Dissertations / Theses on the topic 'Dieback'
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Evans, David Paul. "Biological indicators of forest dieback." Thesis, University of South Wales, 1992. https://pure.southwales.ac.uk/en/studentthesis/biological-indicators-of-forest-dieback(514886c2-00a0-4280-aca2-a500e3e794cb).html.
Full textNobrega, Caroline Correa. "Amazon forest dieback: assessing vulnerabilities and threats." Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/5873.
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In recent years, it is increasing evidences about Amazon vunerability due to land use and climate changes. Because of a positive feedback system, in which impacts intensify other impacts, some models project to the end of the century a replacement of the Amazon forest by savanna formations or semi-arid (forest dieback). Several evidence has indicated a high vulnerability of the Amazon to global climate change and local environmental impacts triggered by human activities (eg conversion to agricultural areas, construction of roads and burns). However, they are still deeply unknown the general mechanisms and standards about how these impacts affect the forest. In this thesis, I developed works that aim contribute to discussions of the subject. In each chapter, I will consider a threat that is contributing to the degradation of the Amazon. Each of the three threats discussed in the following chapters are often cited as important drivers of forest dieback. In the first chapter I evaluated the impact of forest fires at different levels of diversity of trees in a forest area next to the Amazon-Cerrado transition. Our results suggest that communities of trees in burned areas are losing more phylogenetic and functional diversity per unit of species than in unburned areas. My results indicate the existence of selection of species based on phylogenetic and functional characteristics, representing a major force of change and impoverishment (functional and phylogenetically) of these communities. In the second chapter, using high resolution images (LiDAR and hyperspectral), I evaluated the impact of a intense drought in forest areas near Madre de Dios, Peru. Thus, my results support the idea that changes in regional climate may change the structure and function of the forest. In the third chapter, I evaluated how the construction of roads in the Brazilian Amazon has contributed to deforestation in an important group of protected areas of the Amazon: the Indigenous Lands. Based on the analysis of observed impacts, I propose the establishment of buffer zones (buffers) around these reserves to reduce the negative impacts of road construction planned to be built.
Nos últimos anos, tem surgido cada vez mais evidências que a Amazônia pode estar ameaçada em decorrências das mudanças regionais no clima e no uso do solo. Por causa de um sistema de retroalimentação positivo, em que impactos intensificam outros impactos, alguns modelos projetam para o final do século uma substituição da floresta amazônica por formações tipo savana ou semiáridas (forest dieback). Diversas evidências têm indicado uma alta vulnerabilidade da Amazônia às mudanças climáticas globais e aos impactos ambientais locais desencadeados por atividades humanas (e.g. conversão de áreas para agropecuária, construção de estradas e queimadas). Entretanto, são ainda profundamente desconhecidos os mecanismos e padrões gerais de como esses impactos afetam a floresta. Nesta tese, desenvolvi trabalhos que têm como objetivo contribuir para as discussões do tema. Em cada capítulo, abordarei uma ameaça que, de alguma forma, está contribuindo para a degradação da Amazônia. Cada uma das três ameaças discutidas nos próximos capítulos são, frequentemente, apontadas como importantes propulsores de forest dieback. No primeiro capítulo avaliei o impacto de incêndios florestais em diferentes níveis de diversidade de árvores de uma área florestal próxima à transição Amazônia-Cerrado. Nossos resultados sugerem que as comunidades de árvores das áreas queimadas estão perdendo mais diversidade filogenética e funcional por unidade de espécie do que nas áreas não queimadas. Nossos resultados indicam a existência de seleção de espécies com base em características filogenéticas e funcionais, que representam uma importante força de mudança e de empobrecimento (funcional e filogeneticamente) dessas comunidades. No segundo capítulo, usando imagens de alta resolução (LiDAR e hiperespectral), eu avaliei o impacto de um período de seca em áreas florestais próximas a Madre de Dios, Peru. Nossos resultados dão suporte a hipótese de que mudanças no clima regional modificam a estrutura e função da floresta. No terceiro capítulo, eu avaliarei de que forma a construção de estradas na Amazônia brasileira tem contribuído para o desmatamento que incide em um importante grupo de áreas protegidas da Amazônia: as Terras Indígenas. Com base na análise dos impactos observados, nós propomos o estabelecimento de zonas de amortecimento (buffers) em torno dessas reservas para reduzir os impactos negativos da construção de estradas planejadas para serem construídas.
Hill, Louise. "Ecological impacts of ash dieback in Great Britain." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:941ee684-798b-47b6-ae51-64baeb5f821e.
Full textLardner, Richard. "Early diagnosis and detection of Eutypa dieback of grapevines." Title page, table of contents and abstract only, 2003. http://hdl.handle.net/2440/37969.
Full textThesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2003.
Raiter, Keren. "Bush tucker and dieback : the threat of dieback caused by Phytophthora cinnamomi to plants of significance to Noongar people of Western Australia's south coast." Thesis, Raiter, Keren (2005) Bush tucker and dieback : the threat of dieback caused by Phytophthora cinnamomi to plants of significance to Noongar people of Western Australia's south coast. Honours thesis, Murdoch University, 2005. https://researchrepository.murdoch.edu.au/id/eprint/32600/.
Full textRolshausen, Philippe. "Biology and control of Eutypa dieback of grapevine in California /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
Full textSingh, Gurpreet. "Identification of Quantitative Trait Loci (QTL) associated with resistance to Vascular Streak Dieback disease of cacao." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/29254.
Full textCujec, Thomas Peter. "Incidence, etiology and epidemiology of stonefruit dieback in the Okanagan Valley." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27865.
Full textLand and Food Systems, Faculty of
Graduate
Reich, Richard William. "Causes of dieback of Douglas-fir in the interior of B.C." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29780.
Full textForestry, Faculty of
Graduate
Khattab, Islam Maged Abdelazeem [Verfasser], and P. [Akademischer Betreuer] Nick. "Ancestral Grapes with Resistance against Dieback: Molecular and Functional Analysis of Plant-pathogen Crosstalk in the Context of Botryosphaeriaceae Related Dieback / Islam Maged Abdelazeem Khattab ; Betreuer: P. Nick." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1231361654/34.
Full textMwitwa, Jacob Pacific. "Growth and physiological parameters related to shoot dieback in Pterocarpus angolensis DC seedlings." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/20431.
Full textENGLISH ABSTRACT:Six experiments, five in the glasshouse and one in the field near Nelspruit, were carried out to ascertain the effect of factors related to shoot die-back, and of water treatments on the growth and physiological responses of Pterocarpus angolensis seedlings. The study was undertaken to broaden the knowledge and understanding of the phenomenon of shoot die-back in order to enhance our ability to regenerate the species. The following experiments were carried out (a) Assessment of biomass accumulation; anatomical characteristics of the shoot apical meristem; foliar, stem and root concentration of micro- and macronutrients associated with each phenophase, (b) Effect of seedling age and seed source on the occurrence of shoot die-back under field conditions; (c) Water treatment effects on ChI. afluorescence traits of£'. angolensis seedlings obtained by assessing the fluorescence yield of photosynthetic samples subjected to dark- and light-adaptation; (d) Genetic variation in shoot die-back and other traits of sixteen halfsib families of £.. angolensis from Malawi, Namibia and Zambia grown over two die-back seasons. Experiments conducted revealed the following 1. Patterns of growth observed in phenophases are indicators of seasonal changes in annual biomass allocation to the shoot and root. Phenophases such as leaf loss and stem senescence, whether shoot die-back occurs completely or not, are directly related to the decline in above-ground biomass and declined rate of increase in root biomass respectively. Leaf flush, expansion and maturation result in increased biomass accumulation whilst shoot die-back has a minimal downregulatory effect on root biomass accumulation compared to the shoot. Shoot dieback is not sudden, therefore from the first day of germination, seedlings synchronise growth and development with the occurrence of shoot die-back. 2. Phenophasic concentration of foliar N, Ca and Mg, stem Fe and Cu and root concentrations of P, K, Mg, Fe and B are associated with shoot die-back. Patterns of mineral nutrient concentration obtained in foliage and roots but to a lesser extent in the stem, may be related to nutrient remobilisation during shoot dieback. Higher relative mineral nutrient changes during leaf yellowing and shoot die-back may be an indication of the removal of significant volumes of mobile nutrients from senescing tissues. 3. The volume of the shoot apex of E. angolensis remains constant during different phenophases which points to seasonal uniformity in the size of the apical dome. Changes in phenology associated with declined growth, or shoot die-back, is revealed through declined cell number in the tunica which is a reflection of declined mitotic activity. 4. Shoot die-back occurs in all seedlings from nursery stock planted under field conditions and all seedlings of up to two years experience complete shoot dieback. Shoot die-back takes place irrespective of seed source or the age of nursery stock that is planted. Survival after the first shoot die-back is normally low. Water treatments had no significant effect on the function of PSIJ reaction centres of P. angolensis nursery seedlings. In the case of both dark- and light-adapted leaves, water treatment had no significant effect on the measured Chi. a fluorescence parameters or the calculated parameters (specific activities, phenomenological fluxes, structure-function and performance indexes and drivingforces). 5. Water treatments affect the shape of ChI. a fluorescence transients of lightadapted compared to that of dark-adapted photosynthetic samples of E. angolensis. No significant water treatment effect was obtained for extracted and technical Chi. afluorescence parameters, specific fluxes, quantum efficiencies and phenomenological fluxes. Quantum yield, relative electron transport and quantum yield limitation, de-excitation rate constants, structure-function, performance indexes and driving forces were also not significantly different across water treatments.6. Genetic variation was observed to exist among 16 halfsib families from Malawi, Namibia and Zambia. High heritabilities were obtained for shoot die-back and other traits, indicating that shoot die-back is genetically controlled. The trait is passed from parents to offspring and it is highly probable that it occurs, throughout its natural range, in all seedlings. Since shoot die-back is genetically programmed, it remains crucial to the ability of a seedling to regenerate in the following rainy season
AFRIKAANSE OPSOMMING:Ses eksperimente, vyf in die glashuis en een in die veld naby Nelspruit, is uitgevoer om die effek van faktore wat verwant is aan die terugsterwing van lote op saailinge, sowel as om die effek van waterstres op die groei en fisiologiese responsies van Pterocarpus angolensis saailinge, te ondersoek. Die studie is ondemeem om die kennis en begrip aangaande die regenerasie-dinamika van die spesies te verbeter. Die volgende eksperimente is uitgevoer: (a) Evaluering van die effek van jisiologiese veranderings op biomassa; blaar-, stam- en wortelkonsentrasies van spoor- en makro-voedingselemente, en anatomiese eienskappe van die apikale meristeem van die lote. (b) Effek van saailingouderdom en saadbron op die voorkoms van lootterugsterwing onder veldtoestande. (c) Waterbehandelingseffekte op Chi. ajluorisensie eienskappe van ,e. angolensis saailinge wat verkry is deur die jluorisensie te evalueer van fotosintesemonsters wat aan donker- en lig-adaptasies onderwerp is. (d) Genetiese variasie in loot-terugsterwing en ander groei-eienskappe van 16 halfsib families van ,e. angolensis vanaf Malawi, Namibia en Zambia wat gekweek is oor twee terugsterj-seisoene. Die eksperimente het die volgende aan die lig gebring: 1. Groeipatrone waargeneem gedurende die fenofases is indikatore van seisoenale veranderings in jaarlikse biomassa allokasies aan die loot en die wortels. Fenofases soos blaarverlies en lootafsterwing, ongeag of loot-terugsterwing volledig is of nie, is direk verwant aan die afname in bogrondse biomassa en afnemende tempo van toename in wortelbiomassa respektiewelik. Bottende blare, vergroting en rypwording van blare lei tot toenemende biomassa akkumulasie terwyl loot-terugsterwing 'n minimale afskalende effek op akkumulasie van wortelbiomassa het in vergelyking met die van die loot. Loot-terugsterwing is nie skielik, met ander woorde vanaf die eerste dag van ontkieming sinchroniseer saailinge groei en ontwikkeling met die voorkoms van loot-terugsterwing. 2. Fenofase konsentrasies van en veranderings in blaar N en Ca en loot Fe, asook veranderings in waargenome wortel N, K, Ca, Mn, Cu, Zn en B is sterk geassosieer met loot-terugsterwing. Patrone van minerale voedingselementkonsentrasies wat in blare en wortels, en in minder mate in die loot, verkry is, mag direk verwant wees aan hermobilisering van voedingselemente gedurende loot-terugsterwing. Hoe relatiewe minerale voedingselementveranderings gedurende die vergeling van blare en lootterugsterwing mag 'n indikasie wees van die verwydering van betekenisvoUe hoeveelhede mobiele nutriente vanaf sterwende weefsel. 3. Die volume van die groeipunt van r. angolensis bly konstant gedurende verskillende fenofases wat dui op seisoenale uniformiteit in die grootte van die apikale koepel. Veranderings in fenologie ge-assosieer met afnemende groei, of loot-terugsterwing, word gerejlekteer deur afnemende selgetaUe in die tunika wat dui op afnemende mitotiese aktiwiteit. 4. VoUedige loot-terugsterwing kom voor in aUe saailinge vanaf die kwekery wat in die veld geplant word tot op die ouderdom van twee iaar. Dit kom voor angeag van saadbron of ouderdom van saailinge ten tye van planting. Oorlewing na aanvanklike loot-terugsterwing is normaalweg laag. 5. Water behandelings het geen beduidende effek op die funksie van PSII reaksiesentra van r. angolensis kewekery-saailinge gehad. Vir beide donker- en lig-aangepaste blare is geen beduidende waterbehandelingseffek verkry vir waargenome ChI. a jluoresensie parameters of die berekende parameters (spes ifieke aktiwiteite, jenomenologiese jlukse, struktuur-funksie-indekse, "perjormance-indekse oj" driving forces" ). 6. Genetiese variasie tussen 16 halfsibfamilies vanaf Malawi, Namibie en Zambie is verkry vir loot-terugsterwing en ander groei-eienskappe. Dit dui op genetiese beheer van terugsterwing en dat die eienskap oorerjbaar is, en waarskynlik in die hele natuurlike verspreidingsgebied van die spesies in aUe saailinge voorkom. Aangesien loot-terugsterwing gene ties geprogrammeer is, is dit noodsaaklik vir die vermoe van die plant om in die volgende reenseisoen te regenereer.
Evans, Paul M. "Dynamics of forest ecosystem properties and resilience in a temperate woodland undergoing dieback." Thesis, Bournemouth University, 2018. http://eprints.bournemouth.ac.uk/30829/.
Full textBunny, F. "The biology, ecology and taxonomy of Phytophthora citricola in native plant communities in Western Australia /." Access via Murdoch University Digital Theses Project, 1996. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20061122.122739.
Full textBusch, Sarah Ann. "Cellular and molecular strategies to overcome macrophage-mediated axonal dieback after spinal cord injury." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1252273911.
Full textBunny, Felicity J. "The biology, ecology and taxonomy of Phytophthora citricola in native plant communities in Western Australia." Thesis, Bunny, Felicity J. (1996) The biology, ecology and taxonomy of Phytophthora citricola in native plant communities in Western Australia. PhD thesis, Murdoch University, 1996. https://researchrepository.murdoch.edu.au/id/eprint/492/.
Full textBunny, Felicity J. "The biology, ecology and taxonomy of Phytophthora citricola in native plant communities in Western Australia." Murdoch University, 1996. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20061122.122739.
Full textNejad, Pajand. "Pathogenic and ice-nucleation active (INA) bacteria causing dieback of willows in short rotation forestry /." Uppsala : Dept. of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200524.pdf.
Full textNewby, Zoe Joy. "Quantification of the risk of Phytophthora dieback in The Greater Blue Mountains World Heritage area." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/10286.
Full textCarter, Judith. "Vegetation attributes that influence the mardo (Antechinus flavipes leucogaster) in healthy, dieback affected and rehabilitated forest." Thesis, Carter, Judith (2003) Vegetation attributes that influence the mardo (Antechinus flavipes leucogaster) in healthy, dieback affected and rehabilitated forest. Honours thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/32627/.
Full textSeebacher, Tanya Marie. "Western redcedar dieback : possible links to climate change and implications for forest management on Vancouver Island, B.C." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/32352.
Full textForestry, Faculty of
Graduate
Cambours, Marie-Anne. "Frost-related dieback of Swedish and Estonian Salix plantations due to pathogenic and ice nucleation-active bacteria /." Uppsala : Plant Pathology and Biocontrol Unit, Swedish University of Agricultural Sciences, 2004. http://epsilon.slu.se/9600090.pdf.
Full textAdu-Acheampong, Richard Kwame. "Pathogen diversity and host resistance in dieback disease of cocoa caused by Fusarium decemcellulare and Lasiodiplodia theobromae." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4670.
Full textSchmull, Michaela. "Site factors determining epiphytic lichen distribution in a dieback affected spruce fir forest on Whiteface Mountain, New York." Doctoral thesis, [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965267318.
Full textBrèteau-Amores, Sandrine. "Economic analysis of adaptation options toward drought-induced risk of forest dieback : financial balance and/or carbon balance." Thesis, Université de Lorraine, 2020. http://www.theses.fr/2020LORR0158.
Full textForests are ecosystems that play an important role in the adaptation of the society to climate change. They provide ecosystem services that contribute to human well-being and reduce social vulnerability. Presently, the pace of climate change is accelerating too fast for the natural and spontaneous forest adaptation process to offset many negative impacts of climate-induced changes, such as increased frequency, duration, and intensity of mean and extreme natural events like severe drought events. In France, the extreme drought events of 1976, 2003 and 2018 caused great damage to the forest, both immediately and long after the drought episodes. Private owners can protect their forests through adaptation strategies. Different management-based adaptation strategies are recommended in order to improve the water consumption efficiency of the forest stand and thus its resistance to drought risk. Market-based strategies may be another option. Four types of adaptation strategies were tested and compared, from an economic perspective, in this thesis. These are: incremental (reduction of rotation length and reduction of stand density), transitional (composition diversification and structure diversification) and transformational (species substitution) management-based adaptation as well as a market-based adaptation (index-based insurance). For that purpose, outputs from forest growth models were used as inputs for forest economics analysis, and an index-based insurance model was developed and simulated. The main results of this thesis, for the considered case studies and under some assumptions, can be summarized as follows. First, the results proved that adaptation is a relevant strategy to mitigate drought-induced risk of dieback by the implementation of either management-based adaptation or market-based adaptation. Second, combining different management-based adaptation strategies appeared as a relevant way to adapt forests in a context of an increasing drought-induced risk of forest dieback. Indeed, the combination of different strategies was found to be more beneficial for the forest owner than each strategy implemented separately. However, not all adaptation options appeared effective, i.e., maladaptation. Finally, while forest insurance contracts covering drought-induced risk of forest dieback could be a relevant market-based option, small gains associated with current contracts are likely to prevent forest owners from adopting such insurance products
Sollars, Elizabeth. "The genome and epigenome of the European ash tree (Fraxinus excelsior)." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25977.
Full textJordan, Stephen Andrew. "Epidemiology and etiology of Eutypa dieback of grapevine and partial characterization of Eutypella vitis, a new pathogen of grapevine." Diss., Connect to online resource - MSU authorized users, 2008.
Find full textPilbeam, Ros. "Effects of phosphite on disease development and histological responses in Eucalyptus marginata infected with Phytophthora cinnamomi." Thesis, Pilbeam, Ros (2003) Effects of phosphite on disease development and histological responses in Eucalyptus marginata infected with Phytophthora cinnamomi. PhD thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/260/.
Full textPilbeam, Ros. "Effects of phosphite on disease development and histological responses in Eucalyptus marginata infected with Phytophthora cinnamomi." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040820.140206.
Full textKotze, Louis Jacobus Daniel. "Risk assessment of the Acacia cyclops dieback pathogen, Pseudolagarobasidium acaciicola, as a mycoherbicide in the South African strandveld and limestone fynbos." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86551.
Full textENGLISH ABSTRACT: Acacia cyclops, an invasive weed in South Africa, was initially imported to stabilize the sand dunes in the southern Cape. The spread of A. cyclops is a major threat to the fragile biodiversity of the strandveld and limestone fynbos vegetation. Acacia cyclops dieback has been observed for some time, although the causative agent, Pseudolagarobasidium acaciicola, has only recently been described. This fungus is nominated for development as a mycoherbicide to control A. cyclops. Although current biological and mechanical control efforts are proving to be partially effective, A. cyclops is still causing major damage to natural ecosystems. The introduction of a mycoherbicide would increase the cost effectiveness of controlling this weed in the long term. The majority of the literature that was reviewed supports the use of mycoherbicides as biocontrol agents, especially when taking into account the decrease in acceptance and availability of chemical control agents. Considering that the Pseudolagarobasidium genus consists of saprobes, opportunistic facultative pathogens and endophytes, P. acaciicola is predicted to have similar biological characteristics. The species is also highly likely to be indigenous, although with a wider distribution range than previously envisaged. Strict precautions should still however be taken to ensure that non-target species will not be threatened. This study consists of a unique risk assessment comprising different sections. A field survey was performed to record disease incidence among indigenous woody plant species around 100 diseased A. cyclops trees. Subsequently, DNA extractions were made from the roots of the diseased indigenous plants and A. cyclops trees to verify the presence of P. acaciicola. Of the 2432 indigenous woody plants observed, 22 (0.9%) were dead or dying, while P. acaciicola was detected in 10 of these (0.4%), representing six species. Pseudolagarobasidium acaciicola was detected in 47% of the A. cyclops trees. Although P. acaciicola could be a weak pathogen in a broad range of indigenous plant species, the extremely low disease incidence is an indication of a low level of risk associated with using P. acaciicola as a mycoherbicide. Additionally, pathogenicity trials on indigenous plant species were conducted to give an indication of host susceptibility. A total of 30 indigenous plant species were wound inoculated at two field sites, and potted plants representing 17 indigenous plant species were wound and soil inoculated in a nursery. The optimum growth temperature for P. acaciicola was determined in order to understand it’s seasonal and landscape preference. Mortality was recorded in five of nine indigenous Fabaceae species, while a single plant each of four other non-Fabaceae species died after inoculation. No plants outside the Fabaceae family died in the field. Only A. cyclops seedlings died following soil inoculation. Longitudinal sections of stem inoculated plants revealed no systemic infection in Fabaceae species that survived inoculation. Infection in susceptible Fabaceae species was generally more extensive than infection in susceptible non-Fabaceae species. The optimum growth rate for P. acaciicola was determined at 35°C, indicating an adaptation to summer conditions. Indigenous Fabaceae species do display greater susceptibility than species from other families, indicating some level of specificity, although susceptible species can not be phylogenetically circumscribed. Aside from being a facultative pathogen on A. cyclops, results from this study suggest that P. acaciicola is primarily a saprophyte and an occasional opportunistic pathogen on some indigenous Fabaceae, possibly only being a weak opportunistic pathogen on some non-Fabaceae species. However, the risk of not effectively managing A. cyclops populations in these threatened vegetation types outweighs the risk associated with using P. acaciicola as a mycoherbicide. Therefore the use of P. acaciicola as a mycoherbicide on A. cyclops would be recommended, provided that sufficient monitoring of treated sites is implemented that primarily focus on the indigenous Fabaceae species. The effective control of A. cyclops could be achieved when P. acaciicola is used to compliment current mechanical, biological and chemical control methods in an integrated management strategy.
AFRIKAANSE OPSOMMING: Acacia cyclops, ook bekend as rooikrans, is ‘n indringerplant in Suid-Afrika wat oorspronklik vanaf Australië ingevoer is om die sandduine in die Kaap te stabiliseer. Die verspreiding van rooikrans bedreig die sensitiewe biodiversiteit van die strandveld en kalksteen fynbos. Rooikrans terugsterwing is al vir ‘n geruime tyd opvallend in die grootste deel van die plant se verspreiding in Suid-Afrika, alhoewel die veroorsakende organisme, Pseudolagarobasidium acaciicola, eers onlangs beskryf is. Hierdie swam is as ‘n geskikte kandidaat vir die ontwikkeling van ‘n biologiese onkruiddoder om rooikrans te beheer, genomineer. Alhoewel die huidige biologiese- en meganiese beheer metodes vir rooikrans gedeeltelik suksesvol is, hou dié indringer steeds ‘n ernstige bedreiging vir die natuurlike ekosisteme in. Die gebruik van ‘n swam-gebaseerde onkruiddoder sal die beheer van rooikrans oor die langtermyn meer koste-effektief maak. Die oorgrote meerderheid van die literatuur wat hersien is, ondersteun die gebruik van swam-gebaseerde onkruiddoders as biologiese beheermiddels, veral as die afname in aanvaarbaarheid en beskikbaarheid van chemiese beheermiddels in ag geneem word. Aangesien die Pseudolagarobasidium genus uit saprofiete, opportunistiese fakultatiewe patogene en endofiete bestaan, word daar voorspel dat P. acaciicola ‘n soortgelyke biologiese karakter sal hê. Dit is hoogs waarskynlik dat hierdie swamspesie inheems is, alhoewel die verspreiding wyer mag wees as wat oorspronklik voorspel is. Streng maatreëls moet egter steeds in plek wees om te verseker dat nie-teiken plantspesies nie bedreig word nie. Hierdie studie bestaan uit ‘n unieke risiko-analise met verkeie onderafdelings. ‘n Veld-opname is uitgevoer om die siekte-voorkoms van die inheemse houtagtige plantspesies rondom ‘n 100 siek rooikrans plante te bepaal. DNA ekstraksies is vervolgens vanuit die wortels van siek inheemse plantspesies en -rooikrans uitgevoer, om uiteindelik die teenwoordigheid van P. acaciicola binne die hout te kon bevestig. Uit ‘n totaal van 2432 inheemse houtagtige plante wat aangeteken is, was 22 (0.9%) siek of dood, terwyl die teenwoordigheid van P. acaciicola in 10 van hierdie plante (0.4%), wat ses spesies teenwoordig, bevestig is. Die teewoordigheid van P. acaciicola is ook in 47% van die rooikrans bevestig. Alhoewel P. acaciicola moontlik ‘n swak opportunistiese patogeen op ‘n verskeidenheid inheemse plantspesies is, dui die lae verhouding van dooie inheemse plante teenoor gesonde plante in die veld op ‘n lae risiko vir die gebruik van P. acaciicola as ‘n biologiese onkruiddoder. Patogenisiteitstoetse is op inheemse plantspesies uitgevoer om ‘n aanduiding van gasheervatbaarheid te verkry. Wond-inokulasies is op ‘n totaal van 30 inheemse plantspesies by twee veldstudie-areas uitgevoer, terwyl wond- en grond-inokulasies op 17 inheemse spesies potplante in die kweekhuis uitgevoer is. Die optimale temperatuur waarby P. acaciicola groei, is bepaal om die swam se seisoenale- en habitatsvoorkeure beter te verstaan. Plante van vyf uit die nege inheemse Fabaceae spesies het doodgegaan, terwyl ‘n enkele plant van vier nie-Fabaceae spesies doodgegaan het. Alle plante buite die Fabaceae familie het oorleef in die veld na inokulasie. Slegs rooikranssaailinge het na grond inokulasie doodgegaan. Lengtedeursnee van die stam en wortels van elke geïnokuleerde plant het bevestig dat daar geen sistemiese infeksie in Fabaceae spesies wat inokulasie oorleef het, plaasgevind het nie. Infeksies in vatbare Fabaceae spesies was oor die algemeen meer ernstig as infeksies in vatbare nie-Fabaceae spesies. Die optimale groei van P. acaciicola het by 35°C plaasgevind, wat aandui op ‘n voorkeur vir somerstoestande. Inheemse Fabaceae spesies het meer vatbaar as vatbare plantspesies van ander families voorgekom. Hierdie verskynsel dui op ‘n sekere vlak van spesifisiteit, alhoewel daar geen duidelike filogenetiese grense vir vatbare spesies bepaal kon word nie. Behalwe vir die feit dat P. acaciicola ‘n fakultatiewe patogeen op rooikrans is, stel resultate van hierdie studie voor dat hierdie swam hoofsaaklik ‘n saprofiet is wat soms ook ‘n opportunisties patogeen op sekere inheemse Fabaceae is en moontlik slegs ‘n swak opportunistiese patogeen op plantspesies buite die Fabaceae familie is. Die swak en oneffektiewe bestuur van rooikrans in hierdie bedreigde plantegroeitipes hou egter ‘n groter bedreiging in as die gebruik van P. acaciicola as ‘n biologiese onkruiddoder. Pseudolagarobasidium acaciicola word daarom aanbeveel vir die beheer van rooikrans, mits voldoende monitering, wat fokus op inheemse Fabaceae spesies, gepaard gaan met die gebruik van hierdie biologiese onkruiddoder. Rooikrans kan effektief beheer word as P. acaciicola ingespan word om huidige meganiese-, biologiese- en chemiese beheermetodes in ‘n geïntegreerde bestuurstrategie te komplimenteer.
Hesse, Volker. "Epiphytic lichen diversity and its dependence on chemical site factors in differently elevated dieback-affected spruce stands of the Harz Mountains /." Berlin : J. Cramer, 2002. http://catalogue.bnf.fr/ark:/12148/cb41308907z.
Full textGraham, Tristian. "The impact of Phytophthora dieback and the aerial application of phosphite on terrestrial invertebrate communities of south coast heathlands, Western Australia." Thesis, Graham, Tristian (2003) The impact of Phytophthora dieback and the aerial application of phosphite on terrestrial invertebrate communities of south coast heathlands, Western Australia. Honours thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/32628/.
Full textHarada, Yota. "Climate-driven mangrove dieback in the Gulf of Carpentaria, Australia: using stable isotopes as a tool to assess and monitor ecosystem changes." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/393196.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
McDougall, Keith L. "Vegetation patterns in the northern jarrah forest of Western Australia in relation to dieback history and the current distribution of Phytophthora cinnamomi." Thesis, McDougall, Keith L. (1996) Vegetation patterns in the northern jarrah forest of Western Australia in relation to dieback history and the current distribution of Phytophthora cinnamomi. PhD thesis, Murdoch University, 1996. https://researchrepository.murdoch.edu.au/id/eprint/51870/.
Full textLaidlaw, William Scott, and mikewood@deakin edu au. "The Effects of Phytophthora Cinnamomi on heathland flora and fauna of the Eastern Otway Ranges." Deakin University. School of Biological and Chemical Sciences, 1997. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051111.121612.
Full textau, M. Wheeler@murdoch edu, and Margaret Wheeler. "Reproductive and Molecular Biology of Eucalyptus marginata." Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040723.140250.
Full textEpaina, Peter. "Identification of Molecular Markers and Quantitative Trait Loci linked to resistance to Vascular Streak Dieback and Phytophthora pod rot of Cacao Theobroma cacao L)." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/10060.
Full textFoggo, Andrew. "The biology and ecology of the ash bud moth Prays fraxinella Bjerk. with special reference to its role in the dieback of hedgerow ash trees." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314876.
Full textSafodien, Sieyaam. "The molecular identification and characterisation of Eutypa dieback and a PCR-based assay for the detection of Eutypa and Botryosphaeriaceae species from grapevine in South Africa." Thesis, Stellenbosch : Stellenbosch University, 2007. http://hdl.handle.net/10019.1/21757.
Full textENGLISH ABSTRACT: Grapevine trunk diseases are caused by invasive pathogens that are responsible for the slow decline of vines. In particular, Eutypa dieback of grapevine has had a devastating impact on vineyards worldwide, reducing growth and yield, eventually killing the grapevine. The causal organism of Eutypa dieback was first described as Eutypa armeniacae Hansf. & Carter, the pathogen that causes dieback of apricots, but since 1987 this species has been considered a synonym of Eutypa lata (Pers.:Fr.) Tul & C. Tul (anamorph Libertella blepharis A. L. Smith). Recently, it was proposed that at least two species that are capable of infecting grapevines are responsible for Eutypa dieback. Consequently, the molecular identification and characterisation of Eutypa dieback was used to delineate the species occurring on infected grapevines in South Africa. This involved the molecular analyses of three molecular markers, namely, the internal transcribed spacer (ITS) and large subunit (LSU) regions of the ribosomal DNA operon, and the -tubulin gene. The results obtained revealed the presence of a second species, namely, Eutypa leptoplaca (Mont.) Rappaz, that occurred together with E. lata on infected grapevines. Also co-habiting with these pathogens were related fungi form the Diatrypaceae family, Cryptovalsa ampelina (Nitschke) Fuckel and Eutypella vitis (Schwein.) Ellis & Everhart. Pathogenicity tests conducted on isolates representing C. ampelina, E. lata, E. leptoplaca, and E. vitis revealed that all were pathogenic to grapevine. Several species of Botryosphaeriaceae that commonly invade the woody tissue of grapevines are also pathogenic to grapevine. The symptoms in grapevine commonly associated with Botryosphaeriaceae are easily confused with the symptoms produced by Eutypa dieback which prompted the need for the development of a detection method that can correctly identify the presence of multiple pathogens. A reverse dot blot hybridisation (RDBH) method was subsequently applied to provide a rapid, accurate and reliable means of detecting the Eutypa species involved in the Eutypa disease complex, as well as those species of Botryosphaeriaceae known to cause disease in grapevines. The method involved the use of multiplex PCR to simultaneously amplify and label the regions of DNA that are used as pathogen specific probes. Consequently, membrane immobilised species-specific oligonucleotides synthesised from the ITS, - tubulin and LSU molecular data were evaluated during the application of this diagnostic method to detect Eutypa species. It was found that the species-specific oligonucleotides, designed from ITS sequence data, could consistently detect E. lata and E. leptoplaca. The application of the RDBH method for the detection of these Eutypa species, based on -tubulin and LSU sequence data, however, proved to be unsuccessful. Subsequently, a RDBH method, utilising species-specific oligonucleotides designed from elongation factor-1α sequence data, was successfully applied for the detection of Botyrosphaeria dothidea (Moug.:Fr.) Ces. & De Not., Neofusicoccum luteum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers, A.J.L. Phillips and Neofusicoccum ribis (Slippers, Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips. The method, however, was unsuccessful for the detection of Diplodia seriata De Not. In addition to the above-mentioned shortcomings, the RDBH was not amenable to the detection of pathogens directly from field or environmental samples, but required preparation of DNA from pure cultures. The method, however, allows for the identification of multiple pathogens in a single assay. As DNA extraction methods are amended, improved and honed to obtain DNA from environmental samples, so would it increase the usefulness of RDBH.
AFRIKAANSE OPSOMMING: Wingerd stamsiektes word veroorsaak deur patogene wat die vermoë het om wingerdplante te infekteer en dan stadige agteruitgang van dié wingerde te veroorsaak. Veral Eutypa terugsterwing het ‘n vernietigende effek op wingerde wêreldwyd deurdat dit groeikrag en oesmassa verlaag, maar ook omdat dit uiteindelik wingerdstokke kan dood. Die veroorsakende organisme is aanvanklik as Eutypa armeniacae Hansf. & Carter beskryf, die patogeen wat terugsterf by appelkose veroorsaak, maar sedert 1987 word hierdie spesies beskou as ‘n sinoniem van Eutypa lata (Pers.:Fr.) Tul & C. Tul (anamorph Libertella blepharis A. L. Smith). Dit is egter onlangs voorgestel dat ten minste twee spesies die vermoë het om wingerd te infekteer om Eutypa terugsterwing te veroorsaak. Gevolglik is molekulêre identifikasie- en karakteriseringstudies geloods om te bepaal watter spesies Eutypa terugsterwing in Suid-Afrikaanse wingerde veroorsaak. Dit het die molekulêre analise van drie molekulêre merkers behels, naamlik die interne getranskribeerde spasiëerderarea (“ITS”), die groot ribosomale subeenheid (“LSU rDNA”) en β-tubilien geen. Resultate van die filogenetiese analise dui daarop dat ’n tweede spesies, naamlik Eutypa leptoplaca (Mont.) Rappaz, saam met E. lata in geïnfekteerde plante voorkom. Saam met bogenoemde twee spesies het daar ook verwante spesies van die Diatrypaceae familie voorgekom, naamlik Cryptovalsa ampelina (Nitschke) Fuckel en Eutypella vitis (Schwein.) Ellis & Everhart. Patogenisiteitstudies wat uitgevoer is met verteenwoordigende isolate van C. ampelina, E. lata, E. leptoplaca, en E. vitis dui daarop dat almal patogene van wingerd is. Verskeie Botryosphaeriaceae spesies wat gereeld in houtagtige wingerdweefsel aangetref word, is ook patogene van wingerd. Interne simptome wat algemeen met Botryosphaeriaceae infeksies geassosieer word, kan baie maklik met dié van Eutypa terugsterwing verwar word en dit het die nood laat ontstaan om ‘n opsporingsmetode te ontwikkel wat akkuraat genoeg is om tussen veelvoudige infeksies te onderskei. ’n Omgekeerde-stippelklad-hibridisasie (OSH) metode is gevolglik aangewend om Eutypa spesies betrokke in die Eutypa-siektekompleks op ‘n vinnige, akkurate en betroubare manier op te spoor, sowel as die Botryosphaeriaceae species wat bekend is as patogene van wingerd. Die metode behels ’n saamgestelde PKR vir die vermeerdering en merk van DNS areas wat gebruik word as patogeen spesifieke peilers. Spesies-spesifieke oligonukleotiede ontwikkel vanaf die ITS, -tubilien en LSU molekulêre data is op ‘n membraan vasgeheg en gebruik om ’n diagnostiese toets te ontwikkel vir Eutypa species. Merkers ontwikkel vanaf die ITS kon E. lata and E. leptoplaca konsekwent opspoor. Die opspoor van Eutypa spesies met merkers vanaf die -tubulien en LSU gene met OSH was onsuksesvol. Die OSH metode met merkers vanaf die verlengingsfaktor-1α kon susksesvol gebruik word om Botyrosphaeria dothidea (Moug.:Fr.) Ces. & De Not., Neofusicoccum luteum (Pennycook & Samuels) Crous, Slippers & A.J.L. Phillips, Neofusicoccum parvum (Pennycook & Samuels) Crous, Slippers, A.J.L. Phillips and Neofusicoccum ribis (Slippers, Crous & M.J. Wingf.) Crous, Slippers & A.J.L. Phillips op te spoor. Dié metode kon egter nie Diplodia seriata De Not. opspoor nie. Bykomend tot bogenoemde tekortkominge, kon die omgekeerde-stippelklad-hibridisasie metode ook nie aangepas word om patogene direk vanuit plantmateriaal op te spoor nie en word DNS afkomstig vanaf suiwer kulture benodig. Dié metode laat egter identifikasie van verskeie patogene in ‘n enkele toets toe. Soos DNS ekstraksie metodes aangepas, verbeter en verfyn word om DNS vanuit plantmateriaal te verkry, sal die bruikbaarheid van die omgekeerde stippelklad hibridisasie metode ook verbeter.
Needham, Jessica. "Harnessing demographic data for cross-scale analysis of forest dynamics." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:156850fa-3148-45a6-b2f8-ada9dd3f6a7f.
Full textHorn, Kevin Paul. "An Investigation of the Role of Macrophages in Spinal Cord Injury and Repair." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1249267954.
Full textGarms, Mareike [Verfasser], Hubert [Akademischer Betreuer] Job, Marius [Gutachter] Mayer, and Hubert [Gutachter] Job. "Perception of climate-induced forest dieback and silvicultural adaptation to climate change in mountain forests - The case of the Bavarian Forest / Mareike Garms ; Gutachter: Marius Mayer, Hubert Job ; Betreuer: Hubert Job." Greifswald : Universität Greifswald, 2021. http://d-nb.info/1234149192/34.
Full textFilous, Angela R. Ph D. "The Role of NG2+ Cells in Regeneration Failure After Spinal Cord Injury." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396605992.
Full textBortolami, Giovanni. "Impact des agents pathogènes sur le bilan hydrique et carboné de la vigne : conséquences pour le dépérissement de la vigne." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0114.
Full textPerennial plant dieback is an increasing and complex phenomenon. Perennial plants experience many interacting stressing events leading to final plant mortality. These interactions, and how they may change regarding climatic conditions and plant physiological status, are key in understanding the dieback process. Although dieback events are increasing worldwide, the knowledge on the dieback mechanisms are scarce, given the many technical challenges in studying complex interactions. In this thesis, we studied the interaction between two stresses frequently experienced by grapevines, one of the most important perennial crops: drought and esca (a vascular disease). Esca is a disease in which there are many competing hypotheses regarding its pathogenesis. One of the main hypothesis is that leaf symptoms and plant death are caused by hydraulic failure in xylem vessels. For this reason, drought is thought to contribute synergistically with esca to grapevine dieback. In this context, this thesis has primarily explored the hydraulic failure hypothesis during esca pathogenesis. We found that during leaf symptom expression both leaves and stems suffer from hydraulic failure causing (on average) 69% loss of hydraulic conductance in midribs, 55% in petioles, and 30% in stems. Differing from classical air embolism during drought, we observed that hydraulic failure during esca was caused by the presence of plant-derived vascular occlusions (i.e. tyloses and gels) produced at a distance from the pathogen niche in the trunk. After this discovering, we explored the interaction between esca and drought, subjecting naturally infected plants to drought. We found that drought totally inhibits esca leaf symptoms, as none of the plants under water deficit (at ΨPD ≈ -1MPa for three months) expressed leaf symptoms in two consecutive seasons. At the same time, in order to understand the interaction between esca and drought, we recorded the whole-plant water relations and carbon economy of grapevine under both stresses. We highlight the distinct physiology behind these two stresses, indicating that esca and drought present different underlying mechanisms, and induce different plant responses and physiological consequences. Esca (and subsequent stomatal conductance decline) does not result from decreases in water potential, and generates different gas exchange and non-structural carbohydrate seasonal dynamics compared to drought. Finally, we observed that esca affected the recorded plant physiology only seasonally, and not over the long-term. This thesis highlights the importance in finding the physiological thresholds triggering the different interactions during plant dieback. Together, the results open new scientific and agronomical perspectives on plant-pathogen-environment interactions and vineyard sustainability
Semizer, Cuming Devrim [Verfasser], Reiner [Akademischer Betreuer] Finkeldey, Oliver [Gutachter] Gailing, and Kurt [Gutachter] Weising. "Gene flow from planted common ash (Fraxinus excelsior L.) stands to old-growth forests – implications for conservation and use of genetic resources affected by ash dieback / Devrim Semizer Cuming ; Gutachter: Oliver Gailing, Kurt Weising ; Betreuer: Reiner Finkeldey." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1173975039/34.
Full textBjörkroth, Jennie. "Effekter av naturvårdsgallring på förekomsten av lunglav på ädellövträd." Thesis, Linköpings universitet, Biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120089.
Full textWoltjen, Christine D. "Responding to industry needs from the field to the greenhouse: Dieback and cankers of Gleditsia triacanthos var. inermis and characterization of an Ohio isolate of Melon necrotic spot virus and its vector, Olpidium bornovanus, collected from Cucumis sativ." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1276549930.
Full textGeorge, Amy Kathryn. "Eucalypt regeneration on the Lower Murray floodplain, South Australia." Connect to this title online, 2004. http://hdl.handle.net/2440/37706.
Full textThesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.
Ben, M'henni Yosra. "Gestion de la maladie de dépérissement du pommier : criblage in vitro et in planta des activités protectrices d’une collection de microorganismes contre les Pythiacées et caractérisation chimique du principal actif produit par l’isolat A. westerdijkiae A7 Biocontrol and growth promotion potential of combined application of Trichoderma simmonsii and Aspergillus westerdijkiae in Apple root stock dieback." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS127.
Full textApple dieback is a telluric disease caused by several Pythiaceae species. It is responsible for serious damage and loss of trees in many orchards in Tunisia. As the chemical control of this disease poses eco-toxicological problems and the prophylactic means have limited effectiveness, other means of fight are actively sought. The objective of this thesis was to identify a new biological control agent against oomycetes responsible for this disease from a collection of Tunisian fungal and bacterial isolates as an alternative to chemical control. The fungal isolates studied belonged to the genera Trichoderma, Aspergillus and Penicillium spp., The bacterial isolates to the genus Bacillus spp. clade subtilis. Fungal isolates strongly inhibited the growth of Pythiaceae in vitro (> 40%) compared to bacterial isolates; in particular, the culture filtrates of isolates A. westerdijkiae A7 and T. simmonsii A2. The evaluation of the preventive and curative activity against Pythiaceae on apple rootstocks of these two fungal isolates and of the Bacillus B2 strain showed that T. simmonsii A2 was the most effective when applied preventively. Likewise, the combination of the Bacillus B2 strain and the A. westerdijkiae A7 isolate induced good protection against Pythiaceae as a preventive measure. The combination of the T. simmonsii A2 and A. westerdijkiae A7 isolates resulted in better protection in curative therapy, while the combination of the three isolates together greatly reduced the protective activity. Our study reveals the potential of Tunisian isolates, alone or in combination, as biological control agents against apple dieback as well as an additional beneficial effect on plant growth observed at the level of the roots and the length of the stems. Thus, we have selected the best candidates acting by antibiosis for the identification of the main active agents responsible for anti-oomycete activity. The A. westerdijkiae A7 isolate was retained with 100% inhibition of mycelial growth of the Pythiaceae isolates tested. Several successive purification steps of the culture filtrate made it possible to identify penicillic acid (3-mehoxy-5-methyl-4-oxo-2,5-hexadienoic acid) as the main molecule responsible for inhibiting growth mycelia of the Pythiaceae tested. Since penicillic acid has toxic properties for human and animal health, isolate A. westerdijkiae A7 cannot be used as BCA since it produces this mycotoxin despite our promising results in planta. All of this work shows the anti-oomycete potential of microorganisms in vitro, which may differ from the protective activity against Pythiaceae in planta. They also reveal the need to characterize the active molecule for the toxicity studies necessary for the development of a biocontrol product
Salowi, Asmah. "Towards biological control of Pistachio dieback." Thesis, 2010. http://hdl.handle.net/2440/63478.
Full textThesis (M.Ag.Sc.) -- University of Adelaide, School of Agriculture, Food and Wine, 2010.
Chakraborty, Tanmoy. "Multi-scale assessment of drought-induced forest dieback." Master's thesis, 2020. http://hdl.handle.net/10362/94403.
Full textDrought has been intensified over the years and will continue to worsen due to climate change. Existing works have focused their attention on crops rather than forests. Adverse effects are felt by all flora and fauna but the impact of the recent droughts on forest ecosystems is still unknown. Greater root depth allows them to withstand the immediate impacts of drought in contrast to crops and other vegetation. This study aims to see not only the interaction between drought and forest vitality from a multi-scale and temporal viewpoint while also to detect the impact of the recent 2018/19 drought on forest vitality based on remote sensing data. The data from the German Drought Monitor was used for the area-wide estimation of drought in Germany. Vegetative indices like NDVI collected from MODIS and Sentinel 2A were used to study the interactions between drought and forest vitality. Data for both have been acquired for the years 2000-2019. A long-standing time series data was decomposed and seasonally adjusted for better cross-correlation between the variables. The cross-correlation was verified by using breakpoints estimation by dividing the data into historically observed and test data. The coniferous-dominated black forest was used as a study area for a more in-depth analysis. Results showed that forest vitality was lowest one month after a severe drought, indicated by the highest decline in NDVI for all the forest types. This was verified using high resolution Sentinel images and the highest change does correspond to the month of January 2019. There was change in NDVI of over -0.5 for 80.63% of the entire study area. The change for each forest type was 81.74%, 54.42%, 84.14% for coniferous, broadleaved and mixed forests respectively. Two decades of NDVI and Soil Moisture Index (SMI) data along with Sentinel images for better area calculation because of higher resolution make this a highly effective approach to assess the impacts of drought on forest dieback. The methodology and data can be applied across the study area and with suitable drought indices can be used to assess the drought induced forest dieback across the globe. However, in-situ analysis with ecological considerations at the individual level could further the validity of the cross-correlations among forest types and drought. Reproducibility self-assessment (https://osf.io/j97zp/): 3, 2, 3, 1, 3 (input data, pre-processing, methods, computational environment, results).