390 research outputs found
Fire blight (pear blight) of pears, apples, quinces, etc
No full textTitle from PDF caption (viewed on December 7, 2017).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Integrated disease management using environmental control in tea fields
No full textThe occurrence of plant disease depends on interactions between the host plant, a pathogen, and the environment in a dynamic called "the disease triangle". Bacterial shoot blight (BSB) disease, caused by _Pseudomonas syringae_ pv. _theae_ (_Pst_), is a major bacterial disease of tea plants in Japan and substantially reduces tea productivity. BSB mainly occurs in the low-temperature season, and lesion formation by _Pst_ is enhanced by both low temperature and the presence of ice nucleation-active _Xanthomonas campestris_ (INAX), which catalyses ice formation at -2 to -4^o^C and is frequently co-isolated with _Pst_ from tea plants^5^. Low temperature is thus the most important environmental factor to influence the incident; however, the effects of environmental controls in fields on the occurrence of the disease are poorly understood. Here we show that the natural incidence of BSB in the field is closely related to low temperatures in late autumn. Frost protection in late autumn, which protected tea plants against extremely low temperatures, significantly decreased the incidence of BSB, and frost protection combined with bactericide application held the incident under the economic threshold level. Our data indicate that environmental control in the field based on microbial interactions in the host offers a new strategy for plant disease control using integrated plant disease management based on the disease triangle concept
Bansal, Julia Singer. Municipal authority to address blight (2017) Municipal authority to address blight; Pinho, Rute. Municipal authority to address blight (2017). Municipal authority to address blight
No full text1 online resource (9 pages)Updated; "November 17, 2020."Discusses state laws authorizing municipalities to regulate and address blight. Updates OLR research report 2017-R-005
Bacterial blight of filbert
No full textTitle from PDF caption (viewed on December 8, 2017).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Control of walnut blight in Oregon
No full textTitle from PDF cover (viewed on December 14, 2017).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
An Evening with David Blight
No full textMonday evening, November 18, students from Gettysburg College got to sit down and discuss memory with Dr. David Blight from Yale University, author of the renowned work Race and Reunion. The session was conducted as an informal panel with Dr. Blight and Gettysburg College’s own Dr. Isherwood and Dr. Jordan. Dr. Blight spoke about beginning his work when memory studies was not an official field and stumbling his way headlong into working with the memory of the American Civil War. When discussing whether or not memory studies were a fad that would pass away, Blight reassured the audience that people have doing memory studies long before there was an official field. Memory is essential to who we are as human beings and all peoples and all nations construct their past in a way that is useable to their future. [excerpt
Identification and characterization of type III secretion inhibitors in Erwinia amylovora, the causal agent of fire blight of apple and pear
No full textFire blight is a destructive bacterial disease of apples and pears as well as other rosaceous plants and causes millions of dollar losses around the world each year. Erwinia amylovora is the causative agent of fire blight. The type III secretion system (T3SS) and exopolysaccharide (EPS) amylovoran are two major yet separate virulence factors in E. amylovora. Current fire blight management mainly relies on application of copper compounds and antibiotics. However, development of streptomycin resistant E. amylovora isolates in the US and other countries has made it ineffective. It is reasonable to believe that disabling the T3SS function may provide another way of controlling bacterial diseases. High-throughput screening of chemical libraries have identified small molecule inhibitors that attenuate T3SS of mammalian pathogens, but no study has been reported so far for plant pathogenic bacteria. In this study, three small molecules were identified to delay hypersensitive response (HR) development in tobacco. Using GFP as a reporter, six chemicals were identified to suppress T3SS gene expression of E. amylovora under hrp inducing conditions. Five of them belong to salicylidene acylhydrazides. Among them, chemical # 3 and # 9 were most potent in inhibiting T3SS gene expression in a dose-dependent manner without affecting bacterial growth. Furthermore, this group of chemicals also inhibited exopolysaccharide amylovoran production. Our results further demonstrated that chemical # 3 treatment resulted in growth reduction and symptom suppression on crab apple blossom. To better understand the mode of action of this class of compounds, we carried out a microarray analysis of E. amylovora treated with chemicals # 3 and # 9. A total of 534 and 183 genes were identified to be significantly differentially regulated by chemicals # 3 and # 9 treatment, respectively. The majority of genes in E. amylovora T3SS cluster including hrpL as well as effectors including avrRpt2 and hopC1 were down-regulated more than two folds by both chemicals # 3 and # 9. Chemical # 3 also suppressed the transcription of all amylovoran biosynthesis genes. Interestingly, the most significant upregulated genes were those involving iron acquisition and utilization. In addition, other compounds of this group (chemicals # 1, # 2, # 4) also exhibited a similar effect on gene expression, i. e suppressing T3SS and ams gene expression, while promoting iron uptake gene expression. Our results suggested that a common inhibition mechanism may be shared by these compounds. To test whether salicylidene acylhydrazides affect secretion of T3SS proteins, total secreted proteins from wild type bacteria grown in the presence or absence of chemicals # 3 or # 9 were quantified. Our results showed that chemical # 9 exhibited a dose-dependent inhibition of protein secretion in E. amylovora; while chemical # 3 was more effective, causing a complete blockage of secretion of T3SS proteins at as low as 5 μmol.Item withdrawn by Mark Zulauf ([email protected]) on 2012-07-11T14:10:50Z
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University of Illinois Theses & Dissertations (ID: 1)
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Refinements of Selberg's sieve
No full textThis thesis focuses on refinements of Selberg's sieve as well as new applications of the sieve. Sieve methods are addressed in four ways. First, we look at lower bound sieves. We will construct new lower bound sieves that give us non-trivial lower bounds for our sums. The lower bound sieves we construct will give better results than those previously known. Second, we create an upper bound sieve and use it to bound the number of primes to improve Selberg's version of the Brun-Titchmarsh Theorem. We improve a constant in the bound of the number of primes in an arbitrary interval of fixed length. Third, we construct an upper bound sieve to improve the large sieve inequality in special cases. Sieve methods allow us to improve this well-known bound of exponential sums. Finally, we include some notes on the use of successive approximations to give a choice of an upper bound sieve that minimizes the main term and the remainder term simultaneously.Ph.D.Includes abstractVitaIncludes bibliographical referencesby Sara Elizabeth Bligh
Investigations into the Characteristics of Historic Barley Varieties with Reference to Fungal Diseases and Physiology
No full textThe aim of this study was to characterise modern and historic barley varieties for agronomic and growth characteristics and to assess their resistance to Fusarium and mildew diseases.
Barley is a major agricultural crop cultivated throughout the world providing an important source of energy and protein for humans and animals. To achieve its potential, however, it must be carefully managed to avoid diseases particularly those caused by fungi which can cause serious economic losses and affect food safety and quality.
Contemporary barley varieties have been selected for yield and disease resistance. However, long term resistance to disease is increasingly difficult to achieve as microorganisms mutate and maintain their virulence. Investigating the potential of historic barley varieties as a genetic resource for future developments is one approach to obtaining novel attributes which may have been overlooked when breeding focused on yield rather than character of barley and on disease resistance.
To examine the characteristics and disease resistance of historic barley varieties a series of investigations was conducted. Initially a screening was initiated by growing thirteen historic barley varieties and two modern barley varieties in a field trial in 2009. Growth features, yield and symptoms of mildew and Fusarium Head Blight (FHB) were scored and compared. This field experiment was repeated in 2010 with six of these varieties at the John Innes Centre by deliberately exposing the plants to F. culmorum Fu 42. A further experiment was conducted at the same time by growing seven varieties in glasshouse conditions at the University of Sunderland under inoculated and uninoculated conditions.
From both growing seasons clear differences were found for the level of F. culmorum infection between the different barley cultivars with infection levels in heads ranging from 16% for Chevalier and 86.4% for Tipple barley varieties respectively. Nitrogen increased the level of FHB in all varieties possibly because
ii
of increased plant leaf number, tillers and humidity within the environment around the plant.
Mycotoxin analysis showed that F. culmorum infection resulted in mycotoxin contamination of all varieties. However, levels of mycotoxin were significantly lower in Chevalier barley compared to other barley varieties including the two modern varieties, Tipple and Westminster. Observations using scanning electron microscopy indicated a different pattern of fungal growth in Chevalier barley with limited fungal development on both external and internal surfaces compared to other susceptible varieties.
In general resistance against FHB disease depends on variable responses including plant physiology and morphology, antifungal compounds or resistance genes. Different flowering dates or flowering periods could be also considered reasons for different infection levels. However, in this study the duration of anthesis was not assessed and could be an important factor. Further experiments to identify the flowering times of different varieties could be considered for further research.
The lower levels of disease associated with lower levels of mycotoxins and a reduced fungal development in Chevalier barley indicated that this variety has a strong resistance against FHB disease. This may be because of its late flowering and its tall height minimising colonisation from the soil. However, Chevalier barley was found to be very susceptible to powdery mildew disease, particularly in glasshouse studies.
The potential of Chevalier barley to produce good malt was indicated when compared to modern varieties suggesting that Chevalier may be a valuable breeding stock for future developments
The control of walnut blight in the Pacific Northwest
No full textTitle from PDF cover (viewed on December 8, 2017).This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
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