of the fruit. Fruit with or without symptoms were surface sterilized in 2% NaOCl for 5 min, followed by 30 s in 75% ethanol, and then rinsed with sterilized distilled water. Fruitlets were sectioned with a sterile razor, and slices (1 mm thick) were seeded on potato dextrose agar plates amended with streptomycin-sulfate (250 mg/liter). Plates were incubated at 25°C for 8 to 15 days. Developing colonies showed a white to pale olivaceous, gray, aerial mycelium and partly with salmon to orange acervuli. Conidia were hyaline, smooth-walled, aseptate, straight, cylindrical to cylindric-clavate with one end round and the other rounded to acute, measuring 12.1 ± 2 × 5.1 ± 1.9 μm (mean ± SD). Culture and conidial morphology were in concordance with published descriptions of C. acutatum sensu lato (Damm et al. 2012). To confirm the identity, the internal transcribed spacer (ITS), the 28S ribosomal RNA (LSU), and partial sequence of β-tubulin (TUB2) regions of representative isolates were amplified and sequenced. A BLAST search revealed that all the sequences showed 99 to 100% homology with the corresponding sequences of previously identified Colletotrichum nymphaeae (Pass.) isolates in GenBank, and only one base difference in the TUB2 sequence, compared with the type strain (JQ949848). Sequences were deposited in GenBank with accession numbers MG906799 (ITS), MG906796 (LSU), and MH010593 (TUB2). Pathogenicity of C. nymphaeae was investigated using a pure culture of the isolates C290 and C291. Fruit (cv. Leccino) at the veraison stage (100 per isolate), were surface disinfected by dipping in 3.5% NaOCl for 1 min, rinsed in sterile distilled water, and arranged in sterile humid chambers. Fruit were then inoculated by depositing a drop (10 μl) of a spore suspension (104 conidia/ml) on the equatorial surface, which was pierced with a sterilized needle. Fruit treated with sterile distilled water served as a control. After 10 days incubation at 25 ± 1°C, all the inoculated fruit showed typical anthracnose symptoms and lesions with cream to salmon pink acervuli, whereas the controls remained healthy. The species C. nymphaeae was reisolated from the rotted fruit. Pathogenicity tests were repeated twice with the same results. C. nymphaeae has been previously reported to cause severe anthracnose on olive in Portugal (Talhinhas et al. 2005) and on multiple hosts in diverse parts of the world (Baroncelli et al. 2017). C. acutatum sensu stricto and C. godetiae have been reported as dominant species of olive anthracnose in Italy (Mosca et al. 2014); however, to the best of our knowledge, this is the first report of C. nymphaeae causing olive anthracnose in Italy
First Report of Dactylonectria torresensis Causing Foot and Root Rot of Olive Trees
No full textDuring the 2014 to 2016 growing seasons, a severe decline of olive (Olea europaea L., 8 to 30 years old) was observed in several orchards (approximately 50 ha) located in Apulia (Southern Italy). Affected trees (20 to 40% per orchard) showed stunted growth, chlorotic leaves, and dieback of twigs and branches. Root collar and large roots showed black, sunken, necrotic lesions, usually associated with linear bark cracking, frequently extended up to 60 to 70 cm height on the trunk. The necrotic lesions girdled the trunk, causing the death of the plant. Samples of necrotic roots and bark were collected from symptomatic trees, surface disinfected by dipping for 3 min in a dilution of 650 ml/liter of a commercial bleach containing 5.5% sodium hypochlorite with added stabilizers, and then rinsed in sterile distilled water. Portions (5 × 5 mm) from the leading edge between healthy and diseased tissue were plated onto potato dextrose agar (PDA) and synthetic low-nutrient agar (SNA) amended with streptomycin sulfate (300 mg/liter). After 8 to 10 days of incubation at 21 ± 2°C, colonies with Cylindrocarpon-like asexual morphology were isolated from 94% of affected trees. The colonies were pale yellow-brown to light chestnut in color, turning dark yellow to orange-reddish-brown with age. Several colonies (18 out of 21) among those with Cylindrocarpon-like morphology showed cottony to felt-like mycelia on PDA, beige to chestnut in color, whereas the remaining three were white to beige. On SNA, two selected isolates of the prevalent morphology (N37IL and N39IL) produced straight or slightly curved conidia, cylindrical, 1 to 3 septate, measuring 34.7 to 39.6 × 5.2 to 7.4 μm. Culture and conidial morphology were in concordance with published descriptions of Dactylonectria torresensis (Lombard et al. 2014) (syn: Ilyonectria torresensis [Cabral et al. 2012]). To confirm the identity, the internal transcribed spacer (ITS) region, partial sequence of β-tubulin (TUB2), and actin (ACT) genes were amplified using the primers ITS5/4, T1/bt2b, and ACT-512F/ACT-986R, respectively (Glass et al. 1995; White et al. 1990). Polymerase chain reaction products were sequenced and deposited in GenBank with accession numbers KP411806 (ITS), KP411801 (TUB2), and KP411804 (ACT). A BLAST search revealed that all sequences showed 99 to 100% homology with the corresponding sequences of previously identified D. torresensis isolates. Pathogenicity of D. torresensis in olive was investigated using a pure culture of the isolate N37IL. The foot and the roots of 1-year-old olive trees, cultivars Leccino and Picholine (10 replications per cultivar arranged in a completely randomized design), were inoculated by dipping the roots and the crown in a spore suspension (5 × 106 conidia/ml) or in sterile, distilled water (control) for 2 min. After transplanting in 5-liter pots, plants were kept outdoors under a structure with roof and side walls 3.5 m high made of shading screen (5 × 7 sun shade mesh), at a temperature approximately 18 to 28°C during the experiment. Five months after inoculation, most of the inoculated plants showed chlorotic leaves, like those observed in the field. Typical black-foot symptoms (Cabral et al. 2012) developed on all the inoculated plants within 7 months, whereas the controls remained healthy. D. torresensis with the same morphology as the initial isolate was reisolated from the inoculated plants. Dactylonectria spp. have been associated with black foot of grapevine worldwide (Carlucci et al. 2017) and D. macrodidyma caused root rot of olive in California (Úrbez-Torres et al. 2012). D. torresensis has the largest host range, including Vitis vinifera, and Abies, Quercus, Fragaria, and Viburnum spp. (Aiello et al. 2015; Lombard et al. 2014), and to our knowledge this is the first report of D. torresensis causing foot and root rot of olive trees worldwide
Integrated control of aerial fungal diseases of olive
No full textFoliar and fruit fungal diseases are responsible for severe yield losses in olives (Olea europaea L.) in most olive-growing areas around the world. Among the most important are leaf spot, anthracnose, cercosporiosis and drupe rot, respectively caused by Fusicladium oleagineum, Colletotrichum spp., Pseudocercospora cladosporioides and Botryosphaeria dothidea. Symptoms vary from tree defoliation, twig dieback, premature fruit fall and drupe rot, which can completely destroy olive production and reduce olive oil quality. Copper-based products and a few other compounds represent almost the only fungicides used to date to control aerial fungal diseases of olive. Moreover, although still permitted, the European authorities would like to see a ban on copper fungicides in conventional and organic farming across Europe, which would have a major impact on disease management in olive production. Under Directive 2009/128, the Sustainable Use Directive, National Action Plans for reductions in pesticide use, and the implementation of Integrated Pest Management on all farms in member states were reviewed by the European Union at the end of 2014 and became mandatory throughout member states. Extensive field trials conducted in southern Italy in recent years demonstrate that aerial fungal diseases of olive can be effectively controlled in an integrated management approach, using appropriately timed application of traditional fungicides and organically approved plant protection compounds, such as sulphur. Particularly, a new sulphur-based product, Thiopron®, was as effective as traditional fungicides in controlling both olive cercosporiosis and drupe rot caused by different fungal species
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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