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1
Orme, James. "Genetic dissection of barley powdery mildew resistance." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327590.
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2
Matheron, M. E., and J. C. Matejka. "Powdery Mildew of Cantaloupe - Testing New Fungicides for Disease Control." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/214478.
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Powdery mildew of cantaloupe, caused by the fungus Sphaerotheca fuliinea, is a perennial and often serious disease in Arizona. In 1989, potential new fungicides were evaluated for disease control in a field trial. All tested materials provided significant control when compared to untreated plants. Of the compounds tested only Bayleton currently is registered for use on cantaloupe. Rally, which performed extremely well in this test; should be available for use on cantaloupe in the near future.
3
Godwin, Jeremy R. "Resistance to powdery mildew disease in hops (Humulus lupulus L.)." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/63593.
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The virulence of eight isolates of Sphaerotheca humuli (DC.) Burr, was examined on nine varieties of hops (Humulus lupulus L.). Genotypes determined for varieties with race specific resistance generally agreed with previous reports. Although major genes for resistance usually conferred immunity from infection the effectiveness of the gene was shown to be reduced at low temperatures, thereby allowing weak sporulation to develop. The leaf blistering response previously considered to be a consequence of Rg gene determined resistance was shown to be unrelated to the expression of this gene. Quantitative microscopical examination of isolate/variety combinations exhibiting race specific resistance revealed that incompatible fungal sporelings were restricted in the early stages of their development. The expression of the Rg, and R^ resistance genes was associated with a reduction in the frequency with which germinated spores formed haustorial initials. Histochemical and ultrastructural studies showed that the hypersensitive reaction(cell death seen as granulation) in response to epidermal cell penetration was a feature common to most interactions involving major genes for resistance. Adjacent palisade mesophyll cells 'frequently also showed signs of reaction which in severe cases resulted in cellular browning. A 1,3—glucan (probably callose) was deposited in the paramural space and lignin-like compounds appeared to accumulate in the walls and cytoplasmic contents of most reacting mesophyll cells. Callose deposition and lignification were also observed in responding epidermal cells. Infection development on partially resistant breeding lines was studied under laboratory, glasshouse and field conditions. Laboratory experiments revealed that partial resistance to S. humuli was expressed as a reduction in the number of fungal colonies established, an increase in the incubation period and reductions in both the extent and intensity of sporulation. Cellular necrosis was less obvious than in race specific resistance. Comparative studies showed that plants severely infected as seedlings in a glasshouse screen were also severely infected when adult in the hop garden. However, in overall terms there was a relatively poor correlation between the levels of sporulation on seedlings and adult plants of partially resistant breeding lines.
4
Costadone, Laura. "Development and evaluation of detection-based air sampling programs for grapevine powdery mildew." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/l_costadone_041509.pdf.
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Thesis (M.S. in plant pathology)--Washington State University, May 2009.Title from PDF title page (viewed on May 26, 2009). "Department of Plant Pathology." Includes bibliographical references (p. 35-38).
5
Matheson, Michael E., and Joseph C. Matejka. "Powdery Mildew of Cantaloupe -- Evaluation of New Fungicides for Disease Control." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/214264.
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Powdery mildew of cantaloupe, caused by Sphaerotheca fuliginea, is a perennial and often devastating disease in Arizona. During 1987 and 1984 potential new fungicides were evaluated in field trials for disease control. In 1987, Bayleton, Rally and Spotless provided significant disease control. In 1984, Rally and Spotless significantly reduced development of powdery mildew, while Bayleton and Tilt were less effective. Uneven development of powdery mildew within the plot may partially explain the apparent lack of significant disease control in 1988 by Bayleton and Tilt.
6
Hague, Rachel Elise. "Genetics of quantitative resistance to powdery mildew in Fenman winter wheat." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267461.
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7
Pryce-Jones, Emily. "Erysiphe graminis f. sp. hordei and the role of extracellular cellulases in pathogenicity." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389410.
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8
Chung, Young-Soo. "Inheritance of powdery mildew resistance genes in 10 winter wheat lines." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/38655.
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9
Jin, Xiaolei. "Epidemiology and control of powdery mildew (Podosphaera aphanis) on strawberry." Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17212.
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Strawberry powdery mildew, caused by Podosphaera aphanis, has the potential to cause over 20% yield loss, particularly where strawberries are grown under cover. A holistic approach to the control of strawberry powdery mildew (P. aphanis) is important, since the disease is never absent from the crop. The new disease assessment key was developed to assess strawberry powdery mildew (the old one is for assessing red blotches on leaves, See appendix 8). The results (Chapter 3) showed that the disease is present in the crop when new plants are bought in from a propagator, with 14% of strawberry crowns were infected by P. aphanis in July 2013 and 4% of the strawberry plants had symptoms of powdery mildew in pre-assessment of plants for the 2013 Si nutrient fertigation field experiment. Control measures used in one growing season reduced the disease carry-over, thus reducing the initial inoculum in the following season. The use of a late autumn fungicide spray and a fungicide spray before the plants were covered by fleece in spring reduced the number and maturity of overwintering chasmothecia, thus contributing to a reduction in initial inoculum. The use of silicon (Si) nutrient (foliar spray and root treatment) also suppressed strawberry powdery mildew development (Chapter 4). The results of Area Under Disease Progress Curve (AUDPC) and the rate of epidemic growth curve (r) in 2012 indicated that the high concentration of Si nutrient foliar spray inhibited (r = 0.002, AUDPC = 44) the epidemic build-up of P. aphanis better than the low concentration of Si nutrient (r = 0.012, AUDPC = 51) and untreated (r = 0.018, AUDPC = 70). The Si nutrient root treatment (AUDPC = 12.8) was better in inhibiting strawberry powdery mildew development than the Si nutrient foliar spray treatment. Moreover, the high concentration of Si nutrient foliar spray resulted in fewer chasmothecia compared to the untreated. Si nutrient foliar spray and root treatments increased the concentration of Si in the plants and produced physiological changes in the plants, including wax formation on the adaxial leaf surface, greater leaf thickness and cuticle layer and increased Brix0 value in plants, which all were associated with reduced disease incidence. The integrated use of all these control strategies suppresses disease development so that control is achieved with less use of conventional fungicides.
10
Shen, Qian-Hua. "Functional analysis of barley MLA-triggered disease resistance to the powdery mildew pathogen." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972530398.
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11
Hossain, Mohammad Abul. "Powdery mildew on barley : pathogen variability in South Australia : resistance genes in cv. Galleon /." Title page, contents and abstract only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phh8287.pdf.
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12
Dagdas, Gulay. "Functional Analysis Of A Mirna Putatively Involved In Powdery Mildew Disease Susceptibility In Barley." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610642/index.pdf.
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Barley is one of the most important crop species in Turkey and powdery mildew is one of the most common pathogen decreasing yield in barley. For this problem, agricultural biologists apply breeding technologies in order to select and propagate resistant barley cultivars. However, this is not a permanent solution since pathogens evolve rapidly to overcome plant resistance mechanisms. On the other hand, molecular plant pathologists are trying to understand basic mechanisms underlying plant-pathogen interactions by using molecular tools in order to develop long term solutions for preventing yield loss. In this thesis, miR159 mediated regulation of barley GAMyb transcription factor is studied. According to microRNA microarray results regarding to infection with powdery mildew pathogen Blumeria graminis f.spp hordei (Bgh) at different time points, miR159 expression level showed significant differences. Bioinformatics analysis revealed that miRNA159 targets GAMyb gene in barley. In order to investigate this relationsh‟
p, both miRNA and miRNA target were cloned into GFP containing expression vectors through Gateway cloning and resulting vectors were transformed into Nicotiana benthamiana through Agrobacterium mediated gene transfer. Observations based on GFP expression showed that miRNA159 targets and decreases the expression of GAMyb in vivo. v To conclude, this study can be evaluated as a distinctive study for two aspects
(i) it is the first study assessing a &ldquo
putative&rdquo
barley miRNA function biologically and (ii) developed a practical and effective functional assay for miRNA studies in plants.
13
Farinas, Coralie. "Understanding the Powdery Mildew Disease of the Ornamental Plant Phlox: Combining Applied and Basic Research." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1594375153330343.
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14
Majule, Amos Enock. "The effects of organic residues and elemental sulphur additions to soils of southern Tanzania." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287642.
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15
Liu, Bo. "Sustainable strawberry production and management including control of strawberry powdery mildew." Thesis, University of Hertfordshire, 2017. http://hdl.handle.net/2299/19051.
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At present, the global population is increasing, while soil and fresh water resources for crop production are declining. It is important to adopt sustainable practices to optimise the use of limited natural resources without compromising the environment, and to enhance continuous production in the long term. The rapid growth of UK strawberry industry has been achieved through the precision use of varieties, nutrients and polythene tunnels. This intensive production has caused significant environmental impacts especially Greenhouse Gas (GHG) emissions from the production. Strawberry powdery mildew (Podosphaera aphanis) is a major fungal disease affecting strawberry production worldwide particularly in polythene tunnels. The disease can result in yield losses of up to 70% of the crop. A ruleQbased system was used in the field trials to predict high risk days of P. aphanis development, taking into account the optimal environmental conditions conducive to conidial germination and disease development. The results (Chapter 3) showed that the use of this prediction system achieved satisfactory control of P. aphanis in commercial strawberry production, with reduced fungicide applications compared with commercial spray programme. The results were consistent in two consecutive years and on different varieties. In addition, it was suggested that the use of the prediction system may also lead to lower GHG emissions associated with fewer fungicide applications, thereby benefit strawberry growers both environmentally and economically. Results from 2014 & 2015 silicon fertigation trials showed that the use of a silicon nutrient via the fertigation system reduced the strawberry susceptibility to P. aphanis and twoQspotted spider mites (Tetranychus urticae Koch) in two consecutive years on different varieties (Chapter 4). In both years, crops received the silicon nutrient only without fungicides had both lower rate of epidemic (r) and lower value of Area Under the Disease Progress Curve (AUDPC) (r = 0.0036, AUDPC = 475 in 2014; r = 0.001, AUDPC = 267 in 2015) compared with the untreated control (r = 0.0042, AUDPC = 662 in 2014; r = 0.0011, AUDPC = 281 in 2015). Silicon also delayed the epidemic buildQup in the silicon nutrient only treatment for approximately two weeks compared with the untreated control. Crops from the silicon nutrient plus fungicides treatment had lower susceptibility (r = 0.0012 in 2014; r = 0.0004 in 2015) than those from the fungicides only treatment (r = 0.0017 in 2014; r = 0.0005 in 2015) suggesting that the silicon nutrient may also enhance fungicides performance in reducing the epidemic buildQup when used together. Moreover, the presence of T. urticae on strawberry leaves was significantly lower (P < 0.001) in plants treated with the silicon nutrient than those without. In addition, initial results suggested that silicon may play a positive role in raising °Brix of strawberry leaf petiole, improving pollen viability, and influencing the length of flower receptacle and stamens. Maltmas Farm has a wide range of semiQnatural habitats that provide food and nesting resources for wild pollinators. Hoverflies, bumblebees and solitary bees were found to be the main wild pollinators that pollinate commercial strawberries at Maltmas Farm (Chapter 5). The number of pollinators in tunnels or open fields significantly correlated with the abundance of strawberry flowers (P < 0.05). Pollinator presence also differed between groups throughout the day and over the seasons. Hoverflies appeared early in the day and were abundant in summer months; bumblebees and solitary bees were present most of the day and throughout the season, whereas honeybees were only active in sunny days. Temperatures, relative humidity and cloud coverage also affected pollinator presence. In addition, pollinator activity was not significantly (P > 0.05) affected by the application of the silicon nutrient via the fertigation system. The integrated use of the prediction system (to reduce fungicide applications and subsequent GHG emissions), the silicon nutrient (to reduce crop susceptibility to P. aphanis and T. urticae), and sustainable farmland management (to encourage the presence of wild pollinators) could help strawberry growers to achieve a more sustainable production.
16
Voutsadaki, Panagiota. "The contribution of salicyclic acid and camalexin to RPW8-mediated disease resistance to powdery mildew in arabidopsis." Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445509.
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17
Tan, Wan-Zhong. "Relationships between foliar disease and loss of grain yield in barley with particular reference to powdery mildew." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283592.
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18
Jaggard, Daniel Andrew William. "The structure and function of RPW8.1 and RPW8.2, powdery mildew disease resistance proteins from Arabidopsis thaliana (L.) Heyhn." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251898.
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19
Fatema, Kaneez. "The effect of silicon on strawberry plants and its role in reducing infection by Podosphaera aphanis." Thesis, University of Hertfordshire, 2014. http://hdl.handle.net/2299/14445.
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Podosphaera aphanis which causes powdery mildew of strawberry is of economic importance in strawberry production in United Kingdom as it affects yield and fruit quality. Silicon has been shown to reduce the severity of a number of plant diseases. In strawberry, the mechanism of suppression against powdery mildew remains uncertain. Therefore, it has been suggested that supplying silicon would help strawberry plants to absorb silicon and improve resistance against the pathogen. The silicon based wetter Omex SW7 was used and three different concentrations of silicon wetter were applied on the leaves of the strawberry plants (foliar application). Each treatment was applied at three different timings. Enhanced level of silicon was quantified by the Autoclave Induced Digestion (AID) method. Whilst the main study has used the variety Elsanta, other varieties have also been used. It was observed that the weekly application (total 5 sprays) of 3 different concentrations of Omex SW7 on leaves showed significantly (P<0.05) higher silicon concentrations compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. Microscopic observations showed that weekly application of standard, high and very high concentrations of Omex SW7 significantly (P<0.05) increased the number and length of leaf hairs on both the upper and lower surfaces of strawberry leaves. The different varieties of strawberry used showed morphological changes in the leaves with regard to the density and length of leaf hairs. Untreated leaves from Rhapsody had no hairs on the upper leaf surface, but a low density of hairs was observed after treatment with the high concentration of Omex SW7. In this study, Omex SW7, a silicon based wetter was applied to the roots of strawberry plants (root application) and silicon accumulation and physical changes in leaves were assessed. Strawberry variety Elsanta was used in this experiment. Results revealed that weekly application (total 5 applications) of 2 different concentrations (standard and high) of Omex SW7 to roots showed significantly (P<0.05) higher silicon concentrations compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. It was found that the weekly application of two different concentrations of Omex SW7 showed significantly higher (P<0.05) leaf hair numbers and significantly (P<0.05) longer leaf hair length on both the upper and lower surfaces of leaves compared to application 3 times in weeks 1, 3 and 5 or twice in weeks 1 and 5. The effect of foliar application of silicon and potassium carbonate to limit P. aphanis infection was examined in a field trial under polythene tunnel at Wisbech. Treatments were arranged in a randomised block design of 3 replicates. There were a total of 18 plots. There were six treatments and all treatments were applied to the strawberry variety Sonata. Results revealed that application of silicon based wetter Omex SW7 onto the leaf surface does result in accumulation of silicon in the leaves. The application of Omex SW7 has stimulated an increase in the number and length of leaf hairs in strawberry plants. Results showed that germinating ascospores and colonies were present in all plots before the trial was sprayed. Treatments with standard and high Omex SW7 significantly (P<0.05) reduced the number of germinating ascospores and colonies in this trial. However, Potassium carbonate alone gave some reduction in the number of colonies and germinating ascospores. Moreover, potassium carbonate mixed with silicon based wetter Omex SW7 significantly (P<0.05) reduced the number of germinating ascospores and colonies.
20
Stößel, Bastian Verfasser], Manfred [Akademischer Betreuer] [Frühauf, Bernd [Akademischer Betreuer] Freier, and Christel [Akademischer Betreuer] Richter. "Weather-disease relationships and future disease potential of leaf rust and powdery mildew in Saxony-Anhalt / Bastian Stößel. Betreuer: Manfred Frühauf ; Bernd Freier ; Christel Richter." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2015. http://d-nb.info/1081077646/34.
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21
Ali, Mohamed A. "Cell and tissue culture of tomato : application to disease resistance to powdery mildew (Erysiphe cichoracearum) and leaf spot (Xanthomonas campestris pv. vesicatoria)." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317304.
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22
Toufexi, Eleftheria. "Effect of hybrid choice and soil and foliar elicitor treatments on powdery mildew disease severity, crop performance and/or expression of disease resistance mechanisms in tomato and courgette plants." Thesis, University of Newcastle Upon Tyne, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601791.
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This aim of the study was to investigate the effect of using less susceptible hybrids, and sailor foliar applied elicitor treatments (Milsana, chitin/chitosan) on powdery mildew disease severity and crop performance parameters in greenhouse grown tomato and courgette. The second aim of the study was to investigate potential mode of actions of elicitors against powdery mildew. Two glasshouse experiments were performed with tomato plants under environmental conditions which resulted in the absence of powdery mildew infection; this allowed the effects of elicitor treatments on tomato plant growth and fruit yield and quality parameters to be determined in the absence of confounding effects of mildew infection. These data were then combined with data sets from identical trials carried out under contrasting environmental conditions and mildew disease pressure and used in multivariate analyses designed to identify associations between a environmental and agronomic drivers on tomato performance. Tomato yield and sugar content were only affectcd by hybrid choice, with the less susceptible tomato hybrid Elpida showing higher yield and higher sugar fruit content. Truss and leaf numbers were reduced by the use of Milsana and the sulphur fungicide treatment, which was included in the study as a positive control. Leaf chlorophyll was found to be higher in plants of the less susceptible hybrid Elpida and those treated with Milsana. Total antioxidant activity was not significantly affected by elicitors, but there was a trend towards higher antioxidant levels where standard Milsana treatment \vas applied. Multivariate analyses suggest that the environmental factors, relative humidity, mean and maximum daily temperature, were significant drivers. Powdery mildew severity was strongly positively associated with relative humidity and negatively with mean and maximum daily temperature. Leaf chlorophyll content was strongly negatively associated with relative humidity and positive ly with mean and maximum daily temperature. The drivers non-use of chitin soil amendment and foliar treatment (untreated control) were also identified as highly significant. Total fruit yield, number of fruits and fruit diameter were strongly positively associated with these drivers.
23
Dantec, Cécile. "Caractérisation des contraintes biotiques et abiotiques sur la phénologie printanière du chêne : expliquer les patrons de diversité et prédire les changements futurs." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0042/document.
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La phénologie du débourrement est un caractère majeur d’adaptation des arbres à leurenvironnement en milieu tempéré. Notre objectif a été de caractériser les contraintes biotiques (oïdium) etabiotiques (températures hivernales et printanières / gels tardifs) s’exerçant sur le débourrement afind’expliquer les patrons de variation phénologique intra et inter populationnelle observés chez le chêne(Quercus petraea) le long d’un gradient altitudinal. Nous avons utilisé une approche combinantobservations in situ, expérimentation, et modélisation. Nous avons mis en évidence que l’évitement desgels tardifs printaniers est un caractère adaptatif majeur le long du gradient altitudinal. La tardiveté dudébourrement pourrait être due à des besoins plus importants en température de forcing. Par ailleurs, lechampignon n’est pas adapté localement à la phénologie de son hôte et les individus et les populationssont alors inégalement exposés à la maladie. En montant en altitude, les chênes sont de plus en plusexposés au champignon, mais les facteurs environnementaux sont défavorables à une plus forte infection.A basse altitude, l’oïdium et les gels tardifs favorisent des phénotypes phénologiques opposés(respectivement précoces vs. tardifs) ; la combinaison des deux contraintes pourrait donc contribuer aumaintien de la forte diversité phénologique observée. D’autre part, nous avons observé que l’infection parl’oïdium engendre une augmentation du polycyclisme chez les semis de chêne au cours de la saison decroissance, ce qui les rend moins résistants aux gels hivernaux. Nous montrons qu’il est important que lesmodèles phénologiques à visée prédictive intègrent la phase de chilling aboutissant à la levée dedormance. Le manque de chilling ne semble pas encore un facteur limitant, mais la tendance actuelle à undébourrement de plus en plus précoce sera probablement freinée voire inversée au milieu du siècle enbasse altitude, dans la marge sud de distribution de Q. petraeaBudburst phenology is a major adaptive trait of trees to the environment in temperateclimate. Our aim was to characterize the biotic (powdery mildew) and abiotic (winter and springtemperatures / spring frost) constraints acting on budburst in view to explain the patterns of intra and interpopulations’ phenological variation observed in sessile oak (Quercus petraea) along an elevation gradient.We based our approach on in situ monitoring, experimentation and modeling. Our results highlight that theavoidance of late spring frosts is a major adaptive trait along the elevation gradient. The lateness inbudburst might be due to higher requirements in forcing temperatures. Otherwise, the fungus is not locallyadapted to its host phenology so oak individuals and populations are unequally exposed to the disease.With increasing elevation, oaks are more and more exposed to the fungus, but the environmental factorsare unfavorable to higher infection. At low elevation, powdery mildew and late spring frosts favor oppositephonological phenotypes (early-flushing vs. late-flushing trees, respectively); the combination of the twopressures may thus contribute to the maintenance of the observed high phenological diversity. We alsoshowed that powdery mildew infection induced an increased polycyclism during the growing season in oakseedlings, which made them less resistant to winter frosts. Predictive phenological models will have toinclude the chilling phase which conditions dormancy breaking. Although the lack of chilling is not yet alimiting factor, the current trend in increasingly advanced budburst will certainly be slowed or even reversedin the middle of the century at low elevation, in the southern margin of the distribution area of Q. petraea
24
Ozgazi, Nese. "Proteome Analysis Of Blumeria Graminis F. Sp. Hordei Inoculated Barley." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611152/index.pdf.
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Blumeria graminis f. sp. hordei is a biotroph pathogen that causes powdery mildew disease in barley. In this study, Pallas01 and Pallas03 barley lines having Mla1, Ml (Al2) and Mla6, Mla14 R-genes were inoculated with Bgh103(64/01) race of the Blumeria graminis f. sp. hordei having avirulence and virulence to Pallas01 and Pallas03, respectively.
The proteins were isolated from the three biological replicates of 12, 24, and 48 hpi samples following the method in Rampitsch et al., 2006. These there biological replicates of three time points together with the mock inoculated plant proteins were separated on 2D-PAGE using IPG strips of 4-7 pH values as three technical replicates, resulting 108 gels.
The gels were analyzed using PdQuest (Bio Rad) in order to assess up- or down-regulated protein spots by comparing against controls and the samples having resistance or susceptible responses with each other. According to the analysis, 36 proteins were found to be differentiated and among them 18 proteins were found up-regulated and 8 proteins were found down-regulated. The spots were manually
v
excised and subjected to the nano-LC-ESI-MS/MS analysis (Proteome Factory, Germany). The MASCOT algorithm was used for identification of the possible proteins. The experimental pI and MW values were used for selecting the differentiated proteins from the mass results.
The relative abundance of each of the 38 identified polypeptides was calculated in terms of spot intensity. The majority of the most abundant proteins were found to be carbohydrate metabolism related. The relative distribution of the proteins into four main functional categories was taken into consideration.
Statistical tests (Students‟
T-test) were carried among the identified proteins in order to reveal statistically significant proteins throughout the study. By making a WoLF PSORT search, subcellular localization of the proteins was predicted. Accordingly, most of the proteins were found to be located in cytoplasm or chloroplast.
25
Evans, Katherine J. "Characterization of Uncinula necator, the grapevine powdery mildew fungus." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phe924.pdf.
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Bibliography: leaves 148-166. This study identifies genetic variation in Australian Uncinula necator populations. Techniques were developed for molecular and phenotypic markers for U. necator. Mating types of Australian clonal lines were identified and viable cleistothecia and infective ascospores were produced in vitro. The study establishes the foundation for investigating the population biology of U. necator, by identifying two distinct genetic groups, A and B, and micro-geographical variation among 35 clonal lines from various Australian viticultural regions.
26
Priddey, Gemma D. "Signal transduction in the barley powdery mildew fungus." Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:7f189f07-ad91-4dea-9760-a41bda8c498c.
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Barley powdery mildew disease is caused by the highly specialised phytopathogenic fungus, Blumeria graminis f.sp. hordei. Disease is spread prolifically by the production of asexual conidia. Following contact with the barley leaf surface, a short, primary germ tube (PGT) emerges, followed by elaboration of a second-formed germ tube, the appressorial germ tube (AGT). This second-formed germ tube elongates, swells and hooks to form an appressorium, which allows direct penetration of the barley cuticle and infection of the host. Infection structure differentiation in B. graminis is a highly regulated and complex process. It demands the coordinated perception of multiple external signals, but little is known about how these signals are integrated and transduced within the fungus. Protein kinase A (PKA) and cAMP signalling are known to play important, but complex, roles during infection structure development. However, signalling via cAMP alone is not sufficient to promote progression through infection structure differentiation. This study describes the characterization of two B. graminis protein kinase C genes, pkc1 and pkc-like. PKC activity was identified in B. graminis protein extracts. Efforts to find an inhibitor specific for B. graminis PKC were unsuccessful. However, phorbol ester, a PKC agonist, invoked both appressorium formation when applied to spores in vivo and PKC activity in protein extracts. In addition, real-time PCR confirmed the differentially regulated transcript profiles of both pkc1 and pkc-like, revealing a peak in transcript levels just prior to PGT emergence for pkc1, and during PGT differentiation for the pkc-like gene. Two mitogen-activated protein (MAP) kinases, mpk1 and mpk2, were characterized. MAP kinase activity was detected in conidial protein extracts. The MAP kinase kinase (MEK) inhibitor, PD98059, inhibited B. graminis germling morphogenesis. However, a MAP kinase agonist failed to show any effect on germling differentiation. In addition, real-time PCR confirmed the differentially regulated transcript profiles of both mpk1 and mpk2, and revealed a peak in transcript levels during appressorial germ tube elongation and swelling for both genes. The "model" phytopathogenic fungus, Magnaporthe grisea, was employed as a "surrogate host" for the functional analysis of the B. graminis MAP kinase gene, mpk1. Firstly, the mpk1 promoter was sequenced and a plasmid construct made comprising the mpk1 gene under the control of the mpk1 promoter. This, and the control construct, that is the M. grisea PMK1 gene under the control of the PMK1 promoter, were transformed into M. grisea Δpmk1. Southern analysis identified transformants for phenotypic studies. These showed that whereas Δpmk1 was complemented by M. grisea PMK1 in the control experiments, B. graminis mpk1 failed to complement Δpmk1. Expression studies showed that there was no expression of mpk1 in an mpk1 transformant.
27
Kithul-Pelage, Renuka Nilmini Attanayake. "Species and population diversity of powdery mildews on grain legumes in the US Pacific Northwest." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/r_attanayake_kithul_pelage_070808.pdf.
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Thesis (M.S. in plant pathology)--Washington State University, August 2008.Title from PDF title page (viewed on Mar. 11, 2009). "Department of Plant Pathology." Includes bibliographical references.
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Senior, Ian James. "The mode of action and mechanisms of resistance to triazole fungicides in Erysiphe graminis." Thesis, University of Bristol, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281867.
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Olsen, M., S. Rasmussen, C. Nischwitz, and M. Kilby. "Effect of Powdery Mildew on Pecan Nut Weight and Quality." College of Agriculture, University of Arizona (Tucson, AZ), 2000. http://hdl.handle.net/10150/223843.
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Powdery mildew of pecan, caused by Microsphaera ulni, results in discoloration of pecan shucks, but its effects on yield and quality of kernels are not known. In 1999, powdery mildew was observed on pecan shucks by the latter part of June in a commercial pecan orchard near Sahuarita, Arizona. The fungus continued to be active throughout the summer. However, results of a field test comparing diseased and healthy nuts from two varieties of pecans indicate that powdery mildew did not affect nut weight or quality. Whole nut weights, kernel weights, color ratings or percentage of discarded nuts were not significant between paired clusters of nuts that were treated with fungicides and remained disease free and untreated nuts that were infected with powdery mildew. Although shucks may have a high percentage of area covered by powdery mildew, results from this trial indicate that fungicide treatments are not warranted.
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Hibberd, Julian. "Effects of elevated COâ†2 on biotrophic pathogens : powdery mildew of barley." Thesis, Bangor University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484121.
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Matheron, Michael E., and Martin Porchas. "Powdery Mildew of Cantaloupe: Comparison of Chemical Management Tools in 1996." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221637.
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Powdery mildew of cantaloupe and other melons occurs every year in Arizona; however, the incidence and severity of the disease is quite variable. This disease, caused by the plant pathogenic fungus Sphaerotheca fuliginea, is favored by moderate temperature and relative humidity, succulent plant growth and reduced light intensity. Potential new fungicides were evaluated for disease management in a field trial conducted in the spring of 1996. All tested products significantly reduced the level of disease compared to nontreated melon plants. In addition to compounds already registered for use on cantaloupe, such as Microthiol Special, Reach, Benlate, Bayleton and Bravo, the list of efficacious nonregistered agrochemicals included Quadris, Procure, BAS-490, and Rally. The possible availability of new disease management tools in the future for powdery mildew of cantaloupe and other melons could enhance our efforts to reduce the development of resistance to these fungicides by the pathogen.
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Matheron, M. E., and J. C. Matejka. "Potential New Fungicides for Control of Powdery Mildew of Cantaloupe - 1990 Evaluation." College of Agriculture, University of Arizona (Tucson, AZ), 1991. http://hdl.handle.net/10150/221440.
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Powdery mildew of cantaloupe, caused by the plant pathogenic fungus Sphaerotheca fuliginea, is usually found in some melon fields every year. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. In the spring of 1990, potential new fungicides were evaluated for disease control in a field trial All tested materials provided significant control when compared to untreated plants. Bayleton is the only tested material that is currently registered for use on cantaloupe for control of powdery mildew.
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Matheron, Michael E., and Martin Porchas. "Downy and Powdery Mildew of Lettuce: Comparison of Chemical Management Tools in 1997." College of Agriculture, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/221600.
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Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development of downy mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for management of these diseases in 1997. A very low level of downy mildew occurred during this trial; however, all treatments significantly reduced the number of leaf lesions compared to nontreated lettuce plants. Powdery mildew was quite intense at crop maturity and was significantly lower, compared to nontreated lettuce, on plants treated with Microthiol Special, BAS 490 + Bravo Weather Stik, Quadris, and two additional treatments not usually found to reduce this disease.
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Matheron, Michael E., and Martin Porchas. "Comparison of New Fungicides for Management of Powdery Mildew of Cantaloupe in 1997." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/221678.
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Powdery mildew of cucurbits, which include cantaloupe, honeydew and watermelon as well as cucumbers and squash, occurs every year in Arizona. Moderate temperatures and relative humidity, succulent plant growth and reduced light intensity are factors that favor the development of powdery mildew, which is caused by the pathogenic fungus Sphaerotheca fuliginea Potential new fungicides were evaluated and compared to existing chemicals for control of powdery mildew of cantaloupe in a field trial conducted in the spring of 1997 at the Yuma Agricultural Center. The top performer in this study for disease control as well as reduction in culled fruit was a combination of Topsin-M + Trilogy. Other effective materials included BAS 490, Quadris, Procure, Benlate, Microthiol Special and Rally. Bayleton significantly reduced the amount of culled fruit, but did not significantly reduce the severity of powdery mildew. Compared to nontreated plots, a gain of up to $973 per acre could have been realized due to the reduction in amount of culled fruit in plots treated with fungicides. The potential availability of new chemistries for management of powdery mildew of cantaloupe and other cucurbits could help in the implementation of fungicide resistance management strategies, which strive to minimize the risk of resistance development by the pathogen to these compounds.
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Matheron, M. E., and J. C. Matejka. "Fungicides Evaluated for Control of Powdery Mildew of Cantaloupe in 1991 Field Trial." College of Agriculture, University of Arizona (Tucson, AZ), 1992. http://hdl.handle.net/10150/214511.
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Leaf drop of lettuce, caused by the plant pathogenic fungi Sclerotinia sclerotiorum and S. minor. occurs every year in some lettuce fields in Arizona. When environmental conditions are favorable, disease incidence and resulting crop loss can be significant. During the 1990-1991 lettuce season in western Arizona, different fungicides and rates of materials were evaluated in the field for disease control. All tested materials increased yields compared to not using any fungicide for disease control.
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Matheron, Michael E., and Martin Porchas. "Management of Powdery Mildew on Cantaloupe: Efficacy of Fungicides in 1995 Field Trial." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/214736.
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Powdery mildew of cantaloupe and other melons in Arizona is caused by the plant pathogenic fungus Sphaerotheca fuliginea. The disease is found in melon fields each year; however, the incidence and severity of the disease is quite variable. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. Potential new fungicides were evaluated for disease management in a field trial conducted in the spring of 1995. In this study, BAS-490 and Reach provided the highest level of efficacy among the materials and rates tested. Generally, lower levels of disease led to increased yield of marketable fruit.
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Uaciquete, Americo. "Epidemiology and control of powdery mildew (Oidium anacardii Noack) on cashew (Anacardium occidentale L.) in Mozambique." Diss., University of Pretoria, 2003. http://hdl.handle.net/2263/24486.
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For a successful and economical integrated control program aimed at a particular disease, pertinent information, regarding the environmental conditions prevailing in the growing area, the crop itself and the pathogen, must be available. Recently, the control of powdery mildew disease on cashew has moved from the use of non-systemic fungicides with a wide range of action, to highly specific systemic ones. Such a shift requires a more effective integrated control system, whereby tolerant varieties in combination with fungicide unaffected biocontrol agents are timely used to ensure disease control and reduce the hazards associated with excessive fungicide applications. The purpose of this study was to understand the relationship between the disease epidemic and some climatic factors over time. Appropriate periods for management interventions were determined. The cellular host reaction to infection by Oidium anacardii Noack was studied with a view to rapidly identify disease tolerant host types. Potential antagonists were isolated, screened and compared with commercial biocontrol products using in vivo techniques and chemical control programs were finally evaluated. Electron microscopy elucidated that the powdery mildew tolerant cashew variety (H1) had a relatively higher consistency of cytoplasmic aggregates upon infection by O. anacardii when compared to the susceptible clone. Based on conidia and conidiophore morphology, conidial germination and conidiogenesis processes observed indicated that O. anacardii belongs to the subgenus Pseudoidium (Y.S. Paul&J.N. Kapoor) comb.Et. Stat. Nov. (Holomorph Erysiphe Sect. Erysiphe U. Braun). There was no direct relationship between the progress of the cashew powdery mildew epidemic and temperature, relative humidity or dew point over time. However, the epidemic did not start until conditions of average temperatures under the tree canopy were below 30°C, relative humidity was 80% and dew point was above 15. In vivo screening of 72 isolates, amongst them bacteria and fungi, from cashew leaves and florets showed that none were effective against O. anacardii, the causal agent of cashew powdery mildew. However, commercial antagonists, Candida saitoana, Bacillus subtilis and B. licheniformis, significantly reduced the growth and branching of primary hyphae. One antagonist, B. licheniformis, was as effective as the commercial fungicide triadimenol 25% EC (Bayfidan). Chemical fungicides were found to be effective against powdery mildew; however, the currently prevailing economic environment in Mozambique was found inappropriate for the use of expensive organic fungicides. Additional gain from the use of fungicides was found to be solely qualitative and thus did not represent a fair investment return ratio in terms of cashew nut prices and production costs. The use of integrated cashew management was finally recommended. Further studies should focus on development of integrated and cost effective disease management strategies.Dissertation (MSc(Plant Pathology))--University of Pretoria, 2003.
Microbiology and Plant Pathology
unrestricted
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Matheron, M. E., J. C. Matejka, and M. Porchas. "Field Testing of Potential New Fungicides for Control of Powdery Mildew of Cantaloupe, 1993." College of Agriculture, University of Arizona (Tucson, AZ), 1994. http://hdl.handle.net/10150/214730.
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Powdery mildew of cantaloupe in Arizona is caused by the plant pathogenic fungus Sphaerotheca fuliginea. The disease is usually found in some melon fields each year; however, the incidence and severity of the disease is quite variable. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. Potential new fungicides were evaluated for disease control in a field trial conducted in the spring of 1993. All tested materials provided significant control when compared to untreated cantaloupe plants. In this study, none of the compounds provided disease protection significantly superior to that demonstrated by Bayleton, the fungicide currently registered for use on cantaloupes.
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Matheron, Michael E., and Martin Porchas. "Field Evaluation of Potential New Fungicides for Control of Powdery Mildew of Cantaloupe in 1994." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/221471.
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Powdery mildew of cantaloupe in Arizona is caused by the plant pathogenic fungus Sphaerotheca fuliginea. The disease is found in melon fields each year; however, the incidence and severity of the disease is quite variable. Disease development is favored by low relative humidity, moderate temperatures, and succulent plant growth. Potential new fungicides were evaluated for disease control in a field trial conducted in the spring of 1994. In this study, Rally and Reach provided the highest level of disease control and highest percentages of marketable fruit when compared to untreated cantaloupe plants.
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Matheron, Michael E., and Martin Porchas. "Evaluation of New Fungicides for Management of Downy and Powdery Mildew of Lettuce in 1998." College of Agriculture, University of Arizona (Tucson, AZ), 1999. http://hdl.handle.net/10150/221659.
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Bremia lactucae and Erysiphe cichoracearum, respectively, cause downy and powdery mildew of lettuce. Cool moist environmental conditions favor the development of downy mildew, whereas warm and dry weather is conducive for powdery mildew. Several potential new fungicides were evaluated for control of these diseases of lettuce in 1998. The final severity of downy mildew in this trial was low. In addition to the standard compounds maneb, Aliette and Trilogy, several fungicides currently in development significantly reduced the severity of downy mildew compared to nontreated plants. These chemistries included Acrobat, RH -7281, an Unknown, Actigard, EF1295, Curzate, Quadris, BAS 500, QST 153, BAS 505 and BAS 490. Untreated lettuce plants were heavily infected with powdery mildew. In addition to the standard materials Microthiol Special and Trilogy, powdery mildew was significantly reduced on plants treated with BAS 490, BAS 505, EF1295, BAS 500 and Quadris. The possible availability of one or more of these chemistries under development for lettuce could help in efforts to develop and maintain a fungicide resistance management program for plant medicines of importance for this crop.
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Matheron, Michael E., and Martin Porchas. "Management of Downy and Powdery Mildew on Lettuce: Efficacy of Fungicides in 1996 Field Trial." College of Agriculture, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/214738.
Full textAbstract:
Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development ofdowny mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for management of these diseases in 1996. Both downy and powdery mildew developed in the test plots. All tested materials significantly reduced the severity of downy mildew compared to plants not treated with a fungicide. Compared to nontreated control plants as well as some tested materials and rates, significant reduction of powdery mildew was achieved with Azoxystrobin 80WDG + Latron B-1956, BAS 490 02F, Ciba G /MZ + Mancozeb 75DF, Dithane 75DF + Latron CS-7, Propamocarb 6EC (high rate), R11-7281 2F + Larron CS-7, and Microthiol 80WDG.
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Ellwood, Simon. "Characterisation of two powdery mildew diseases of Arabidopsis thaliana and positional cloning of a resistance gene." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302226.
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Olsen, M., S. Rasmussen, and C. Nischwitz. "Effect of fungicide treatments on incidence of powdery mildew of pecan and on pecan nut quality." College of Agriculture, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/226097.
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Powdery mildew of pecan, caused by Microsphaera ulni, was observed on pecan shucks by the latter part of June 2000 in a commercial pecan orchard near Sahuarita, Arizona. Results of 1999 studies indicated that infection does not reduce nut quality. In order to determine effects of fungicide treatments and to substantiate results from 1999, preventive applications of micronized sulfur and azoxystrobin were initiated on June 8, 2000 in selected clusters in both Wichita and Western varieties. Trials were established in plots that had a high incidence of powdery mildew in 1999. Whole nut weights, kernel weights, or color ratings were not significantly different among clusters of nuts that were treated with fungicides and untreated nuts that were infected with powdery mildew. Percent disease incidence was 100% in untreated clusters, 0% in clusters treated with azoxystrobin every two weeks, and 5.3% (Wichita) and 8.8% (Western) in clusters treated with sulfur three times early in the season. Results indicate that disease did not affect nut weight or quality and that early preventive fungicide treatments are effective in controlling infections.
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Quintana-Jones, Therese Angelica. "Evaluation of Drip Applications and Foliar Sprays of the Biocontrol Product Actinovate on Powdery Mildew and Other Fungal Diseases of Tomato." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/516.
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The effectiveness of the biocontrol product Actinovate® at enhancing tomato plant growth and yield, and reducing the presence of fungal pathogens was studied in greenhouse and field conditions. In the greenhouse, no differences were found among seed germination or plant survival rates, seedling heights, dry root weights, and dry shoot weights of tomato seedlings grown from seeds drenched with Actinovate® or Rootshield®. The effects of one initial Actinovate® seed drench at sowing, repeated applications through the drip irrigation throughout the season, or repeated applications through the drip irrigation plus foliar applications throughout the season at reducing plant infection by fungal plant pathogens, and increasing yield and quality for tomato plants (Solanum lycopersicum) were investigated in Los Alamos, CA, on a sandy loam soil. No significant differences in plant height were found among the four treatments. Marketable fruit weight was greater in the drip plus foliar treatment than in the Actinovate® seed drench treatment. The foliar plus drip treatment resulted in the greatest amount of powdery mildew present, although the disease pressure was low. No significant differences were found among the four treatments in the presence of Verticillium wilt or Sclerotinia.
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Matheron, Michael E., and Martin Porchas. "Field Evaluation of Potential New Fungicides for Control of Lettuce Downey and Powdery Mildew in 1994 and 1995." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/221462.
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Downy and powdery mildew are caused by the plant pathogenic fungi Bremia lactucae and Erysiphe cichoracearum, respectively. Cool and moist environmental conditions favor development of downy mildew, while warmer and dry weather is conducive for development of powdery mildew. Potential new fungicides were evaluated for control of these diseases during 1994 and 1995. In 1994, downy mildew did not occur in the test plots; however, powdery mildew was severe and was controlled most effectively by Microthiol. In the 1995 study, both downy and powdery mildew developed in the test plots. The highest level of downy mildew control was achieved with three experimental compounds, Fluazinam, Dimethomorph, and BAS-490. The most effective fungicides for control of powdery mildew in 1995 were BAS-490 and Microthiol.
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Freitas, José de. "APLICAÇÕES DE FUNGICIDAS EM DIFERENTES ESTÁDIOS DA CULTURA DA SOJA EM DOIS LOCAIS." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2012. http://tede2.uepg.br/jspui/handle/prefix/2227.
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Previous issue date: 2012-07-20The main diseases occurring in soybean (Glycine max) in Brazil have a great damage potential, requiring additional expenses to control through measures available today, highlighting the fungicides spray. The objective of this study was to evaluate the effect of fungicides spray at different growth stages of soybean, cultivar CD 206, and verify the relation between the severity of powdery mildew (Erysiphe diffusa) and of asian soybean rust (Phakopsora pachyrhizi), on yield components. Two experiments were conducted on field one in Arapoti (experiment I) and another in Ponta Grossa (experiment II) in the region of Campos Gerais, Paraná. In both local the fungicide was sprayed trifloxystrobin + cyproconazole, in a rate of 56,4 + 24,0 mL a. i. ha-1, was added ajduvante methyl ester of soybean oil in a rate of 360,0 mL a. i. ha-1. The experimental design was randomized blocks with four replications. The treatments in a total of ten, were composed of fungicides spray in different numbers and growth stages: Experiment I, 1. Control (no spray); 2. R5.2; 3. R4 + R5.2; 4. R2 + R4 + R5.2; 5. V9 + R2 + R4 + R5.2; 6. V6 + V9 + R2 + R4 + R5.2; 7. V6 + V9 + R2 + R4; 8. V6 + V9 + R2; 9. V6 + V9 and 10. V6. Experiment II, 1. Control (no spray); 2. R5.1; 3. R3 + R5.1; 4. R1 + R3 + R5.1; 5. V8 + R1 + R3 + R5.1; 6. V5 + V8 + R1 +R3 + R5.1, 7. V5 + V8 + R1 + R3; 8. V5 + V8 + R1; 9. V5 + V8 and 10. V5. The treatments were composed in order to generate and compare different percentages of severity of powdery mildew and asian soybean rust obtained by the period of protection or exposure to these diseases. The severity of powdery mildew was evaluated experiment I growth stages R2, R4, R5.3 and R5.5 and in experiment II in R1, R3, R5.2, R5.3 and R5.5. The severity of asian soybean rust was evaluated experiment I in growth at stages R5.3, R5.4, R6 and R7.1, and in experiment II R5.1, R5.2, R5.3, R5.5 and R6. With the data of severity it was calculated the area under the disease progress curve. Were also evaluated defoliation, yield and their components (number of pods per plant, number of grains per plant, grain weight per plant and thousand grain weight). Powdery mildew showed low severity. The asian soybean rust was the disease predominant in high severity, with high damage potential. The fungicides spray reduced disease severity and there was a negative linear relationship with the yield. Long periods without protection of plants allowed rapid reinfection of powdery mildew and spray erradicativas resulted in low efficiency of control powdery mildew and asian soybean rust. The fungicides spray between growth stages R1 to R5.2 promoted protection since the beginning of the epidemic and residual effect, que resulted in less severity, less defoliation, increased grain yield and higher yield.
As principais doenças que ocorrem na cultura da soja (Glycine max) no Brasil apresentam grande potencial de dano, exigindo gastos adicionais para o controle através das medidas disponíveis atualmente, destacando-se as aplicações de fungicidas. O objetivo deste trabalho foi avaliar o efeito das aplicações de fungicidas em diferentes estádios de desenvolvimento da soja, cultivar CD 206, e verificar a relação entre a severidade do oídio (Erysiphe diffusa) e da ferrugem asiática da soja (Phakopsora pachyrhizi), sobre componentes de produtividade. Foram conduzidos dois experimentos de campo, um em Arapoti (experimento I) e o outro em Ponta Grossa (experimento II), na região dos Campos Gerais do Paraná. Em ambos os locais foi aplicado o fungicida trifloxistrobina + ciproconazol, na dose de 56,4 + 24,0 mL i. a. ha-1, adicionado de ajduvante éster metílico de óleo de soja na dose de 360 mL i. a. ha-1. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. Os tratamentos em um total de dez, foram compostos de aplicações de fungicidas em diferentes números e estádios de desenvolvimento:Experimento I, 1. Testemunha (sem aplicação); 2. R5.2; 3. R4 + R5.2; 4. R2 + R4 +R5.2; 5. V9 + R2 + R4 + R5.2; 6. V6 + V9 + R2 + R4 + R5.2; 7. V6 + V9 + R2 + R4;8. V6 + V9 + R2; 9. V6 + V9 e 10. V6. Experimento II, 1. Testemunha (sem aplicação); 2. R5.1; 3. R3 + R5.1; 4. R1 + R3 + R5.1; 5. V8 + R1 + R3 + R5.1; 6. V5 + V8 + R1 + R3 + R5.1, 7. V5 + V8 + R1 + R3; 8. V5 + V8 + R1; 9. V5 + V8 e 10. V5. Os tratamentos foram compostos, a fim de gerar e comparar diferentes porcentagens de severidade de oídio e ferrugem asiática obtida pelo período de proteção ou exposição às estas doenças. A severidade do oídio foi avaliada no experimento I nos estádios de desenvolvimento R2, R4, R5.3 e R5.5 e no experimento II em R1, R3, R5.2, R5.3 e R5.5. A severidade da ferrugem asiática da soja foi avaliada no experimento I nos estádios de desenvolvimento R5.3, R5.4, R6 e R7.1, e no experimento II em R5.1, R5.2, R5.3, R5.5 e R6. Com os dados de severidade calculou-se a área abaixo da curva de progresso das doenças. Avaliouse também desfolha, produtividade e seus componentes (número de vagens por planta, número de grãos por planta, massa de grãos por planta e massa de mil grãos). O oídio apresentou baixa severidade. A ferrugem asiática foi a doença predominante em alta severidade, com alto potencial de dano. As aplicações de fungicidas reduziram a severidade das doenças e houve relação linear negativa com a produtividade. Longos períodos sem proteção das plantas permitiram reinfecção rápida do oídio e as aplicações erradicativas resultaram em baixa eficiência de controle do oídio e da ferrugem asiática. Aplicações do fungicida entre os estádios de desenvolvimento R1 a R5.2 promoveram proteção desde o início da epidemia e,efeito residual, resultaram em menor severidade, menor desfolha, maior massa de grãos e maior produtividade.
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Viljanen-Rollinson, S. L. H. "Expression and detection of quantitative resistance to Erysiphe pisi DC. in pea (Pisum sativum L.)." Lincoln University, 1996. http://hdl.handle.net/10182/1657.
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Characteristics of quantitative resistance in pea (Pisum sativum L.) to Erysiphe pisi DC, the pathogen causing powdery mildew, were investigated. Cultivars and seedlines of pea expressing quantitative resistance to E. pisi were identified and evaluated, by measuring the amounts of pathogen present on plant surfaces in field and glasshouse experiments. Disease severity on cv. Quantum was intermediate when compared with that on cv. Bolero (susceptible) and cv. Resal (resistant) in a field experiment. In glasshouse experiments, two groups of cultivars, one with a high degree of resistance and the other with nil to low degrees of resistance to E. pisi, were identified. This indicated either that a different mechanism of resistance applied in the two groups, or that there has been no previous selection for intermediate resistance. Several other cultivars expressing quantitative resistance were identified in a field experiment. Quantitative resistance in Quantum did not affect germination of E. pisi conidia, but reduced infection efficiency of conidia on this cultivar compared with cv. Pania (susceptible). Other epidemiological characteristics of quantitative resistance expression in Quantum relative to Pania were a 33% reduction in total conidium production and a 16% increase in time to maximum daily conidium production, both expressed on a colony area basis. In Bolero, the total conidium production was reduced relative to Pania, but the time to maximum spore production on a colony area basis was shorter. There were no differences between the cultivars in pathogen colony size or numbers of haustoria produced by the pathogen. Electron microscope studies suggested that haustoria in Quantum plants were smaller and less lobed than those in Pania plants and the surface area to volume ratios of the lobes and haustorial bodies were larger in Pania than in Quantum. The progress in time and spread in space of E. pisi was measured in field plots of cultivars Quantum, Pania and Bolero as disease severity (proportion of leaf area infected). Division of leaves (nodes) into three different age groups (young, medium, old) was necessary because of large variability in disease severity within plants. Disease severity on leaves at young nodes was less than 4% until the final assessment at 35 days after inoculation (dai). Exponential disease progress curves were fitted for leaves at medium nodes. Mean disease severity on medium nodes 12 dai was greatest (P<0.001) on Bolero and Pania (9.3 and 6.8% of leaf area infected respectively), and least on Quantum (1.6%). The mean disease relative growth rate was greatest (P<0.001) for Quantum, but was delayed compared to Pania and Bolero. Gompertz growth curves were fitted to disease progress data for leaves at old nodes. The asymptote was 78.2% of leaf area infected on Quantum, significantly lower (P<0.001) than on Bolero or Pania, which reached 100%. The point of inflection on Quantum occurred 22.8 dai, later (P<0.001) than on Pania (18.8 dai) and Bolero (18.3 dai), and the mean disease severity at the point of inflection was 28.8% for Quantum, less (P<0.00l) than on Pania (38.9%) or Bolero (38.5%). The average daily rates of increase in disease severity did not differ between the cultivars. Disease progress on Quantum was delayed compared with Pania and Bolero. Disease gradients from inoculum foci to 12 m were detected at early stages of the epidemic but the effects of background inoculum and the rate of disease progress were greater than the focus effect. Gradients flattened with time as the disease epidemic intensified, which was evident from the large isopathic rates (between 2.2 and 4.0 m d⁻¹) Some epidemiological variables expressed in controlled environments (low infection efficiency, low maximum daily spore production and long time to maximum spore production) that characterised quantitative resistance in Quantum were correlated with disease progress and spread in the field. These findings could be utilised in pea breeding programmes to identify parent lines from which quantitatively resistant progeny could be selected.
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Hayes, Matthew Allan. "Identification of host genes involved in the biotrophic interaction between grapevine and powdery mildew." 2006. http://hdl.handle.net/2440/37876.
Full textAbstract:
Grapevine powdery mildew is caused by Erysiphe necator, an Ascomycete fungus and an obligate biotroph restricted to growth on its grapevine host. Biotrophic pathogens form a stable association with host cells without directly causing cell death, and take up nutrients from, in the case of powdery mildew ( PM ), host epidermal cells ( Rumbolz et al., 2000 ). As the fungus grows, its increasing biomass becomes a strong nutrient sink capable of altering assimilate flow and storage in the host. To identify host genes that may mediate nutrient delivery to powdery mildew infected tissues and therefore may contribute to disease susceptibility, a candidate gene approach using degenerate and RT - PCR, and a nontargeted approach using microarray analysis was instigated. Once identified, " susceptibility genes " could be targeted for manipulation to provide alternative resistance strategies based on reduced susceptibility in the future. In addition to genes encoding pathogenesis and stress related proteins, microarray analysis revealed that transcript levels of a putative metal transporter and a cell wall structural protein were elevated in infected berry skin, while aquaporin water channels and genes associated with photosynthesis were generally repressed. Degenerate PCR was used to isolated new cell wall invertase, monosaccharide and amino acid transporter genes and initial RT - PCR revealed that expression of genes involved in sugar mobilisation were the most significantly modulated by powdery mildew infection. Previously unreported hexose transporters ( HTs ), ( VvHT3, VvHT4 and VvHT5 ) and a cwINV ( VvcwINV ) had been isolated from cDNA prepared from powdery mildew infected grapevine leaves. Full length clones of grapevine HTs and cwINV were obtained by RACE PCR. Heterologous expression of the three new HTs in yeast confirmed that VvHT4 and VvHT5 mediated glucose uptake, while VvHT3 did not function in the yeast system. However, transient expression of a translational fusion of the VvHT3 protein with green florescence protein in onion epidermal cells indicated that it is targeted to the plasma membrane of plant cells. Quantitative RT - PCR analysis of these new genes, together with previously reported grapevine HTs and cytoplasmic and vacuolar invertases, indicated that expression of VvcwINV and VvHT5, were significantly up - regulated by PM infection, while a vacuolar invertase was strongly down - regulated by PM infection. Invertase activity assays were in agreement with these findings, showing elevated sucrolytic activity in insoluble fractions and reduced sucrolytic activity in soluble fractions. These results suggest that apoplasmic phloem unloading of sucrose in the infected leaf is elevated and that VvHT5 is induced to recover the additional hexoses from the apoplasm. Basic localisation studies indicated that VvHT5 and VvcwINV are not induced specifically in powdery mildew infected leaf regions, but are induced in a more diffuse distribution within infected leaves. To determine if induction of VvHT5 and VvcwINV is specific to PM infection or if other stimuli may also mediate these responses, leaves were inoculated with downy mildew or stressed by wounding. Transcript levels of VvHT5 and VvcwINV were elevated by wounding and downy mildew infection, suggesting that the induction of these genes may be part of a general stress response. To explore the signalling pathways that may underlie these responses, leaves were treated with the plant growth regulators ethylene, jasmonate and abscisic acid. Exogenous application of ethylene and methyl jasmonate only marginally affected the expression of the genes studied, however foliar application of abscisic acid ( ABA ) induced gene expression changes similar to those observed in response to powdery mildew infection and wounding. Promoter sequences of VvHT3, VvHT4, VvHT5 and VvcwINV were isolated and analysed for the presence of regulatory elements. Compared with the promoters of VvHTs that were not induced by pathogen infection or wounding, the VvHT5 and VvcwINV promoters contained numerous motifs associated with induction by ABA including ABRE, Myc and Myb binding elements. The path of sugar loading into the mesocarp of grape berries during ripening is still poorly understood and few molecular components associated with this process have been described. Quantitative RT - PCR was used to monitor the expression of five HTs and VvcwINV during Cabernet sauvignon and Shiraz berry development and ripening. Of the three new HTs reported here, the expression of VvHT3 is most consistent with a potential role in sugar loading, while VvHT5 is induced late in this process. VvcwINV transcript levels were high pre - ripening and also during the later stages of ripening, therefore based on this expression pattern, a role for this enzyme during ripening is not clearly evident. These results are discussed in terms of an apoplasmic step in phloem unloading in ripening grape berries. This study has provided new insights into the molecular and biochemical processes associated with the formation of carbohydrate sink metabolism in response to stress stimuli, and sugar delivery to grape berries during ripening. ABA - dependant pathways may mediate the stress - associated induction of VvcwINV and VvHT5, presumably to recruit additional carbohydrates to the affected organ to energise repair and defence responses. At this stage it is unknown if this response is beneficial to pathogen nutrition, however potentially, modification of genes associated with carbohydrate sink metabolism could provide an alternative way to engineer resistance to this pathogen.Thesis (Ph.D.)--School of Agriculture, Food and Wine, 2006.
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Palmer, Sarah A. "Strawberry powdery mildew: epidemiology and the effect of host nutrition on disease." 2007. http://hdl.handle.net/2440/57974.
Full textAbstract:
Knowledge of disease epidemiology and the impact of plant nutrient status on development of disease is fundamental in establishing effective management strategies for crop pathogens such as Podosphaera aphanis Br. (Braun et al., 2002), the causal agent of powdery mildew on strawberries. The following study investigated the conditions conducive for powdery mildew in strawberry crops in South Australia, the effect of foliar concentration of potassium and calcium on yield and pathogen development on the strawberry cultivars Aromas (resistant to powdery mildew) and Selva (susceptible), the potential for use of foliar-applied potassium silicate to control disease and identification of genes differentially expressed during disease. Meteorological conditions associated with establishment of powdery mildew were observed over three consecutive seasons in commercial strawberry crops grown in Woodside, South Australia. Conducive conditions appear to be >28 oC, <55 % relative humidity (RH) with no rain during the day (for conidiation), followed by a night with >10 oC, >90 % RH and no rain (for germination). Colony development was then promoted by days of >15 oC and <70 % RH, with nights of >8 oC, >80 % RH and less than 2 mm rain in every 24 hour period. These are consistent with epidemiological studies of this pathogen (Peries, 1962a; Jhooty and McKeen, 1964; Mukerji, 1968; Perera and Wheeler, 1975; Byrne et al, 2000; Miller et al, 2003; Blanco et al, 2004; Davik and Honne, 2005; Amsalem et al, 2006). This knowledge may facilitate prediction of times considered high risk for establishment of powdery mildew in strawberry crops. Subsequently, this may allow optimisation of fungicide application and improved management of this disease and reduced yield loss and management expenses. P. aphanis developed at an increased rate on leaves of Selva with low calcium content compared with development on normally fertilised leaves. Increased numbers of conidia germinated successfully on leaves of Aromas with low calcium content compared with development on normally fertilised Aromas leaves, however, the germinated conidia still failed to develop into sporulating colonies. Potassium nutrition had no obvious effect on P. aphanis development. Foliar concentration found to be adequate for growth of cultivars, Selva and Aromas were 6.0 mg/g and 4.5 mg/g Calcium, dry weight and 11.0 mg/g and 12.5 mg/g potassium, dry weight (respectively). Potassium silicate, buffered to pH 7.0 and applied as a foliar fertiliser, reduced the severity of powdery mildew below the economic threshold, though not below the disease severity on plants treated with the fungicide, Systhane® (Bayer CropScience). As potassium silicate can be produced organically this compound may provide a useful management tool for both organic and conventional strawberry growers. Although the cultivar Aromas was not immune to disease under conducive conditions and high inoculum load in the field, inoculation of healthy Aromas plants with P. aphanis in the laboratory failed to produce disease. Conidia were seldom found attached to the leaf surface of healthy Aromas leaves. Germination and subsequent colony development were also not observed in inoculated samples. This suggests there is some mechanism of Aromas that inhibits development of this fungus. Preliminary investigation of differential expression in Aromas inoculated with P. aphanis, identified sequences with homology to a putative antimicrobial protein and photosynthesis-related genes. The results of these studies should enable growers to increase both crop yields and control of powdery mildew, one of the major economic diseases in South Australia. The epidemiological knowledge attained will be valuable, and may provide the basis for future forecast modelling for P. aphanis in strawberry crops in South Australia. Recommendations for calcium and potassium leaf content will allow growers to monitor their fertiliser regime for increased yield of these cultivars. Aromas was identified as a powdery mildew resistant cultivar potentially suitable for production in South Australia, and the genes associated with this resistance response may be used in studies of Fragaria species and breeding for powdery mildew resistant cultivars.http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297684
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2007
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Mafa, Maite Sarah. "Assessment of the effect of fungicides on powdery mildew development on butternut squash." Thesis, 2016. http://hdl.handle.net/11602/435.
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