1,720,970 research outputs found
Tar Spot of Corn: A Diagnostic and Methods Guide
No full textTar spot of corn is an emerging plant disease in the continental United States and Canada caused by the fungal pathogen Phyllachora maydis Maubl. Tar spot has been known to occur in Mexico, the Caribbean, and Central and South America since the early to mid-1900s. In 2015, it was reported for the first time in the continental United States. Since that time, tar spot has spread across corn-producing areas in the United States with epidemics as recent as 2021 resulting in significant yield losses. Although tar spot has been known to affect corn for over a century in the Americas, the biology of the pathogen, etiology, and epidemiology of the disease are not well understood. Additionally, symptoms and signs of tar spot resemble other foliar diseases and abiotic disorders of corn, which may lead to misdiagnosis. In this paper, we provide a brief description of current knowledge about tar spot of corn, including pathogen taxonomy, host range, symptoms and signs, specimen storage, pathogenicity testing, diagnostic protocols, and geographic distribution. This information will be useful to diagnosticians, researchers, and other professionals working with this disease.Minnesota Invasive Terrestrial Plants and Pests Center through the Minnesota Environment and Natural Resources Trust FundSolórzano, José E.; Cruz, C. D.; Arenz, Brett E.; Malvick, Dean K.; Kleczewski, Nathan M.. (2023). Tar Spot of Corn: A Diagnostic and Methods Guide. Retrieved from the University Digital Conservancy, 10.1094/PHP-04-22-0033-DG
Characterization of oomycete species causing soybean diseases in Illinois and management applications
Full text linkPhytophthora root and stem rot (PRR) and seedling diseases caused by oomycetes, are two of the most important yield limitations for soybean production in the US Midwest. Several species of Phytophthora and Pythium cause PRR and seedlings diseases, respectively. PRR is managed using cultivars with single resistance genes (Rps genes) in combination with seed treatments. In addition to Rps genes, cultivars with quantitative resistance or partial resistance are available for PRR management. The objective of this thesis is to develop precision management techniques for soybean diseases caused by oomycetes. Field experiments were conducted to evaluate resistant lines combined with an ethaboxam and metalaxyl seed treatment for PRR management. Experiments were conducted in three Illinois locations in 2017. Experiments were repeated in 2018 in one location in Urbana and one location in Iowa. The seed treatment protected stands in all locations in both years, but significant yield increases were only observed in high disease pressure environments. Both resistant and susceptible cultivars benefited from the seed treatment. For the second objective, soil samples and symptomatic plants were collected from 40 counties in Illinois to characterize the population of oomycetes in the state. Pythium ultimum var. ultimum (42%) was the most abundant species, followed by Ph. sojae (7%) and Ph. sansomeana (4%). In addition, ten more Pythium species were identified. Virulence of all Phytophthora spp. isolates was evaluated by inoculating 12 soybean differentials with known Rps genes. Sixteen pathotypes were identified among the Ph. sojae isolates, and no pathotypes were identified for Ph. sansomeana. The aggressiveness and fungicide sensitivity of the isolates was also evaluated. Aggressiveness assays were performed in the greenhouse for Phytophtora spp. isolates, and a petri plate assay was used to assess the aggressiveness of Pythium isolates. Ph. sojae was more aggressive compared to Ph. sansomeana. Py. ultimun var. ultimum, Py. ultimun var. sporangium, Py. irregulare and Py. aphanidermatum were the most aggressive Pythium species to soybean. Both Phytophthora spp. were sensitive to metalaxyl, mefenoxam, azoxystrobin, and ethaboxam. There were Pythium isolates insensitive to azoxystrobin and ethaboxam.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2021-09-16 without embargo termsThe student, Daniel Cerritos Garcia, accepted the attached license on 2021-04-08 at 16:23.The student, Daniel Cerritos Garcia, submitted this Thesis for approval on 2021-04-08 at 16:34.This Thesis was approved for publication on 2021-04-13 at 14:35.DSpace SAF Submission Ingestion Package generated from Vireo submission #16258 on 2021-09-16 at 16:40:40Made available in DSpace on 2021-09-17T01:10:43Z (GMT). No. of bitstreams: 2
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Previous issue date: 2021-04-1
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
Responses of paper birch (Betula papyrifera) to fertilization and amendment with a commercial mycorrhizal inoculant in two contrasting soil types.
No full textThe poor soil structure and fertility characteristic of urban soils are known to decrease the growth and survival rates of urban trees. Trees planted in such soils are more prone to damage by drought, flooding, and other stresses. It is believed that amending urban soils with ectomycorrhizal fungi (EMF), i.e. fungi that form one of several mutualistic associations with tree roots, improves tree growth and survival and decreases the need for soil fertilization and management. We tested a commercial mycorrhizal inoculant in nutrient and structure deficient subsoil, with and without fertilization, for effects on physiological traits and drought tolerance of paper birch (Betula papyrifera). Results were contrasted to those from equivalent treatments imposed on trees growing in nutrient and structure rich field topsoil. Measurements of photosynthesis, growth rates, total phenolics, and EMF abundance and diversity were made. Data obtained from small experiments conducted under laboratory light banks showed that the mycorrhizal inoculant promoted growth of paper birch seedlings while improving EMF colonization rates. In contrast, a larger greenhouse study showed no effects of the mycorrhizal inoculant on growth, productivity, or drought tolerance of seedlings. Although ectomycorrhizae were present on greenhouse seedlings, fungi present in the mycorrhizal inoculant did not form them; rather, they apparently were formed with fungi naturally present in the soil. In conclusion, the preponderance of the data suggests that treatment of trees with commercial mycorrhizal inoculants may not be as beneficial to urban trees growing in poor soil conditions as improving soil composition and structure
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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