Literatura científica selecionada sobre o tema "Primary inoculum"
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Artigos de revistas sobre o assunto "Primary inoculum"
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Deckers, T., e W. Porreye. "PRIMARY INOCULUM FORMATION OF ERWINIA AMYLOVORA". Acta Horticulturae, n.º 217 (novembro de 1987): 143–44. http://dx.doi.org/10.17660/actahortic.1987.217.20.
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Bailey, D. J., e C. A. Gilligan. "Dynamics of Primary and Secondary Infection in Take-All Epidemics". Phytopathology® 89, n.º 1 (janeiro de 1999): 84–91. http://dx.doi.org/10.1094/phyto.1999.89.1.84.
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Using a combination of experimentation and mathematical modeling, the effects of initial (particulate) inoculum density on the dynamics of disease resulting from primary and secondary infection of wheat by the take-all fungus, Gaeumannomyces graminis var. tritici, were tested. A relatively high inoculum density generated a disease progress curve that rose monotonically toward an asymptote. Reducing the initial inoculum density resulted in a curve that initially was monotonic, rising to a plateau, but which increased sigmoidally to an asymptotic level of disease thereafter. Changes in the infectivity of particulate inoculum over time were examined in a separate experiment. Using a model that incorporated terms for primary and secondary infection, inoculum decay, and host growth, we showed that both disease progress curves were consistent with consecutive phases dominated, respectively, by primary and secondary infection. We examined the spread of disease from a low particulate inoculum density on seminal and adventitious root systems separately. Although seminal roots were affected by consecutive phases of primary and secondary infection, adventitious roots were affected only by secondary infection. We showed that the characteristic features of disease progress in controlled experiments were consistent with field data from crops of winter wheat. We concluded that there is an initial phase of primary infection by G. graminis var. tritici on winter wheat as seminal roots grow through the soil and encounter inoculum, but the rate of primary infection slows progressively as inoculum decays. After the initial phase, there is an acceleration in the rate of secondary infection on both seminal and adventitious roots that is stimulated by the increase in the availability of infected tissue as a source of inoculum and the availability of susceptible tissue for infection.
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Lenhard, Justin R., e Zackery P. Bulman. "Inoculum effect of β-lactam antibiotics". Journal of Antimicrobial Chemotherapy 74, n.º 10 (6 de junho de 2019): 2825–43. http://dx.doi.org/10.1093/jac/dkz226.
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AbstractThe phenomenon of attenuated antibacterial activity at inocula above those utilized for susceptibility testing is referred to as the inoculum effect. Although the inoculum effect has been reported for several decades, it is currently debatable whether the inoculum effect is clinically significant. The aim of the present review was to consolidate currently available evidence to summarize which β-lactam drug classes demonstrate an inoculum effect against specific bacterial pathogens. Review of the literature showed that the majority of studies that evaluated the inoculum effect of β-lactams were in vitro investigations of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Haemophilus influenzae and Staphylococcus aureus. Across all five pathogens, cephalosporins consistently displayed observable inoculum effects in vitro, whereas carbapenems were less susceptible to an inoculum effect. A handful of animal studies were available that validated that the in vitro inoculum effect translates into attenuated pharmacodynamics of β-lactams in vivo. Only a few clinical investigations were available and suggested that an in vitro inoculum effect of cefazolin against MSSA may correspond to an increased likeliness of adverse clinical outcomes in patients receiving cefazolin for bacteraemia. The presence of β-lactamase enzymes was the primary mechanism responsible for an inoculum effect, but the observation of an inoculum effect in multiple pathogens lacking β-lactamase enzymes indicates that there are likely multiple mechanisms that may result in an inoculum effect. Further clinical studies are needed to better define whether interventions made in the clinic in response to organisms displaying an in vitro inoculum effect will optimize clinical outcomes.
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Kim, Seung-Han, Dong-Geun Kim, Jae-Tak Yoon, Sung-Gook Choi e Joon-Tak Lee. "Primary Inoculum of Strawberry Anthracnose in Nursing Field". Research in Plant Disease 8, n.º 4 (1 de dezembro de 2002): 228–33. http://dx.doi.org/10.5423/rpd.2002.8.4.228.
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LOPEZ-HERRERA, C. J. "Eradication of Primary Inoculum ofBotrytis cinereaby Soil Solarization". Plant Disease 78, n.º 6 (1994): 594. http://dx.doi.org/10.1094/pd-78-0594.
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Lung-Escarmant, Brigitte, e Dominique Guyon. "Temporal and Spatial Dynamics of Primary and Secondary Infection by Armillaria ostoyae in a Pinus pinaster Plantation". Phytopathology® 94, n.º 2 (fevereiro de 2004): 125–31. http://dx.doi.org/10.1094/phyto.2004.94.2.125.
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Epidemiological investigations were performed in a 3-ha maritime pine (Pinus pinaster) plantation established on a site heavily infested by Armillaria ostoyae. Geostatistics were used to examine the density and the distribution of the initial inoculum. Disease dynamics were monitored for 17 years after planting. On the whole site, the cumulative mortality rate reached 35% over this period, plateauing at 12 years. Disease progress curves differed according to the density of the initial inoculum, although in all the cases, the Gompertz model described the epidemics well. The epidemiological contributions of both primary (initially colonized stumps) and secondary inoculum (newly dead pines) were evaluated by analyzing their spatial relation to annual mortality. Newly dead pines acted as secondary inoculum from year 3 and their role increased with time. When the initial inoculum density was low, the contribution of secondary inoculum to epidemic development increased faster and halted sooner than when the density of primary inoculum was high. Regardless of its density, the primary inoculum acted throughout the dynamic phase of the epidemic. When the inoculum density was low, the probability of mortality during the first 6 years of the epidemic depended on the tree distance from the nearest stumps colonized by Armillaria sp. When the inoculum density was high, the probability of mortality was higher and not related to the distance between trees and colonized stumps.
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Van der Heyden, Hervé, Guillaume J. Bilodeau, Odile Carisse e Jean-Benoit Charron. "Monitoring of Peronospora destructor Primary and Secondary Inoculum by Real-Time qPCR". Plant Disease 104, n.º 12 (dezembro de 2020): 3183–91. http://dx.doi.org/10.1094/pdis-03-20-0687-re.
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Onion downy mildew (ODM), caused by Peronospora destructor, is a serious threat for onion growers worldwide. In southwestern Québec, Canada, a steady increase in occurrence of ODM has been observed since the mid-2000s. On onion, P. destructor can develop local and systemic infections producing numerous sporangia which act as initial inoculum locally and also for neighboring areas. It also produces oospores capable of surviving in soils and tissues for a prolonged period of time. A recent study showed that ODM epidemics are strongly associated with weather conditions related to production and survival of overwintering inoculum, stressing the need to understand the role of primary (initial) and secondary inoculum. However, P. destructor is an obligate biotrophic pathogen, which complicates the study of inoculum sources. This study aimed at developing a molecular assay specific to P. destructor, allowing its quantification in environmental samples. In this study, a reliable and sensitive hydrolysis probe-based assay multiplexed with an internal control was developed on the internal transcribed spacer (ITS) region to quantify soil- and airborne inoculum of P. destructor. The assay specificity was tested against 17 isolates of P. destructor obtained from different locations worldwide, other members of the order Peronosporales, and various onion pathogens. Validation with artificially inoculated soil and air samples suggested a sensitivity of less than 10 sporangia g−1 of dry soil and 1 sporangium m−3 of air. Validation with environmental air samples shows a linear relationship between microscopic and real-time quantitative PCR counts. In naturally infested soils, inoculum ranged from 0 to 162 sporangia equivalent g−1 of dry soil, which supported the hypothesis of overwintering under northern climates. This assay will be useful for primary and secondary inoculum monitoring to help characterize ODM epidemiology and could be used for daily tactical and short-term strategic decision-making.
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Safar, Korai M., Mahar R. Bux, Uqaili M. Aslam, Bhattacharjee A. Shankar e Ramesh K. Goel. "The feasibility of putrescible components of municipal solid waste for biomethane production at Hyderabad, Pakistan". Waste Management & Research: The Journal for a Sustainable Circular Economy 36, n.º 2 (9 de janeiro de 2018): 169–82. http://dx.doi.org/10.1177/0734242x17748363.
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This study analyzes the feasibility of putrescible components of municipal solid waste (PCMSW) such as food waste (FW) and yard waste (YW) for methane production in Pakistan. The batch experiments have been conducted at two different inoculums to substrate ratios (ISRs) by using various inoculums under mesophilic condition. The highest methane yield of FW and YW is achieved to be 428 Nml g-1 volatile solids (VS) added and 304 Nml g-1 VS added respectively by using buffalo dung inoculum at ISR-5. While, lowest methane yield of FW and YW is obtained as 236 Nml g-1 VS added and 151Nml g-1 VS added respectively by using effluent from a continuous stirrer tank reactor as inoculum at ISR-3. The first order decay model has been introduced, which gives best fit for methane potential of PCMSW with buffalo dung inoculum. Additionally, the feasibility of PCMSW in terms of power generation potential has been analyzed. About 60.63 million m3/year energy can be generated by converting PCMSW into methane gas leading to power generation. The finding of this study concludes that the replacement of imported energy and reduction up to 1.62% in other primary energy sources would be achieved, if PCMSW are properly converted into energy through anaerobic digestion in Pakistan.
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Khan, J., L. E. del Rio, R. Nelson, V. Rivera-Varas, G. A. Secor e M. F. R. Khan. "Survival, Dispersal, and Primary Infection Site for Cercospora beticola in Sugar Beet". Plant Disease 92, n.º 5 (maio de 2008): 741–45. http://dx.doi.org/10.1094/pdis-92-5-0741.
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Cercospora beticola survives as stromata in infected crop residue. Spores produced on these survival structures serve as primary inoculum during the next cropping season. This study was conducted to determine how long C. beticola can survive at different soil depths, the mechanism of inoculum dispersal, and the primary infection site in sugar beet. Longevity of C. beticola was studied over a 3-year period under field conditions at Fargo, ND. C. beticola-infected leaves were placed at depths of 0, 10, and 20 cm and retrieved after 10, 22, and 34 months. Survival of C. beticola inoculum declined with time and soil depth. Inoculum left on the soil surface, 0 cm in depth, survived the longest (22 months) compared with that buried at 10 cm (10 months) and 20 cm (10 months). C. beticola dispersal from the primary source of inoculum was studied in the field for three growing seasons. Sugar beet plants were surrounded with plastic cages with and without ground cover, or exposed with and without ground cover. Significantly higher disease severity was observed on exposed plants than caged plants with or without ground cover, suggesting that wind was the major dispersal factor for C. beticola inoculum. The primary infection site by C. beticola was determined in a greenhouse study. Leaves, roots, and stems of healthy sugar beet plants were inoculated with C. beticola. Cercospora leaf spot symptoms were observed only on plants that were leaf inoculated, suggesting that the leaf was the primary infection site for C. beticola.
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Gutierrez, W. A., H. D. Shew e T. A. Melton. "Sources of Inoculum and Management for Rhizoctonia solani Damping-off on Tobacco Transplants under Greenhouse Conditions". Plant Disease 81, n.º 6 (junho de 1997): 604–6. http://dx.doi.org/10.1094/pdis.1997.81.6.604.
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Damping-off and target spot are important diseases of tobacco transplants produced under greenhouse conditions. Identification of sources of inoculum for these diseases caused by Rhizoctonia solani is an important first step in disease management. Control strategies based on sanitation and the eradication of primary inoculum were studied. Potting mix and Styrofoam trays used in transplant production were assayed to determine if they were sources of primary inoculum. Eleven sources of potting mix were sampled over a 2-year period. None of the mixes contained viable inoculum of R. solani. R. solani was isolated from previously used trays after 1 year of storage by removing and plating pieces of Styrofoam from individual tray cells on alkaline water agar (AWA). Sclerotia and melanized hyphae of R. solani were observed in the cracks present in the cells of the trays. Dry heat (70 to 80°C for 2 h) and chemical (sodium hypochlorite and sodium chloride) treatments reduced the levels of inoculum on trays up to 45% compared to controls, but only methyl bromide and steam treatments (80°C for 0.5 to 2.0 h) eradicated inoculum of R. solani from trays. Elimination of primary inoculum from previously used trays effectively controlled target spot and stem rot diseases caused by R. solani.
Teses / dissertações sobre o assunto "Primary inoculum"
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Bailey, Douglas John. "The role of inoculum in the primary and secondary infection of certain plant pathogens". Thesis, Open University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388433.
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LEGLER, SARA ELISABETTA. "Biologia, epidemiologia e controllo della fase sessuale di Erysiphe necator, agente causale dell'oidio della vite". Doctoral thesis, Università Cattolica del Sacro Cuore, 2012. http://hdl.handle.net/10280/1312.
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Erysiphe necator (Schwein.) è l’agente causale dell’oidio della vite. Esso è in grado di svernare come ascospore all’interno di corpi fruttiferi, i chasmoteci, oppure come micelio in gemme infette. Le ascospore sono rilasciate nella primavera successiva e causano infezioni primarie che danno origine all’epidemia. Di conseguenza la riduzione dell’inoculo primario svernante potenzialmente riduce le epidemie nella stagione successiva.
I primi sei capitoli di questa tesi riguardano nuove conoscenze sulla biologia, epidemiologia e modellistica del patogeno. Due nuovi modelli meccanicistici che simulano, rispettivamente, la maturazione e dispersione dei chasmoteci e le infezioni ascosporiche sono stati sviluppati ed è stata studiata approfonditamente la dinamica di maturazione e dispersione delle ascospore stesse.
Nei restanti quattro capitoli il controllo del patogeno è stato riconsiderato in accordo con le linee guida della gestione integrata del vigneto. In particolare è stata valutata l’efficacia di diversi fungicidi, dell’iperparassita Ampelomyces spp. e di un olio minerale nel ridurre il numero di chasmoteci prodotti in autunno, nel distruggere gli stessi durante l’inverno e nel controllare le infezione primarie ascosporiche in primavera.Erysiphe necator (Schwein.) is the causal agent of grapevine powdery mildew. It survives the winter in two ways: as ascospores in overwintering fruiting bodies, the chasmothecia, and as mycelium in infected buds. Ascospores that are repeatedly released and cause primary infections in the following grapevine growing season and trigger powdery mildew epidemics. Consequently, the reduction of the overwintering inoculum may reduce powdery mildew epidemics in the next season. In order to verify this statement and develop sanitation as a relevant strategy to be used in integrated management of grape powdery mildew, different studies were performed during this Doctorate. The first six chapters of this dissertation pertain to new findings about the biology, epidemiology and modeling of the pathogen. A new mechanistic model predicting maturation and dispersal of chasmothecia was developed, dynamics of ascospore maturation and dispersal were studied and another mechanistic model simulating ascosporic infections was developed. In the last four chapters the control of the pathogen was redrawn according to the Integrated Pest Management concept: the efficacy of fungicides, the hyperparasite Ampelomyces spp., and mineral oil in reducing chasmothecia production in fall, in killing chasmothecia before bud break, and in controlling ascosporic infections in spring was investigated.
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LEGLER, SARA ELISABETTA. "Biologia, epidemiologia e controllo della fase sessuale di Erysiphe necator, agente causale dell'oidio della vite". Doctoral thesis, Università Cattolica del Sacro Cuore, 2012. http://hdl.handle.net/10280/1312.
Texto completo da fonteResumo:
Erysiphe necator (Schwein.) è l’agente causale dell’oidio della vite. Esso è in grado di svernare come ascospore all’interno di corpi fruttiferi, i chasmoteci, oppure come micelio in gemme infette. Le ascospore sono rilasciate nella primavera successiva e causano infezioni primarie che danno origine all’epidemia. Di conseguenza la riduzione dell’inoculo primario svernante potenzialmente riduce le epidemie nella stagione successiva.
I primi sei capitoli di questa tesi riguardano nuove conoscenze sulla biologia, epidemiologia e modellistica del patogeno. Due nuovi modelli meccanicistici che simulano, rispettivamente, la maturazione e dispersione dei chasmoteci e le infezioni ascosporiche sono stati sviluppati ed è stata studiata approfonditamente la dinamica di maturazione e dispersione delle ascospore stesse.
Nei restanti quattro capitoli il controllo del patogeno è stato riconsiderato in accordo con le linee guida della gestione integrata del vigneto. In particolare è stata valutata l’efficacia di diversi fungicidi, dell’iperparassita Ampelomyces spp. e di un olio minerale nel ridurre il numero di chasmoteci prodotti in autunno, nel distruggere gli stessi durante l’inverno e nel controllare le infezione primarie ascosporiche in primavera.Erysiphe necator (Schwein.) is the causal agent of grapevine powdery mildew. It survives the winter in two ways: as ascospores in overwintering fruiting bodies, the chasmothecia, and as mycelium in infected buds. Ascospores that are repeatedly released and cause primary infections in the following grapevine growing season and trigger powdery mildew epidemics. Consequently, the reduction of the overwintering inoculum may reduce powdery mildew epidemics in the next season. In order to verify this statement and develop sanitation as a relevant strategy to be used in integrated management of grape powdery mildew, different studies were performed during this Doctorate. The first six chapters of this dissertation pertain to new findings about the biology, epidemiology and modeling of the pathogen. A new mechanistic model predicting maturation and dispersal of chasmothecia was developed, dynamics of ascospore maturation and dispersal were studied and another mechanistic model simulating ascosporic infections was developed. In the last four chapters the control of the pathogen was redrawn according to the Integrated Pest Management concept: the efficacy of fungicides, the hyperparasite Ampelomyces spp., and mineral oil in reducing chasmothecia production in fall, in killing chasmothecia before bud break, and in controlling ascosporic infections in spring was investigated.
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Nazareno, Nilceu Ricetti Xavier de. "Influence of infected corn residue as a source of primary inoculum of Cercospora zeae-maydis (Tehon and Daniels) the cause of gray leaf spot of corn /". The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759914762668.
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Jacometti, Marco Alexander Azon. "Enhancing ecosystem services in vineyards to improve the management of Botrytis cinerea". Phd thesis, Lincoln University. Bio-Protection and Ecology Division, 2007. http://theses.lincoln.ac.nz/public/adt-NZLIU20070126.115223/.
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Organic mulches and cover crops mulched in situ were assessed for their effects on B. cinerea primary inoculum and disease levels in inflorescences at flowering and/or bunches at harvest.
Organic mulches were used to enhance biological degradation of vine debris to reduce levels of B. cinerea primary inoculum the following season. Four mulch types (anaerobically and aerobically fermented marc (grape pressings), inter-row grass clippings and shredded office paper) were applied under ten-year-old Riesling vines in a ten-replicate randomized block design in New Zealand over two consecutive years. Plastic mesh bags, each containing naturally infected vine debris, were placed under vines on bare ground (control) and at the soil-mulch interface, in winter (July) 2003 and 2004. In each year, half the bags were recovered at flowering (December) and the remainder at leaf plucking (February), for assessment of B. cinerea sporulation from the vine debris and debris degradation rate. Bait lamina probes, which measure soil biological activity, were placed in the soil-mulch interface three weeks before each of the two bag-recovery dates in both years and were then removed and assessed at the same times as were the bags. All mulches led to a reduction in B. cinerea sporulation. This reduction was significantly correlated with elevated rates of vine debris decomposition and increased soil biological activity. Over both years, compared with the controls, all treatments gave a 3-20-fold reduction in B. cinerea sporulation, a 1.6-2.6-fold increase in vine debris degradation and in the two marc and the paper treatments, a 1.8-4-fold increase in activity of soil organisms.
The mulches also altered vine characteristics and elevated their resistance to B. cinerea through changes to the soil environment. Functional soil biological activity, as measured by Biolog Ecoplates and bait lamina probes, was increased 2-4 times in the two marc and paper treatments, compared with the control, an effect relating to the elevated soil moisture and reduced temperature fluctuations under these mulches. Soil nutrient levels and the C:N ratios were also affected in these treatments. The mulched paper lowered vine canopy density by up to 1.4 times that of the other treatments, an effect which probably led to elevated light penetration into the canopy and consequent increased canopy temperature, photosynthesis and lowered canopy humidity. These changes to soil and vine characteristics increased grape skin strength by up to 10% in the paper treatment and sugar concentrations by 1.2-1.4 °Brix in the two marc and paper treatments. The severity of B. cinerea infections in the anaerobic marc, aerobic marc and paper treatments were reduced to 12%, 3% and 2.2% of the control, respectively, in field assessments averaged over two consecutive harvests.
Cover crops mulched in situ had similar effects to those of the organic mulches, increasing soil biological activity and reducing B. cinerea primary inoculum and the severity of B. cinerea infection in grapes at harvest (2006). Inter-row phacelia and ryegrass were mulched in winter 2005 and compared with a bare ground control, under 10-year-old Chardonnay vines in a ten-replicate randomized block design. Functional soil biological activity increased by 1.5-4.5 times in the two cover crop treatments compared with the control, an effect possibly related to elevated soil moisture in these treatments. This increase in soil moisture and soil biological activity increased vine debris degradation, reduced B. cinerea primary inoculum on the debris and decreased B. cinerea severity at flowering (December 2005) and harvest (April 2006).
These results show the potential of organic mulches and cover crops mulched in situ to enhance soil ecosystem services and improve the sustainability of viticultural practices.
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ONESTI, GIOVANNI. "Studi sulle dinamiche dell'inoculo di Guignardia bidwellii, agente causale del marciume nero della vite". Doctoral thesis, Università Cattolica del Sacro Cuore, 2016. http://hdl.handle.net/10280/10799.
Texto completo da fonteResumo:
L’ascomicete Guignardia bidwellii, agente causale del marciume nero della vite, è un patogeno economicamente importante in alcuni areali viticoli. La conoscenza, disponibile sul marciume nero dell’uva, è stata recuperata dalla letteratura, analizzata e sintetizzata per sviluppare un modello meccanicistico del ciclo di vita del patogeno, guidata dalle variabili meteorologiche e dalla fenologia della vite, e basata sull'analisi dei sistemi. Il modello è stato poi valutato per la sua capacità di rappresentare il sistema reale e la sua utilità per la comprensione di epidemie di marciume nero su foglie e grappoli in un vigneto del Nord Italia, nel 2013 al 2015. Successivamente, le mancanze di conoscenza sono state analizzate, studiate e quindi colmate attraverso specifici esperimenti. In un primo passo, le dinamiche dell’inoculo primario e dei modelli di dispersione (di entrambi ascospore e conidi) da mummie svernate sono state studiate in un vigneto sperimentale per tre anni. In un secondo passo, l'effetto della temperatura e dell'umidità sulla formazione di picnidi di G. bidwellii e la successiva estrusione di cirri, nelle lesioni su foglia, la produzione e la germinazione dei conidi (inoculo secondario), e la lunghezza del periodo di latenza sono stati studiati sia in condizioni di campo che in ambiente controllato. In un terzo passo, sono stati condotti studi in ambiente controllato per studiare la produzione di conidi di G. bidwellii sulle lesioni di foglie, influenzata da lavaggi ripetuti e alternando periodi di secco ed umido. Il modello epidemiologico sviluppato in questa tesi può essere utilizzata da viticoltori come strumento predittivo per la pianificazione di trattamenti fungicidi nei vigneti.The ascomycete Guignardia bidwellii, causal agent of black-rot on grapevines, is an economically important pathogen in some viticultural areas. The available knowledge on black-rot of grape was retrieved from literature, analyzed, and synthesized to develop a mechanistic model of the life cycle of the pathogen, driven by weather and vine phenology, and based on the systems analysis. The model was then evaluated for its ability to represent the real system and its usefulness for understanding black-rot epidemics on leaves and bunches in a vineyard of north Italy, in 2013 to 2015. Thereafter, weaknesses in our knowledge were analysed and studied through specific experiments. In a first step, dynamics of primary inoculum and dispersal patterns (both ascospores and conidia) from overwintered grape mummies were investigated in an experimental vineyard during three years. In a second step, the effect of temperature and humidity on the formation of G. bidwellii pycnidia and the extrusion of cirri in grape leaf lesions, production and germination of conidia (secondary inoculum), and the length of the latency period were studied under both environmental and controlled conditions. In a third step, environmental-controlled studies were conducted to investigate the production course of G. bidwellii conidia on grape leaf lesions as influenced by repeated washing events and alternate dry and wet periods. The model developed in this thesis can be used by vinegrowers as a predictive tool for scheduling fungicide sprays in the vineyards.
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ONESTI, GIOVANNI. "Studi sulle dinamiche dell'inoculo di Guignardia bidwellii, agente causale del marciume nero della vite". Doctoral thesis, Università Cattolica del Sacro Cuore, 2016. http://hdl.handle.net/10280/10799.
Texto completo da fonteResumo:
L’ascomicete Guignardia bidwellii, agente causale del marciume nero della vite, è un patogeno economicamente importante in alcuni areali viticoli. La conoscenza, disponibile sul marciume nero dell’uva, è stata recuperata dalla letteratura, analizzata e sintetizzata per sviluppare un modello meccanicistico del ciclo di vita del patogeno, guidata dalle variabili meteorologiche e dalla fenologia della vite, e basata sull'analisi dei sistemi. Il modello è stato poi valutato per la sua capacità di rappresentare il sistema reale e la sua utilità per la comprensione di epidemie di marciume nero su foglie e grappoli in un vigneto del Nord Italia, nel 2013 al 2015. Successivamente, le mancanze di conoscenza sono state analizzate, studiate e quindi colmate attraverso specifici esperimenti. In un primo passo, le dinamiche dell’inoculo primario e dei modelli di dispersione (di entrambi ascospore e conidi) da mummie svernate sono state studiate in un vigneto sperimentale per tre anni. In un secondo passo, l'effetto della temperatura e dell'umidità sulla formazione di picnidi di G. bidwellii e la successiva estrusione di cirri, nelle lesioni su foglia, la produzione e la germinazione dei conidi (inoculo secondario), e la lunghezza del periodo di latenza sono stati studiati sia in condizioni di campo che in ambiente controllato. In un terzo passo, sono stati condotti studi in ambiente controllato per studiare la produzione di conidi di G. bidwellii sulle lesioni di foglie, influenzata da lavaggi ripetuti e alternando periodi di secco ed umido. Il modello epidemiologico sviluppato in questa tesi può essere utilizzata da viticoltori come strumento predittivo per la pianificazione di trattamenti fungicidi nei vigneti.The ascomycete Guignardia bidwellii, causal agent of black-rot on grapevines, is an economically important pathogen in some viticultural areas. The available knowledge on black-rot of grape was retrieved from literature, analyzed, and synthesized to develop a mechanistic model of the life cycle of the pathogen, driven by weather and vine phenology, and based on the systems analysis. The model was then evaluated for its ability to represent the real system and its usefulness for understanding black-rot epidemics on leaves and bunches in a vineyard of north Italy, in 2013 to 2015. Thereafter, weaknesses in our knowledge were analysed and studied through specific experiments. In a first step, dynamics of primary inoculum and dispersal patterns (both ascospores and conidia) from overwintered grape mummies were investigated in an experimental vineyard during three years. In a second step, the effect of temperature and humidity on the formation of G. bidwellii pycnidia and the extrusion of cirri in grape leaf lesions, production and germination of conidia (secondary inoculum), and the length of the latency period were studied under both environmental and controlled conditions. In a third step, environmental-controlled studies were conducted to investigate the production course of G. bidwellii conidia on grape leaf lesions as influenced by repeated washing events and alternate dry and wet periods. The model developed in this thesis can be used by vinegrowers as a predictive tool for scheduling fungicide sprays in the vineyards.
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Schneider, Olivier. "Analyse des effets du mode de gestion des résidus de colza sur l'initiation du cycle de Leptosphaeria maculans". Paris, Institut national d'agronomie de Paris Grignon, 2005. http://www.theses.fr/2005INAP0007.
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Huang, G. F., e 黃見發. "The Identification of Fusarium Wilt of Asparagus Bean and Its Primary Inoculum". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/38561710598876683309.
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碩士國立中興大學
植物病理學系
84
The purpose of this study is to determine the cause of a previously undignosed wilt of asparagus bean ( Vigna sesquipedalis ) and its primary inoculum in fields. Based on completion of Kock's Postulates, this disease was proved to be caused by Fusarium oxysporum f. sp. tracheiphilum ( Fot ) in Taiwan. The fungus ( isolate F42 from Taiwan ) had the same reactions as Fot race 3 ( isolate T-89-15 from U. S. A. )when inoculated to the differential varieties of cowpea ( Vigna sinensis ). Both isolates were pathonic to the susceptible variery ''BE-5'' , whereas they can not attack the resistant variety ''BE-88'' , in the greenhouse inoculation tests. Moreover, their cultural characteristics were quite similar on potato dextrose agar ( PDA ) . Therefore, Taiwanese Fot ( isolate F42 ) was identified as race 3. The optimum temperature and pH value for mycelial growth of the pathogen were 28 ℃ and 7 on PDA, respectively. Howere , the optimum temperature for the disease development was 32 ℃by root-prunning inoculation metd. The isolates were made from rhizosphere soils collected from many asparagus bean fields on pentachloronitrobenzene ( PCNB ) medium and resulted that Fot was only found in fields Tachia and Likang I that had continously cropped asparagus bean and had Fusarium wilt for years. The soil samples from other fields that were new to asparagus bean failed to yield Fot. Especially, Fusarium wilt of asparagus bean occurred in field Likang III that never had asparagus bean before and the cultivation was managed by ooding method. The disease rates were 23, 8 and 11 ％ at early, middle and late growth stages of asparagus bean, reapectively, which was not different significantly according to the stastistical analysis. Moreover, 8 - 20 ％of Fot isolated from seeds by placing on Komada selective medium or from seedlings grown in pathogen-free soil in greenhouse, but none was obtained from surface-disinfected seeds in these experiments. All evidences were in favor of seed transmission of this disease in Taiwan. In more advce experiments, unrippening pods were removed from diseased plants and isolations were made from their pedicel, funicle, vascular, pulp and seeds. For was found in pulp, vascular and seeds but not in pedicel and funicle. Moreover, out of 350 seeds, only 1 % yielded Fot. Resistant screenings of 21 asparagus bean varieties/lines to Fot by using root-pruning inoculation method indicated that lines ''14-3'', ''20-4'' and ''80-10'' had disease severity less than 13.3.
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Adee, Eric Allen. "Primary inoculum of Pyrenophora tritici-repentis on wheat as affected by cultural controls in reduced tillage, and its effect on epidemic development". 1988. http://hdl.handle.net/2097/22689.
Texto completo da fonteCapítulos de livros sobre o assunto "Primary inoculum"
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Schoeny, Alexandra, Stéphane Jumel, François Rouault, Christophe Le May e Bernard Tivoli. "Assessment of airborne primary inoculum availability and modelling of disease onset of ascochyta blight in field peas". In Ascochyta blights of grain legumes, 87–97. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6065-6_9.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Primary inoculum"
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Rai, U., Y. Bharath, V. Shetty, J. H. Patil e M. A. Raj. "Kinetics of anaerobic digestion of water hyacinth using primary sludge as inoculum". In 2011 International Conference on Green Technology and Environmental Conservation (GTEC 2011). IEEE, 2011. http://dx.doi.org/10.1109/gtec.2011.6167658.
Texto completo da fonteRelatórios de organizações sobre o assunto "Primary inoculum"
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Freeman, Stanley, e Daniel Legard. Epidemiology and Etiology of Colletotrichum Species Causing Strawberry Diseases. United States Department of Agriculture, setembro de 2001. http://dx.doi.org/10.32747/2001.7695845.bard.
Texto completo da fonteResumo:
Diseases caused by Colletotrichum spp. are one of the most important limitations on international strawberry production, affecting all vegetative and fruiting parts of the plant. From 1995 to 1997, C. acutatum infections reached epidemic levels in Israeli strawberry nurseries, causing extensive loss of transplants in fruit-bearing fields and additional reductions in yield. Although C. acutatum also occurs on strawberry in Florida, recent crown rot epidemics have been primarily caused by C. gloeosporioides. Little is known about the basic epidemiology of these important diseases on strawberry. The source of initial inoculum for epidemics in Israel, Florida (other US states including California) and the rest of the world is not well understood. Subspecies relationships between Colletotrichum isolates that cause the different diseases on strawberry (i.e. attack different tissues) are also not well understood. Objectives of this proposal were to detennine the potential of infested soil, strawberry debris and other hosts as sources of primary inoculum for strawberry diseases caused by Colletotrichum spp. in Israel and Florida. In addition, traditional (ie. morphological characteristics, benomyl sensitivity, vegetative compatibility grouping) and DNA based methods were used to investigate the etiology of these diseases in order to resolve epidemiologically important subspecies variation. In Israel it was found that C. gloeosporioides and C. acutatum infecting strawberry could remain viable in sterilized soil for up to one year and in methyl-bromide fumigated soil for up to 4 months; inoculum in mummified fruit remained viable for at least 5 months under field conditions whereas that in infected crowns was not recovered. Therefore, the contribution of these inocula to disease epidemics should be considered. The host range and specificity of C. acutatum from strawberry was examined on pepper, eggplant, tomato, bean and strawberry under greenhouse conditions. The fungus was recovered from all plant species over a three-month period but caused disease symptoms only on strawberry. C. acutatum was also isolated from healthy looking, asymptomatic plants of the weed species, Vicia and Conyza, growing in infected strawberry fruiting fields. Isolates of C. acutatum originating from strawberry and anemone infected both plant species in artificial inoculations. The habitation of a large number of plant species including weeds by C. acutatum suggests that although it causes disease only on strawberry and anemone in Israel, these plants may serve as a potential inoculum source for strawberry infection and pennit survival of the pathogen between seasons. In Florida, isolates of Colletotrichum spp. from diseased strawberry fruit and crowns were evaluated to detennine their etiology and the genetic diversity of the pathogens. Only C. acutatum was recovered from fruit and C. gloeosporioides were the main species recovered from crowns. These isolates were evaluated at 40 putative genetic loci using random amplified polymorphic DNA (RAPD). Genetic analysis of RAPD markers revealed that the level of linkage disequilibrium among polymorphic loci in C. gloeosporioides suggested that they were a sexually reproducing population. Under field conditions in Florida, it was detennined that C. gloeosporioides in buried crowns survived
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Katan, Jaacov, e Michael E. Stanghellini. Clinical (Major) and Subclinical (Minor) Root-Infecting Pathogens in Plant Growth Substrates, and Integrated Strategies for their Control. United States Department of Agriculture, outubro de 1993. http://dx.doi.org/10.32747/1993.7568089.bard.
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In intensive agriculture, harmful soilborne biotic agents, cause severe damage. These include both typical soilborne (clinical) major pathogens which destroy plants (e.g. Fusarium and Phytophthora pathogens), and subclinical ("minor") pathogens (e.g. Olpidium and Pythium). The latter cause growth retardation and yield decline. The objectives of this study were: (1) To study the behavior of clinical (major) and subclinical (minor) pathogens in plant growth substrate, with emphasis on zoosporic fungi, such as Pythium, Olipidium and Polymyxa. (2) To study the interaction between subclinical pathogens and plants, and those aspects of Pythium biology which are relevant to these systems. (3) To adopt a holistic-integrated approach for control that includes both eradicative and protective measures, based on a knowledge of the pathogens' biology. Zoospores were demonstrated as the primary, if not the sole propagule, responsible for pathogen spread in a recirculating hydroponic cultural system, as verified with P. aphanidermatum and Phytophthora capsici. P. aphanidermatum, in contrast to Phytophthora capsici, can also spread by hyphae from plant-to-plant. Synthetic surfactants, when added to the recirculating nutrient solutions provided 100% control of root rot of peppers by these fungi without any detrimental effects on plant growth or yield. A bacterium which produced a biosurfactant was proved as efficacious as synthetic surfactants in the control of zoosporic plant pathogens in the recirculating hydroponic cultural system. The biosurfactant was identified as a rhamnolipid. Olpidium and Polymyxa are widespread and were determined as subclinical pathogens since they cause growth retardation but no plant mortality. Pythium can induce both phenomena and is an occasional subclinical pathogen. Physiological and ultrastructural studies of the interaction between Olpidium and melon plants showed that this pathogen is not destructive but affects root hairs, respiration and plant nutrition. The infected roots constitute an amplified sink competing with the shoots and eventually leading to growth retardation. Space solarization, by solar heating of the greenhouse, is effective in the sanitation of the greenhouse from residual inoculum and should be used as a component in disease management, along with other strategies.