Tesi sul tema "Roots (Botany) Diseases and pests"
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Babur, John Leland. "Shoot Structure of Boschniakia hookeri Walpers (Orobanchaceae)". PDXScholar, 1995. https://pdxscholar.library.pdx.edu/open_access_etds/4931.
Testo completoBizabani, Christine. "The diversity of root fungi associated with Erica species occurring in the Albany Centre of Endemism". Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018575.
Testo completoKasiamdari, Rina Sri. "Interactions between arbuscular mycorrhizal fungi and other root-infecting fungi". Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phk1887.pdf.
Testo completoTimm, Alicia (Alicia Eva). "Genetic diversity of root-infesting woolly apple aphid Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) populations in the Western Cape". Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53436.
Testo completoENGLISH ABSTRACT: Characterizing the genetic structure of a pest population can provide an understanding of the factors influencing its evolution and assist in its ultimate control. The aim of the present study was to characterize the genetic structure of woolly apple aphid Eriosoma lanigerum (Hausmann) populations in the Western Cape Province in South Africa. Since this economically important apple pest has not previously been characterized at molecular level, it was necessary to evaluate methods for determining the genetic structure of E. lanigerum populations. Two different molecular techniques were evaluated viz. random amplification of polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). This study represents the first application of the latter technique to members of the Aphididae. Aphids were sampled from four regions in the Western Cape in South Africa viz. Elgin, Ceres, Vyeboom and Villiersdorp. A spatially nested sampling design was used to establish the distribution of the genetic variance of aphids. A total of 192 individuals from 13 farms were analysed. Ten RAPD primers were chosen for analysis from an initial assay of 25 after fragment reproducibility had been confirmed. For AFLP analysis three different rare-cutting restriction enzymes were evaluated for AFLP analysis, viz. EcoRI, SseI and MluI. The latter yielded the best results in combination with the frequent-cutting enzyme MseI. Twenty-five AFLP selective primer pairs were evaluated, out of which five were chosen for analysis of the total population. Two hundred and fifty AFLP fragments and 47 RAPD fragments were scored for analysis. Both analyses indicated that a low level of genetic variation was apparent in E. lanigerum populations and that no differentiation resulted from geographic isolation. From RAPD analyses it was deduced that all variation could be attributed to differences between individuals. AFLP analysis indicated that, whereas genetic differences in E. lanigerum populations between orchards were negligible, a significant portion of genetic variation could be attributed to differences between farms and individuals within farms. Therefore, AFLP analysis allowed for finer discrimination of the genetic structure of E. lanigerum populations than RAPD analysis and is recommended for studies of other aphid species. The fact that most of the genetic variation present in E. lanigerum populations could be found on small spatial scales indicated that sampling individuals over a wide geographic area was an ineffective way of detecting the genetic diversity present in E. lanigerum populations. The low level of variation in populations is most likely due to the exclusive occurrence of parthenogenetic reproduction, founder effects (including distribution of infested plant material from a limited source) and selective factors such as the use of resistant rootstocks or pesticides. Furthermore, the low level of variation found indicated that the possibility of controlling E. lanigerum in the Western Cape using host plant resistance is favourable. Thus, plant breeders developing resistance to E. lanigerum can expect plant entries to be exposed to most of the genetic diversity present in Western Cape populations, regardless of location.
AFRIKAANSE OPSOMMING: Die bepaling van die genetiese struktuur van 'n landboukundige plaagpopulasie kan lei tot begrip van die faktore wat die populasie beïnvloed en kan uiteindelike beheer vergemaklik. Die doel van die huidige studie was om die genetiese struktuur van die appelbloedluis Eriosoma lanigerum (Hausmann) in die Wes-Kaap Provinsie van Suid-Afrika te bepaal. Aangesien hierdie belangrike appelplaag nie van tevore op molekulêre vlak bestudeer is nie, was dit nodig om metodes vir die bepaling van die genetiese struktuur van E. lanigerum populasies te evalueer. Twee molekulêre tegnieke is geëvalueer, nl. lukraak geamplifiseerde polimorfiese ONS (RAPD) en geamplifiseerde fragment-lengte polimorfismes (AFLP). Hierdie studie is die eerste om laasgenoemde tegniek te gebruik om lede van die Aphididae te bestudeer. Plantluise is verkry van vier verskillende gebiede in die Wes-Kaap Provinsie van Suid-Afrika nl. Elgin, Ceres, Vyeboom en Villiersdorp. 'n Hierargiese sisteem is gebruik om die verspreiding van die genetiese variasie van plantluise te bepaal. In totaal is 192 individue van 13 plase geanaliseer. Tien RAPD inleiers is gekies uit 'n analise van 25 verskillende inleiers nadat fragment reproduseerbaarheid bevestig is. Drie verskillende restriksie ensieme is geëvalueer vir AFLP analise nl. EcoRI, SseI en Mlul. Die beste resultate is verkry toe MluI saam met MseI gebruik is. Vyf-en-twintig AFLP selektiewe inleier pare is geëvalueer waarvan vyf gekies is vir analise van die totale populasie. Twee-honderd-en-vyftig AFLP fragmente en 47 RAPD fragmente is gedokumenteer vir analise. Beide RAPD en AFLP analises het getoon dat daar 'n lae vlak van genetiese variasie in E. lanigerum populasies is en dat geen differensiasie as gevolg van geografiese isolasie ontstaan het nie. Uit RAPD analise is daar afgelei dat al die variasie toegeskryf kon word aan verskille tussen individue. AFLP het aangetoon dat alhoewel verskille in E. lanigerum populasies tussen boorde laag was, kon 'n hoë persentasie van die variasie toegeskryf word aan verskille tussen plase en individue binne plase. AFLP analise het meer insig in die genetiese struktuur van E. lanigerum populasies verskaf, en word dus aanbeveel vir studies van ander plantluise. Omdat meeste van die genetiese variasie oor klein geografiese afstande verkry word, is steekproefueming oor groot gebiede 'n ondoeltreffende manier om die genetiese variasie binne 'n monster te meet. Die lae vlak van genetiese variasie is waarskynlik te wyte aan partenogenetiese vermeerdering, stigter gevolge (insluitend verspreiding van geïnfesteerde plantmateriaal vanaf 'n beperkte bron), sowel as selektiewe faktore soos die gebruik van bestande onderstokke en insekdoders. Verder dui die lae vlak van variasie aan dat die moontlikheid vir beheer deur gasheerplantbestandheid goed is in die Wes-Kaap. Planttelers kan verseker wees dat hulle plante blootgestel sal wees aan meeste van die genetiese variasie in die Wes-Kaap appelbloedluis populasies ongeag hulle ligging.
Balasubramaniam, Rengasamy. "The effects of foliar diseases and irrigation on root development, yield and yield components of wheat (Triticum aestivum L.)". Lincoln College, University of Canterbury, 1985. http://hdl.handle.net/10182/1514.
Testo completoTomimatsu, Gail Susan. "Quantitative Investigations of Infection and Colonization of Peanut Roots by Cylindrocladium crotalariae". Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/76172.
Testo completoPh. D.
Van, Coller Gerhardus J. (Gerhardus Johannes). "An investigation of soilborne fungi associated with roots and crowns of nursery grapevines". Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49844.
Testo completoENGLISH ABSTRACT: Soilborne diseases of grapevines represent a complex problem with limited information available, both locally and internationally. Previous research in South Africa indicated that Phytophthora and Pythium spp. were the most widespread and devastating pathogens in grapevine nurseries and vineyards in the Western Cape province. The local grapevine industry is currently expanding; new cultivars, methods and agricultural chemicals are being used which can affect soilborne pathogens. It has therefore become necessary to reassess the status of soilborne pathogens in nurseries, since information in this regard is crucial for the development of disease management practices for the expanding local grapevine industry. Soilborne fungal genera associated with roots and crowns of declining nursery grapevines were assessed in surveys conducted at three different grapevine nurseries in the Western Cape province. Cylindrocarpon, Fusarium, Pythium, and Rhizoctonia spp. were consistently isolated from roots and crowns of declining nursery grapevines. Cylindrocladiella spp. and Phytophthora cinnamomi were infrequently isolated from diseased roots, crowns and soil whereas Pythium spp. were abundant in most of the soils. Results suggest that the status of soilborne fungal pathogens in grapevine nurseries in the Western Cape province has changed over the last 30 years. The DNA phylogeny and pathogenicity of the isolates of Cylindrocladiella were determined. Four species of Cylindrocladiella occur on grapevines in South Africa, namely C. lageniformis, C. parva, C. peruviana, as well as a new species, described in this study as C. viticola, which forms part of the C. infestans species complex. Pathogenicity trials were inconclusive. Ten Fusarium spp. were isolated from roots and crowns of declining nursery grapevines, namely F. acuminatum, F. anthophilum, F. chlamydosporum, F. equiseti, F. nygamai, F. oxysporum, F. proliferatum, F. scirpi, F. semitectum and F. solani. The dominant species was F. oxysporum, followed by F. proliferatum and F. solani. In pathogenicity trials F. oxysporum and F. solani significantly reduced root volume, root dry mass, length of new shoots, stem diameter and number of leaves, but increased the percentage of chlorotic leaves and root rot severity. Fusarium proliferatum also caused a significant reduction in new shoot growth, number of leaves and increased root rot severity compared to the controls. Fusarium so/ani seems to be more virulent than F. oxysporum, followed by F. pro/iferatum. This is the first report of F. oxysporum, F. pro/iferatum and F. so/ani as pathogens of grapevines in South Africa, and the first report of F. proliferatum as a pathogen of grapevines in the world. Phytophthora cinnamomi was isolated at low frequencies from declined grapevines, although present in the rhizosphere soil. It is possible that the extensive use of downy mildew chemicals in grapevine nurseries may protect grapevines from infection by P. cinnamomi. The effect of chemicals used to combat downy mildew on Phytophthora root rot of nursery grapevines was evaluated in a glasshouse. There was very little discernable effect of the chemicals tested relative to the control plants for the parameters measured and it was concluded that the inoculation technique needed refinement. However, plants treated with phosphorous acid tended to be taller and have more leaves, greater stem diameter and root volume than controls or plants treated with the other chemicals. The data obtained in this study are not conclusive, but indicated certain trends that more glasshouse trials and field trials would resolve. Results presented in this thesis indicate that a major shift has occurred in the status of soilborne fungi associated with roots and crowns of grapevines in nurseries in the Western Cape since the 1970s when Phytophthora and Pythium were predominant. The prevalence and role of soilborne fungi need to be determined so that new appropriate disease management strategies can be developed to limit losses in grapevine nurseries and ensure the sustainable production of healthy plants for the grapevine industry.
AFRIKAANSE OPSOMMING: 'N ONDERSOEK NA GRONDGEDRAAGDE SWAMME GEASSOSIEER MET WORTELS EN KRONE VAN WINGERD IN KWEKERYE Grondgedraagde siektes van wingerd is 'n komplekse probleem waaroor min inligting, beide plaaslik en internasionaal, beskikbaar is. Vorige navorsing in Suid-Afrika het aangedui dat swamme van die genera Phytophthora en Pythium die mees algemene en vernietigende grondgedraagde patogene in kwekerye en wingerde in die Wes-Kaap provinsie is. Die plaaslike wingerdbedryf brei huidiglik uit; nuwe kultivars, metodes en landbouchemikalieë word gebruik wat 'n invloed kan hê op grondgedraagde patogene. Gevolglik het dit noodsaaklik geword om die status van grondgedraagde patogene in wingerdkwekerye weer te bepaal, aangesien inligting in hierdie verband noodsaaklik is vir die ontwikkeling van siekte bestuurspraktyke vir die ontwikkelende plaaslike wingerdbedryf. Grondgedraagde swamgenera geassosieer met wortels en krone van terugsterwende wingerd in kwekerye is bepaal in opnames wat by drie verskillende wingerdkwekerye in die Wes-Kaap provinsie uitgevoer is. Cylindrocarpon, Fusarium, Pythium, en Rhizoctonia spp. is konstant vanuit wortels en krone van terugsterwende wingerdplante in kwekery geïsoleer, Cylindrocladiella spp. en Phytophthora cinnamomi is ongereeld vanuit siek wortels, krone en grond geïsoleer, terwyl Pythium spp. algemeen in meeste gronde voorgekom het. Resultate dui daarop dat die status van grondgedraagde swampatogene in wingerdkwekerye in die Wes- Kaap provinsie oor die laaste 30 jaar verander het. Die DNA filogenie en patogenisiteit van die isolate van Cylindrocladiella is bepaal. Vier spesies van Cylindrocladiella kom voor op wingerd in Suid-Afrika, naamlik C. lageniformis, C. parva, C. peruviana, sowel as 'n nuwe spesie, wat in hierdie studie as C. viticola aangedui is en wat deel is van die C. infestans spesie kompleks. Patogenisiteits proewe was onvoldoende om die patogeniese status van die swam me te bepaal. Tien Fusarium spp. is vanuit wortels en krone van terugsterwende wingerdplante in kwekery geïsoleer, naamlik F. acuminatum, F. anthophilum, F. chlamydosporum, F. equiseti, F. nygamai, F. oxysporum, F. proliferatum, F. scirpi, F. semitectum en F. solani. Die dominante spesies was F. oxysporum, gevolg deur F. proliferatum en F. solani. In pathogenisteitsproewe het F. oxysporum en F. solani gelei tot 'n betekenisvolle laer wortelvolume, droë massa van wortels, lengte en droë massa van nuwe groei en aantal blare, maar het die persentasie chlorotiese blare en graad van wortelvrot verhoog. Fusarium proliferatum het ook gelei tot 'n betekenisvolle afname in lengte en massa van nuwe groei, aantal blare en 'n verhoogde graad van wortelvrot in vergelyking met die kontrole behandelings. Dit wil voorkom asof Fusarium solani meer virulent is as F. oxysporum, gevolg deur F. proliferatum. Hierdie is die eerste aanmelding van F. oxysporum, F. proliferatum en F. solani as patogene van wingerd in Suid-Afrika, en die eerste aanmelding van F. proliferatum as 'n patogeen van wingerd in die wêreld. Phytophthora cinnamomi is konstant teen lae frekwensies vanuit terugsterwende wingerd in kwekerye geïsoleer, alhoewel dit in risosfeer gronde teenwoordig was. Dit is moontlik dat die ekstensiewe gebruik van chemikalieë teen donsskimmel in wingerdkwekerye die wingerdplante kan beskerm teen infeksie deur P. cinnamomi. Die effek van chemikalieë wat gebruik word teen donsskimmel op Phytophthora wortelverrotting van wingerd in kwekerye, is 'n glashuis geëvalueer. Die chemikalieë wat gestoets is, het vir die gemete parameters, tot baie min onderskeibare effek gelei relatief tot die kontrole plante, en daar is afgelei dat die inokulasie tegniek verbetering benodig. Plante wat met fosforiensuur behandel is, het egter geneig om langer te wees met meer blare, 'n groter stamdeursnee en wortelvolume as kontrole plante of plante behandel met ander chemikalieë. Data verkry vanuit die hierdie studie was onvoldoende, maar sekere neigings is aangedui wat deur verdere glashuis- en veldproewe verklaar sal word. Resultate wat in hierdie tesis weergegee is, het aangedui dat 'n algehele verskuiwing in die status van grondgedraagde swamme geassosieer met wortels en krone van wingerd in kwekerye vanaf die 1970s, toe Phytophthora en Pythium die dominante genera was, plaasgevind het. Die voorkoms en rol van grondgedraagde swamme moet bepaal word, sodat nuwe voldoende siektebestuurspraktyke ontwikkel kan word om verliese in wingerdkwekerye te beperk en sodoende die volhoubare produksie van gesonde plante vir die wingerdbedryf te verseker.
Aylward, Janneke. "Diversity and dispersal of the ophiostomatoid fungus, Knoxdaviesia proteae, within Protea repens infructescences". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86324.
Testo completoENGLISH ABSTRACT: Two genera of ophiostomatoid fungi occur in the seed-bearing structures of serotinous Protea species in the Cape Floristic Region. These fungi are dispersed by arthropods, including mites and beetles that visit the Protea host plants. Although the vectors of Proteaassociated ophiostomatoid fungi are known, their dispersal patterns remain unknown – especially the manner in which recently burnt fynbos vegetation is recolonized. Additionally, their reproduction strategy has not previously been investigated. The focus of this study was, therefore, to determine the extent of within- and between-plant dispersal of Proteaassociated ophiostomatoid fungi at the population level and to investigate their reproductive strategy. One Protea-associated ophiostomatoid fungus, Knoxdaviesia proteae, is found exclusively in the fruiting structures of P. repens and was the focus of this study. In order to interrogate natural populations of this fungus, 12 polymorphic microsatellite markers specific to K. proteae were developed with an ISSR-PCR enrichment strategy and pyrosequencing. These markers were amplified in two distantly separated populations of K. proteae. The genetic and genotypic diversities of both populations were exceptionally high and neither showed significant population differentiation. The lack of population structure in both populations implies that K. proteae individuals within a P. repens stand are in panmixia. As one of the sampling sites had burnt recently, the process whereby young fynbos is recolonized could be investigated. Compared to the adjacent, unburnt area, K. proteae individuals in the burnt area of this population had significantly less private alleles, suggestive of a young population that had experienced a genetic bottleneck. Knoxdaviesia proteae individuals that did not originate from the adjacent unburnt area were encountered within the burnt site and, additionally, isolation-by-distance could not be detected. The parsimony-based haplotype networks and the tests for linkage disequilibrium indicated that recombination is taking place within as well as between the two distantly separated populations. The observed panmixia in P. repens stands, widespread recolonization and the high genetic similarity and number of migrants between the two populations emphasizes long-distance dispersal and therefore the role of beetles in the movement of K. proteae. This cohesive genetic structure and connection across large distances is likely a result of multiple migration events facilitated by beetles carrying numerous phoretic mites.
AFRIKAANSE OPSOMMING: Twee genera ophiostomatoid swamme kom in die saad-draende strukture van bloeiende Protea spesies in the Kaapse Floristiese Streek voor. Hierdie Protea-verwante ophiostomatoid swamme word gekenmerk deur hul assosiasie met geleedpotige vektore – spesifiek die myt en kewer besoekers van die Protea gasheer plante. Alhoewel die geleedpotige vektore van Protea-verwante ophiostomatoid swamme bekend is, is die wyse waarop hierdie swamme versprei onbekend; veral die manier waarop onlangse gebrande fynbos geherkoloniseer word. Verder is die voortplantings-strategie van hierdie swamme nog nie voorheen ondersoek nie. Die fokus van hierdie studie was dus om die omvang van binne- en tussen-plant verspreiding van Protea-verwante ophiostomatoid swamme te bepaal op die populasie vlak en om hul voorplantings-strategie te ondersoek. Een Protea-verwante ophiostomatoid swam, Knoxdaviesia proteae, word uitsluitlik in die vrugdraende strukture van P. repens aangetref en was die fokus van hierdie studie. Om natuurlike populasies van hierdie swam te ondersoek is 12 mikrosatelliet-merkers spesifiek vir K. proteae ontwerp deur ‘n ISSR-PCR strategie en “pyro”-basisvolgorde bepaling te gebruik. Hierdie merkers is geamplifiseer in twee K. proteae populasies wat ver van mekaar geskei is. Die genetiese en genotipiese diversiteit van beide populasies was uitsonderlik hoog en nie een het beduidende populasie-differensiasie getoon nie. Die gebrek aan populasie struktuur in beide populasies veronderstel dat K. proteae individue binne ‘n P. repens stand in panmiksia is. Aangesien een van die steekproef terreine onlangs gebrand het, kon die herkolonisasie proses van jong fynbos ondersoek word. In vergelyking met die aangrensende, ongebrande area, het K. proteae individue in die gebrande area beduidend minder private allele gehad. Dit dui op ‘n jong populasie wat ‘n genetiese bottelnek beleef het. Knoxdaviesia proteae individue wat nie van die aangrensende, ongebrande area afkomstig is nie is ook binne die gebrande terrein aangetref. Verder is afsondering-deur-afstand nie aangetref nie. Die parsimonie-gebaseerde haplotiepe-netwerke en die toetse vir koppeling-onewewigtigheid het aangedui dat rekombinasie binne sowel as tussen die twee populasies plaasvind. Die panmiksia wat waargeneem is in P. repens populasies, wydverspreide herkolonisasie en die hoë genetiese ooreenkoms en hoeveelheid immigrante tussen die twee populasies beklemtoon lang afstand verspreiding en dus die rol van kewers in die beweging van K. proteae. Hierdie samehangende genetiese struktuur en die verband oor groot afstande is waarskynlik ‘n gevolg van verskeie migrasies gefasiliteer deur kewers wat talle foretiese myte dra.
DeYoung, Robyn Merrilee. "Gall formation by Erwinia species on Douglas-fir". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28980.
Testo completoLand and Food Systems, Faculty of
Graduate
Han, Liwen 1964. "Assessment of common scab effects on the development of potato root systems using computed tomography scanning data". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101849.
Testo completoDyer, Sonya. "The role of colonisation of soil and wheat roots by Trichoderma koningii in biological control of Gaeumannomyces graminis var. tritici". Title page, table of contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phd9966.pdf.
Testo completoMustafa, Bakray Nur Aqilah Binti. "Structure of root associated and soil fungal and bacterial communities in Southeast Asia tropical forest". Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239153.
Testo completoMusvuugwa, Tendai. "Biodiversity and ecology of ophiostomatoid fungi associated with trees in the Cape floristic region of South Africa". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86421.
Testo completoENGLISH ABSTRACT: Very little is known about the diversity of fungi associated with Afromontane forests of the Cape Floristic Region (CFR) of South Africa. The ophiostomatoid fungi include many species, some known as pathogens in the CFR, while others are well-known saprophytes important in wood degradation. This study focused on the biodiversity and ecology of tree-associated ophiostomatoid fungi (Ophiostomatales) in the CFR. In addition to this, mites and subcortical beetles associated with the CFR trees were collected, regardless of whether they were associated with ophiostomatoid fungi or not. A relatively high diversity of ophiostomatoid fungi were collected from native trees, ten of which were newly described here. Three further fungal species, two of which are probably new to science, were also collected from exotic Pinus species growing in these forests. Four Ophiostomatales species (including three newly described species) were associated with subcortical beetles on Rapanea melanophloeos and Olea capensis ssp. macrocarpa. These were Sporothrix pallida, Sporothrix aemuluphilus, Raffaelea scabbardiae and Raffaelea rapaneae, associated with the beetles Lanurgus sp. 1, Ctonoxylon sp. 1, Xyleborinus aemuluphilus and a Platypodinae species. This represents a first study to explore the associations between subcortical beetles and ophiostomatoid fungi on native trees in the CFR. In addition to fungi associated with subcortical beetles, several members of the Ophiostomatales associated with wounds on Rapanea melanophloes trees were also collected. These included Ophiostoma stenoceras, Sporothrix reniformis, S. rapaneae, S. lunateae and S. noisomeae. All but O. stenoceras were new to science, and were formally described here. All of these wound-associated species from R. melanophloeos belong to the Sporothrix schenckii – O. stenoceras complex, except for S. noisomeae that was provisionally placed in the S. lignivora complex. Besides fungal taxa collected from wounds on Rapanea melanophloeos, other fungi were also collected from wounds on other host trees species. Three more previously undescribed ophiostomatoid fungal species were collected from this niche. They included Sporothix capensis collected from O. capensis ssp. macrocarpa, Graphilbum roseus collected from many different, unrelated host trees and Graphium ilexiense (Microascales), isolated from wounds on Ilex mitis. The latter represented the first isolation of an ophiostomatoid fungus from this host tree species. Two possibly new fungal species (Sporothrix sp. 1, Ceratocystiopsis sp. 1) and Ophiostoma ips, associated with three bark beetles (Orthotomicus erosus, Hylurgus ligniperda and Hylastes angustatus), were collected from Pinus. Several fungal species were collected from both native trees and non-native trees. These included Sporothrix fusiforme from Brabejum stellatifolium and Acacia mearnsii, O. quercus and O. pluriannulatum-like fungus from several native trees and from A. mearnsii. This suggests a possibility for host shifting of some of these fungi between native and non-native hosts or even between different native hosts. Eight non-ophiostomatoid fungi associated subcortical beetles taxa were found also to infest native trees in the Afromontane forests and in total more than 4500 beetle individuals were collected. Some species of ophiostomatoid fungi collected in this study were found to be associated with other arthropods such as mites. Four phoretic mites species associated with ophiostomatoid fungi (Dendrolaelaps quadrisetus, Histiogaster sp. 3, Elattoma sp. 1 & 2) were collected. In addition, sixteen species of tree wound-associated mites were collected from 12 native trees. Of these, nine were associated with several ophiostomatoid fungi (Graphilbum roseus, O. pluriannulatum-like, O. quercus) that were isolated from several different host trees. This suggests that they may aid in the transport of these fungi from one host species to another. The possible consequences of transfers of Ophiostomatales species between hosts were tested using pathogenicity tests, which highlighted that some fungi are pathogenic on several different trees. Transfers seemed most likely in fungal species isolated from wounds, especially those associated with mites, because the mites may aid in the vectoring of these. When phoretic mites were tested for their specificity to their vector beetles, they proved to be highly specific. Although some of the fungi associated with these mites and their sub-cortical beetles were also pathogenic, it is less likely for these fungi to be transferred to other host tree species due to the high specificity of their arthropod associates. This study represents one of a few studies that focused on ophiostomatoid fungi, subcortical beetles and mites associated with trees in the Afromontane forests of South Africa. Although we collected a high diversity of Ophiostomatales members, many more still await discovery. It is recommended that future studies focus on the complex inter-organismal interactions in many of the systems uncovered in this study.
AFRIKAANSE OPSOMMING: Baie min is bekend oor die diversiteit van fungi wat met die Afromontane woude van die Kaapse Floristiese Streek (KFS) van Suid Afrika geassosieer is. Die ophiostomatoïde fungi sluit baie spesies in, sommiges bekend as patogene in die KFS, terwyl ander bekende en belangrike saprofiete in houtdegradasie is. Hierdie studie het op die biodiversiteit en ekologie van die boom-geassosieerde ophiostomatoïde fungi (Ophiostomatales) in die KFS gefokus. Daarbenewens is myte en subkortikale kewers wat met die KFS bome geassosieer word ook versamel, ongeag of hulle geassosieerd was met ophiostomatoïde fungi of nie. „n Relatief hoë diversiteit van ophiostomatoïde fungi is van inheemse bome versamel, tien waarvan hier nuut beskryf is. Drie verdere fungi spesies, twee waarvan ook waarskynlik nuut is tot die wetenskap, is ook vanaf Pinus spesies versamel wat in hierdie woude gegroei het. Vier Ophiostomatales spesies (insluitend drie nuut beskryfde spesies) wat met subkortikale kewers op Rapanea melanophloeos en Olea capensis L. ssp. macrocarpa geassosieer is, is ook versamel. Hulle was Sporothrix pallida, Sporothrix aemuluphilus, Raffaelea scabbardiae en Raffaelea rapaneae, geassosieer met die kewers Lanurgus sp. 1, Ctonoxylon sp. 1, Xyleborinus aemuluphilus en „n Platypodinae spesie. Hierdie verteenwoordig die eerste studie wat die assosiasies tussen subkortikale kewers en ophiostomatoïde fungi op inheemse bome in die KFS ondersoek. Addisioneel tot fungi geassosieer met die subkortikale kewers, is verskeie lede van die Ophiostomatales vanaf wonde op Rapanea melanophloes bome versamel. Hulle sluit in Ophiostoma stenoceras, Sporothrix reniformis, S. rapaneae, S. lunateae en S. noisomeae. Almal behalwe O. stenoceras was nuut tot die wetenskap, en is hier formeel beskryf. Al hierdie wond-geassosieerde spesies vanaf R. melanophloeos behoort aan die Sporothrix schenckii – O. stenoceras kompleks, behalwe vir S. noisomeae wat voorlopig in die S. lignivora kompleks geplaas is. Benewens fungi taxa wat van die wonde op Rapanea melanophloes versamel is, is ander fungi ook vanaf die wonde op ander gasheer boom spesies versamel. Drie verdere ophiostomatoïde fungus spesies is in hierdie nis versamel. Hulle sluit in Sporothix capensis wat vanaf O. capensis ssp. macrocarpa versamel is, Graphilbum roseus wat vanaf baie verskillende, onverwante gasheer bome versamel is en Graphium ilexiense (Microascales), wat vanaf wonde op Ilex mitis versamel is. Laasgenoemde verteenwoordig die eerste isolasie van „n ophiostomatoïde fungus vanaf hierdie gasheer boom spesie. Twee moontlik nuwe fungus spesies (Sporothrix sp. 1, Ceratocystiopsis sp. 1) en Ophiostoma ips, geassosieer met drie baskewers (Orthotomicus erosus, Hylurgus ligniperda en Hylastes angustatus) is vanaf Pinus versamel. Verskeie fungi spesies is van beide inheemse en nie-inheemse bome versamel. Hulle het Sporothrix fusiforme vanaf Brabejum stellatifolium en Acacia mearnsii, O. quercus en O. pluriannulatum-like fungus vanaf verskeie inheemse bome en vanaf A. mearnsii ingesluit. Dit suggereer die moontlikheid van gasheer-skuiwing van sommige van hierdie fungi tussen inheemse en uitheemse gashere of selfs tussen verskillende inheemse gashere. Agt nie- ophiostomatoïde geassosieerde subkortikale kewers was ook versamel en in totaal is meer as 4500 kewer indiwidue versamel. Sommige ophiostomatoïde fungus spesies wat in hierdie studie versamel is, was met ander geleedpotiges soos myte geassosieer. Vier foretiese myt spesies wat met ophiostomatoïde fungi geassosieer is (Dendrolaelaps quadrisetus, Histiogaster sp. 3, Elattoma sp. 1 & 2), is versamel. Nege addisioneële myt spesies was met verskeie ophiostomatoïde spesies vanaf verskeie boomspesies geassosieer (Graphilbum roseus, O. pluriannulatum-like, O. quercus). Dit suggereer dat myte die vervoer van hierdie fungi van een gasheer spesie na die ander mag bewerkstellig. Die moontlike gevolge van die oordrag van Ophiostomatales spesies tussen gashere is getoets deur patogeniteitstoetse. Dit het beklemtoon dat sommige fungi patogenies is op verskeie onverwante boomspesies. Oordraag van spesies is mees waarskynlik in fungi spesies wat vanaf wonde geisoleer is, veral dié wat met myte geassosieer is, want die myte mag hierdie fungi help vervoer. Toe foretiese myte getoets is vir hulle spesifisiteit tot hulle vektore, is hulle hoogs spesifiek bevind. Alhoewel sommige fungi wat met hierdie myte en hulle geassosieerde kewers geassosieer word wel patogenies is, is dit minder waarskylik dat hulle na ander gasheer bome sal verskuif as gevolg van die hoë spesifisiteit van hulle geleedpotige assosiate. Hierdie studie verteenwoordig een van net enkele studies gefokus op ophiostomatoïde fungi, subkortikale kewers en myte wat met bome van die Afromontane woude van Suid-Afrika geassosieer is. Alhoewel ons „n hoë diversiteit van Ophiotomatale lede versamel het, wag baie meer fungi spesies waarskynlik nog op ontdekking. Daar word voorgestel dat toekomstige studies fokus op die komplekse inter-organismiese interaksies in baie van die sisteme wat in hierdie studie blootgelê is.
Dunfield, Peter F. "Effects of a sugar-factory byproduct compost on root growth and mycorrhizal infection of sugarcane in Barbados". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60017.
Testo completoMachingambi, Netsai. "An investigation into the death of native Virgilia trees in the Cape Floristic Region of South Africa". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79902.
Testo completoENGLISH ABSTRACT: The Cape Floristic Region (CFR) of South Africa is well-recognised for exceptionally high plant species diversity and endemism. However, little attention has been bestowed on the pests and pathogens in this region, even though these may greatly influence plant distribution and evolution. In this study we identify various arthropods and fungi as pests and diseasecausing organisms of the ecologically and economically important CFR-endemic tree taxa of Virgilia. We isolated, identified and determined the pathogenicity of key fungal taxa from diseased Virgilia trees throughout the CFR. In addition we evaluated the role of possible pest arthropod taxa, including bark beetles, phoretic mites, larvae of a cerambycid beetle and larvae of the endemic Leto venus (ghost moth), in the death of Virgilia trees. Key fungal taxa were identified by comparisons of the internal transcribed spacer rDNA regions of the isolated taxa with those available on GenBank. Pathogenicity of the most commonly encountered fungal taxa was determined both in the field and under greenhouse conditions. Five different disease symptoms were observed on Virgilia trees throughout the CFR. At Table Mountain, Virgilia oroboides subsp. oroboides showed symptoms of: (1) several small cankers on stems, seemingly caused by a Fusarium acuminatum-like fungus, (2) a root rot disease caused by Armillaria mellea and (3) small bracket fungi on stems associated with Schizophyllum commune. Virgilia oroboides from the Harold Porter National Botanical Garden was diagnosed with a root disease consistently associated with an un-described Phomopsis species. Virgilia oroboides subsp. ferruginea and V. divaricata from Knysna and the Tsitsikamma area often showed symptoms of rapid wilting and death. The Virgilia stems were damaged by the tunnelling larvae of the ghost moth and those of an unidentified cerambycid beetle. Galleries and the surrounding wood tissues often housed the ophiostomatoid fungi Ceratocystis tsitsikammensis and Ophiostoma plurianulatum. These seem to originate from nitidulid beetles found feeding on gum exudate. Pathogenicity trials confirmed the virulence of the undescribed Phomopsis species, the F. acuminatum-like fungus, S. commune and C. tsitsikammensis to Virgilia. All four morpho-species of bark beetles found in this study, together with phoretic mites on two of the beetle morphospecies, were only collected from dead and dying Virgilia hosts and were classified as secondary pests. Both beetle taxa and mites commonly carried spores of various Geosmithia spp. These are not pathogenic to Virgilia trees, but may be an important food source for the bark beetles, as it dominated the fungal community in galleries. The phoretic mites were unable to feed on their Geosmithia associates, but have been observed to feed on dead bark beetle larvae within galleries. This suggests that the relationship of bark beetles, mites and their associated Geosmithia species in this system is complex and in need of further study. Our results show that natural populations of Virgilia play host to numerous destructive pathogens, some of which are non-native (e.g. A. mellea) and a cause for special concern. Additionally, the isolation of the undescribed Phomopsis species and A. mellea from botanical gardens, with A. mellea now spreading to natural areas, calls for stricter control over the movement of organic material from these areas.
AFRIKAANSE OPSOMMING: Die Kaapse Floristiese Streek (KFS) van Suid-Afrika is bekend vir buitengewoon hoë plantspesie-diversiteit en endemisme. Min aandag is egter tot dusver geskenk aan die peste en patogene in hierdie streek, al mag hulle plantverspreiding en evolusie dramaties beinvloed. In hierdie studie identifiseer ons verskeie geleedpotige diere en fungi as peste en organismes wat siektes veroorsaak in die ekologies en ekonomies belangrike, KFS-endemiese boom genus Virgilia. Ons het die sleutel fungi vanaf Virgilia oor die hele KFS geisoleer, geidentifiseer en hulle patogeniteit bepaal. Addisioneel het ons ook die rol van moontlike pes geleedpotiges, insluitende baskewers, cerambycid kewerlarwes en die endemiese Leto venus (spookmot) in die dood van Virgilia bome geevalueer. Sleutel fungi taksa is geidentifiseer deur die interne getranskribeerde spasieerder rDNS streke van die geisoleerde taksa met die wat op GenBank beskikbaar was te vergelyk. Patogenisiteit van die mees algemeen geisoleerde fungi taxa is beide in die veld en onder glashuis-toestande bepaal. Vyf verskillende siekte simptome is by Virgilia bome regdeur die KFS waargeneem. By Tafelberg het Virgilia oroboides subsp. oroboides simptome getoon van: (1) verskeie klein kankers op stamme, blykbaar veroorsaak deur ‘n Fusarium acuminatum-agtige fungus, (2) ‘n wortelvrot siekte veroorsaak deur Armillaria mellea en (3) klein rakswamme op stamme geassosieer met Schizophyllum commune. Virgilia oroboides in die Harold Porter Nationale Botaniese Tuin is gediagnoseer met ‘n wortelvrot siekte wat altyd met ‘n onbeskryfde Phomopsis spesie geassosieer is. Virgilia oroboides subsp. ferruginea and V. divaricata van Knysna en die Tsitsikamma area het dikwels simptome getoon van vinnige verwelking en dood. Die Virgilia stamme is deur die tonnelende larwes van die spookmot en dié van ‘n ongeidentifiseerde cerambycid kewer beskadig. Galerye en die omringende houtweefsel het dikwels die ophiostomatoid fungi Ceratocystis tsitsikammensis en Ophiostoma plurianulatum gehuisves. Dit lyk asof hierdie fungi van nitidulid kewers afkomstig is wat op die gomuitskeidings gevoed het. Patogeniteitsproewe het die kwaadaardigheid van die onbeskryfde Phomopsis spesie, die F. acuminatum-agtige fungus, S. commune en C. tsitsikammensis teenoor Virgilia bevestig. Al vier morfo-spesies baskewer wat in hierdie studie gevind is, sowel as die foretiese myte op twee van die kewer morfo-spesies, is slegs van dooie of sterwende Virgilia gashere versamel, en is as sekondêre peste geklassifiseer. Beide kewerspesies en myt taksa het algemeen spore van verskeie Geosmithia spesies (Geosmithia pallida, G. flava, G. microcorthyli, G. sp. 1 en G. sp. 2) gedra. Die Geosmithia spesies is nie patogenies teenoor Virgilia bome nie, maar mag ‘n belangrike voedselbron vir die baskewers wees, aangesien dit die fungus-gemeenskap in die galarye gedomineer het. Die foretiese myte was nie instaat om op Geosmithia-assosiate te voed nie, maar is waargeneem om op dooie baskewer larwes te voed binne die galerye. Dit stel voor dat die verhouding van die baskewers, myte en hulle geassosieerde Geosmithia spesies in die sisteem kompleks is, en verdere studie benodig. Ons resultate dui aan dat natuurlike populasies van Virgilia gashere is vir verskeie destruktiewe patogene, sommige waarvan nieinheems (bv. A. mellea) wat ‘n bron van groot kommer is. Verder noodsaak die isolasie van die Phomopsis spesie en A. mellea, wat beide wortelvrot siektes in botaniese tuine veroorsaak, strenger kontrole oor die verskuiwing van organiese materiaal uit hierdie areas, veral gegewe dat A. mellea reeds na natuurlike areas versprei het.
The Centre of Excellence In Tree Health Biotechnology for a bursary and funding the research conducted in this study
Van, Jaarsveld Alwyn Jacobus. "Plant parasitic organisms in the rizosphere of apple trees in the Western Cape, with special reference to woolly apple aphid". Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53551.
Testo completoENGLISH ABSTRACT: Various aspects of the biology and ecology of woolly apple aphid, Eriosoma lanigerum, were investigated, including initial galling damage caused by E. lanigerum to the roots of apple trees, the possible relationship between E. lanigerum and Xiphinema and Pratylenchus nematodes and the effectiveness of Biostart 2000® and Furfural® as possible control agents of E. lanigerum in the orchard. Preliminary root damage by first instar E. lanigerum feeding was characterized by the mechanical injury of endodermis and parenchyma tissues. Damage by second, third and fourth instar E. lanigerum was similar, but the symptoms were more pronounced. Damage caused by adults included a pronounced swelling at infected areas of the root. Cell walls hardened until the root was radially strengthened with sclerenchyma tissue and nonconducting xylem vessels while the cuticle expanded greatly through the growth of corklike cambium tissue. There was no direct relationship between the population dynamics of E. lanigerum and those of Xiphinema and Pratylenchus nematodes. The occurrence of E. lanigerum appeared to be seasonal while P. penetrans and Xiphinema numbers fluctuated erratically. Undamaged root nitrogen levels seemed to correspond with the normal root growth cycle. Nitrogen levels from galled roots were significantly lower than those of undamaged roots, probably due to E. lanigerum feeding. Soils rich in fine sand and clay sustained higher populations of E. lanigerum and Xiphinema than sandy soils. The number of E. lanigerum found in soil samples correlated well with the damage index allocated to the samples. The numbers of Xiphinema found in soil samples also correlated well with the damage index allocated to the samples according to suspected Xiphinema damage symptoms. Both Biostart 2000® and Furfural® were effective as control agents of woolly apple aphid. Furfural'Ï, a chemical waste product of the sugarcane industry, was however not as effective as Biostart 2000®, a product that includes an activator and three bacterial species, Bacillus laterosporus, B. chitinosporus and B. licheniformis. The bacteria in the Biostart 2000® treated pots could replicate themselves under suitable conditions while Furfural® dilutes with each watering. Biostart 2000® is also easier to prepare than Furfural® since the components of Biostart 2000® readily mix to form a paste easily thinned by water, whereas Furfural® is an oily substance that does not easily disperse in water. Root damage was initiated soon after E. lanigerum started feeding, however there was no apparent relationship between E. lanigerum and the nematode species. The most promising, environmentally friendly control measure was Biostart 2000®.
AFRIKAANSE OPSOMMING: Verskeie aspekte van biologie en die ekologie van die appel bloedluis, Eriosoma lanigerum, was ondersoek insluitende aanvanklike galvorming veroorsaak deur E. lanigerum op wortels van appelbome, die moontlike verwantskap tussen E. lanigerum en Xiphinema en Pratylenchus nematodes en die effektiwiteit van Biostart 2000® en Furfural® as moontlike beheeragente van E. lanigerum in die boord. Aanvanklike wortelskade deur eerste ins tar E. lanigerum voeding was gekenmerk deur die meganiese beskadiging van endodermale en parenchiem weefsel. Skade veroorsaak deur tweede, derde en vierde instar E. lanigerum was soortgelyk alhoewel die simptome meer beklemtoond was. Skade deur volwassenes het 'n meer duidelike swelsel by geïnfekteerde wortelareas ingesluit. Selwande het verhard totdat die wortel radiaalsgewys versterk was met skierenchiem weefsel en nie-geleidende xileemvate terwyl die kutikula grootliks toegeneem het deur die groei van kurkagtige kambiumweefsel. Daar was geen direkte verwantskap tussen die bevolkingsdinamika van E. lanigerum en dié van Xiphinema en Pratylenchus nematodes nie. Die voorkoms van E. lanigerum was seisoenaal terwyl P. penetrans en Xiphinema se getalle onvoorspelbaar gefluktueer het. Onbeskadigde wortel stikstofvlakke het ooreengestem met die normale wortel groeisiklus. Stikstof vlakke van galwortels was noemenswaardig laer as dié van onbeskadigde wortels, heel waarskynlik as gevolg van voeding deur E. lanigerum. Grond ryk aan fyn sand en klei het groter bevolkings van E. lanigerum en Xiphinema onderhou as sanderige gronde. Die aantal E. lanigerum in grondmonsters het goed ooreengestem met die skade indeks wat aan die monsters toegeken was. Die aantal Xiphinema in grondmonsters het ook goed ooreengestem met die beskadigingsindeks wat aan die monsters toegeken is weens vermoedelike Xiphinema skade simptome. Beide Biostart 2000® en Furfural® was effektief as beheeragente van die appelbloedluis. Furfural'", 'n afvalproduk van die suikerriet industrie, was egter minder effektief as Biostart 2000®, 'n produk bestaande uit 'n aktiveerder en drie bakterie spesies, Bacillus laterosporus, B. chitinosporus en B. licheniformis. Die bakterië in die Biostart 2000® behandelde potte kon vermeerder onder gunstige toestande terwyl Furfural® na elke besproeiing verdun het. Biostart 2000® is ook makliker om aan te maak as Furfural® aangesien die bestanddele van Biostart 2000® geredelik meng tot 'n wateroplosbare pasta, terwyl Furfural® 'n olierige vloeistofis wat moeilik 'n waterige suspensie vorm. Wortelskade het plaasgevind kort nadat E. lanigerum begin voed het, alhoewel daar geen duidelike verwantskap tussen E. lanigerum en nematode spesies voorgekom het nie. Die mees belowende omgewingsvriendelike beheermaatreël was Biostart 2000®.
Curran, Helen R. (Helen Rae). "Thecaphora anther-smut fungi : ecology and implications for CFR Oxalis species". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20293.
Testo completoENGLISH ABSTRACT: Only a limited number of systems involving anther-smut fungi have been studied, usually due to the economic significance of their crop plant hosts. A smut fungus of the genus Thecaphora has been discovered infecting Oxalis hosts in South Africa. This pathogenic fungus, Thecaphora capensis, produces dark-coloured spores in the anthers of host flowers, rendering it an anther-smut fungus. The host genus is the seventh largest plant genus in the Cape Floristic Region (CFR) and the largest geophytic genus of this region. Nine Oxalis species that host T. capensis have been identified across a wide distribution in the CFR of South Africa. A preliminary assessment of T. capensis infections of Oxalis was conducted in 2009, which provided a foundation for further research into the ecological and evolutionary consequences of hosting this fungus. In this study, a comprehensive host diversity assessment was conducted to determine the extent of infected Oxalis individuals within the CFR. Three new Oxalis host species for Thecaphora capensis were discovered. This brings the total number of known hosts to twelve. The morphological and reproductive effects of the fungus were assessed on two host species (O. incarnata and O. lanata) by comparing healthy and infected individuals of these species. Infection by Thecaphora capensis had a significantly negative effect on both of these factors. Host resources appear to be co-opted for fungal spore production, since floral morphological characters of infected individuals were reduced in size. Furthermore, infection by T. capensis ensured near-universal sterility in both hosts. Differences in floral characters and pollinator preferences for healthy Oxalis incarnata and O. lanata individuals from disease-free and diseased populations were compared to determine the evolutionary influence of Thecaphora capensis infections. It was shown that this pathogen can have a significant evolutionary influence on its hosts, showing its ability to shape flower size and pollinator activity in O. lanata, but not in O. incarnata. A need has therefore been identified to assess these evolutionary forces independently for each host and its pathogen before making erroneous assumptions for conservation practices. Plant pollinators play an integral role in plant fitness. Pollinator movements within a population are important when between-flower spore transfer by pollinators increases the likelihood of new infections. Pollinator movements may be influenced by host density and the frequency of diseased individuals, amongst other factors. Pollinators were found to mediate Thecaphora capensis spore transfers within diseased Oxalis populations. Host density and disease frequency affected the number of spores transferred under field and standardized conditions. More research is required to investigate confounding factors in these complex systems. This study highlighted the complexities of a fungal-plant-insect relationship, the evolutionary consequences of such fungal infections and the various factors influencing the likelihood of new infections. This research adds to the limited body of knowledge on multi-organismal interactions in the CFR and provides a base for more detailed future studies on this intriguing system.
AFRIKAANSE OPSOMMING: 'n Brandswam, wat deel is van die Thecaphora genus,is ontdek in 'n Oxalis blom waar dit die gasheer plant se blom gebruik om spore in te produseer. Die swam, Thecaphora capensis, produseer donker gekleurde spore in die helmknoppe van die blomme van gasheer plante, daarom word dit geklasifiseer as 'n brandswam van die helmknop. Die gasheer plante van die swam is deel van die genus Oxalis, die sewende grootste plant genus in die Kaapse Floristiese Streek (KFS) en die grootste geofitiese genus in die streek. Nege Oxalis species is al klaar identifiseer as gasheer plante van T. capensis. Hulle is versprei oor 'n groot area van die KFS van Suid Afrika. 'n Primêre ondersoek van T. capensis infeksies op Oxalis is in 2009 onderneem. Hierdie ondersoek het gelei tot meer vrae oor die sisteem en het 'n goeie fondasie geskep vir verdere navorsing rakende die ekologiese koste verbonde daaraan om as gasheer plant vir 'n swam op te tree. 'n Deeglike ondersoek is in die KFS aangepak om die Oxalis gasheer plante van die brand swam te identifiseer en om voort te bou op die basiskennis wat in die primêre ondersoek daargestel is. Drie nuwe Oxalis gasheer plante van Thecaphora capensis is ontdek. Die totale aantal gasheer plante staan nou op twaalf. Gesonde en geinfekteerde individuele gasheer plante is gebruik om die morfologiese en reproduktiewe effekte van die swam te toets in twee Oxalis spesies (O. incarnata en O. lanata). Die negatiewe gevolge om 'n gasheer plant van die brand swam te wees was duidelik toe gesonde en geinfekteerde individuele met mekaar vergelyk is. Dit kom voor asof gasheer plante se hulpbronne vir spoor produksie gebruik word, want hulle is morfologies kleiner en meestal steriel. Die evolusionêre effek van Thecaphora capensis op 'n populasie is getoets met gesonde individuele in populasies van twee Oxalis spesies. Blomkenmerke en insek bestuiwers van gesonde individue in gesonde en geinfekteerde populasies is ondersoek om die effekte van T. capensis op populasies te toets. Daar is suksesvol gedemonstreer dat swamme sterk evolusionêre kragte uitoefen, en die vermoë het om plantpopulasies te vorm en te verander, ofskoon nie in alle gevalle ewe sterk nie. Daarom is dit belangrik om die evolusionêre kragte vir elke gasheer plant en sy patogeen onafhanklik te assesseer, sonder om algemene aannames te maak in bewaringspraktyke. Plantbestuiwers speel 'n belangrike rol in die fiksheid van plante. Hulle kan hul fiksheid verbeter deur bestuiwers te lok met blomme en deur aspekte geassosieer met blomme. Die bewegingspatrone van plantbestuiwers is baie belangrik indien hulle helmknop-geproduseerde spore van brandswamme vervoer instede van stuifmeel, want dit vergroot die kanse vir nuwe infeksies. Die bewegingspatrone van plantbestuiwers word, onder andere, beinvloed deur die digtheid en frekwensie van geinfekteerde individue. Plantbestuiwers speel 'n belangrike rol in die vervoer van Thecaphora capensis spore in geinfekteerde Oxalis populasies. Die digtheid en frekwensie van geinfekteerde blomme het die vervoer van spore geaffekteer onder veld en gestandardiseerde kondisies, alhoewel baie veranderlikes so 'n komplekse natuurlike sisteem beinvloed. Hierdie studie beklemtoon die kompleksiteit van 'n fungus-plant-insek verhouding, die gevolge van so 'n interaksie en die verskeie faktore wat die waarskynlikheid van nuwe infeksies beinvloed. Tot dusver is daar 'n beperkte aantal sisteme soos hierdie bestudeer waarin 'n brandswam van die helmknop betrokke is, en die enkele beskikbare studies is onderneem meestal as gevolg van hulle ekonomiese effekte op landboukundig belangrike gasheer plante. Hierdie studie verteenwoordig 'n belangrike byvoeging tot die inter-organismiese studies in die KFS. 'n Holistiese ekologiese oorsig soos hierdie verskaf 'n belangrike basis vir toekomstige studies en bewarings- en bestuurspraktyke.
French, Robert John. "Leaf senescence and water stress in wheat seedlings /". Title page, contents and summary only, 1985. http://web4.library.adelaide.edu.au/theses/09PH/09phf875.pdf.
Testo completoDore, Dalin Shelley. "Grapevine rhizosphere bacteria : influence of diversity and function on two root diseases : a thesis submitted in fulfilment of the requirements for the degree of Master of Science at Lincoln University /". Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1305.
Testo completoRoets, Francois. "Ecology and systematics of South African Protea-associated Ophiostoma species". Thesis, Link to the online version, 2006. http://hdl.handle.net/10019.1/1469.
Testo completoLopes, Ueder Pedro. "Doenças do Morangueiro: Etiologia, epidemiologia e sensibilidade a fungicidas". Universidade Federal de Viçosa, 2014. http://locus.ufv.br/handle/123456789/1068.
Testo completoFundação de Amparo a Pesquisa do Estado de Minas Gerais
The culture of strawberry , Fragaria x ananassa Duch, has faced several problems, among which we highlight those caused by pathogens. In addition to widely known diseases such as gray mold, new diseases have caused serious damage to the crop. In order to study the various problems of strawberry culture, this study aimed to: i) identify the causal agent of a postharvest fruit rot in strawberry , ii) to study the temporal and spatial dynamics of the redness in strawberry, whose etiology is still unknown; iii) determine the species of Botrytis that cause gray mold in strawberry in Brazil iv) conduct a survey of the current situation of fungicides for control of gray mold on strawberry v) to study the sensitivity of isolates of B. cinerea to dicarboxamide and benzimidazole fungicides. In order to identify the causal agent of post harvest fruit rot of strawberry, isolates from symptomatic fruits were analyzed by morphologic and phylogenetic analyzes. After confirming the pathogenicity of the isolates, species identification as Neofusicoccum kwambonambiense and N. parvum was taken. This is the first report of the occurrence of Neofusicoccum kwambonambiense in Brazil and the first report of Neofusicoccum spp. causing rot in strawberry. By studying the pattern of temporal and spatial distribution of the redness of strawberry was conducted in four areas of commercial cultivation. With the data on incidence of disease progress curves and dispersion maps were constructed, and analysis of aggregation of plants by ordinary runs test. The results showed that the disease has a similar disease biotic distribution pattern similar to diseases which are dispersed in the row. To achieve other goals, isolates were obtained from plants with symptoms of gray mold on various properties of different cities in the states of Espírito Santo, Minas Gerais and São Paulo, totaling 200 isolates. Initially, a study was conducted to verify the occurrence of other species of Botrytis in the fields of strawberry cultivation in Brazil. For this, the extraction of DNA from all strains was performed, followed by PCR with the specific species and B. cinerea and B. caroliniana primers. Despite the morphological variation observed among isolates , all were identified as B. cinerea . The survey on the practices used to control gray mold on strawberry was performed directly with the producers, who were asked about the products used for the control of disease, efficiency of these products and use of the practice of removing diseased material . It was possible to observe many problems, especially reduced use of cultural control measures, the use of products not recommended for culture and the low level of knowledge of the farmers. Finally, the sensitivity analysis of the isolated main culture fungicides (iprodione , procymidone and thiophanate- methyl) was carried. Thus, a total of 100 isolates were grown in culture medium containing different doses of the fungicide was used. The results showed that 89% of isolates were insensitive to thiophanate-methyl fungicide, 36% to and 54% to procymidone. Considering the limited number of fungicides registered for the control of gray mold and the low sensitivity of isolates of B. cinerea to these products , it becomes difficult to manage this important disease of strawberry.
A cultura do morangueiro, Fragaria x ananassa Duch, tem enfrentado diversos problemas, dentre os quais destacam-se os causados por patógenos. Além de doenças amplamente conhecidas, como o mofo cinzento, novas doenças vêm causando sérios danos à cultura. Visando estudar os diversos problemas da cultura do morangueiro, este trabalho teve por objetivos: i) identificar o agente causal de uma podridão pós-colheita em frutos de morango; ii) estudar a dinâmica temporal e espacial do vermelhão do morangueiro, cuja etiologia é ainda desconhecida; iii) determinar as espécies de Botrytis que causam mofo cinzento em morangueiro no Brasil; iv) realizar um levantamento da situação atual do uso de fungicidas para controle do mofo cinzento do morangueiro; v) estudar a sensibilidade de isolados de B. cinerea aos fungicidas dicarboxamidas e benzimidazóis. A fim de identificar o agente causal da podridão pós-colheita de frutos de morango, isolados obtidos a partir de frutos sintomáticos foram analisados por meio de análises morfológicas e filogenéticas. Após a confirmação da patogenicidade dos isolados, foi feita a identificação das espécies como Neofusicoccum kwambonambiense e N. parvum. Este é o primeiro relato da ocorrência de Neofusicoccum kwambonambiense no Brasil e o primeiro relato de Neofusicoccum spp. causando podridão em morango. O estudo do padrão de distribuição temporal e espacial do vermelhão do morangueiro foi realizado em quatro áreas de cultivo comercial. Com os dados de incidência da doença foram construídas curvas de progresso e mapas de dispersão, além da análise de agregação de plantas pelo teste de ordinário runs. Os resultados mostraram que a doença apresenta comportamento semelhante a uma doença biótica com padrão de distribuição semelhante ao de doenças que se dispersam na linha de plantio. Para atingir os demais objetivos, foram obtidos isolados a partir de plantas com sintomas do mofo cinzento, em diversas propriedades de diferentes cidades nos estados do Espírito Santo, Minas Gerais e São Paulo, totalizando 200 isolados. Inicialmente, foi realizado um estudo para verificar a ocorrência de outra espécie de Botrytis nos campos de cultivo de morango no Brasil. Para isso, foi feita a extração de DNA de todos os isolados, seguindo-se à reação de PCR com primers específicos para as espécies B. cinerea e B. caroliniana. Apesar da variação morfológica observada entre os isolados, todos foram identificados como B. cinerea. O levantamento sobre as práticas utilizadas para controle do mofo cinzento do morangueiro foi realizado diretamente com os produtores, que foram questionados quanto aos produtos utilizados para o controle da doença, eficiência de controle dos produtos e uso da prática de retirada de material doente. Foi possível observar diversos problemas, destacando-se o reduzido uso de medidas de controle cultural, o uso de produtos não recomendados para a cultura e o baixo nível de conhecimento dos produtores. Por fim, foi realizada a análise de sensibilidade dos isolados aos principais fungicidas utilizados na cultura (iprodiona, procimidona e tiofanato-metílico). Para isso, foi utilizado um total de 100 isolados, os quais foram crescidos em meio de cultura contendo diferentes doses dos fungicidas. Os resultados mostraram que 89% dos isolados foram insensíveis ao fungicida tiofanato-metílico, 36% ao iprodiona e 54% ao procimidona. Considerando o número restrito de fungicidas registrados para o controle do mofo cinzento e a baixa sensibilidade dos isolados de B. cinerea a estes produtos, torna-se difícil o manejo dessa importante doença do morangueiro.
Viljanen-Rollinson, S. L. H. "Expression and detection of quantitative resistance to Erysiphe pisi DC. in pea (Pisum sativum L.)". Lincoln University, 1996. http://hdl.handle.net/10182/1657.
Testo completoGouveia, Estevam Manuel Rodriques. "Effects of arbuscular mycorrhiza on plant growth of four ornamental annuals (Dianthus chinensis x barbatus, Impatiens wallerana, Petunia x hybrida and Viola x wittrockiana) commonly grown in South Africa". Diss., 2016. http://hdl.handle.net/10500/22032.
Testo completoAgriculture, Animal Health and Human Ecology
M. Sc. (Ornamental Horticulture)
(5929676), Elizabeth A. French. "PLANT HORMONE PATHWAYS PLAY A CRUCIAL ROLE IN SOLANUM SPP. INTERACTIONS WITH THE SOIL ENVIRONMENT". Thesis, 2019.
Cerca il testo completoPaidi, Maya Devi. "Proteome in papaya roots in response to Phytophthora palmivora". Thesis, 2006. http://hdl.handle.net/10125/20741.
Testo completoQuinn, Geoffrey. "Towards an operational root disease mapping methodology through lidar integrated imaging spectroscopy". Thesis, 2010. http://hdl.handle.net/1828/3605.
Testo completoGraduate
Murray, Shane Louise. "Transformation of potatoes with the potato leafroll virus coat protein gene". Thesis, 1995. http://hdl.handle.net/10413/10348.
Testo completoThesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.
Papenfus, Heino Benoni. "Polyamines in Ecklonia maxima and their effects on plant growth". Thesis, 2012. http://hdl.handle.net/10413/8526.
Testo completoThesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
Mienie, Charlotte Maria Susanna. "Towards marker assisted selection for nematode resistance in soybean". Thesis, 2000. http://hdl.handle.net/10413/10262.
Testo completoThesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000.
Abrie, Amelia Letitia. "Regeneration and biotransformation of some members of the Cucurbitaceae". Thesis, 1998. http://hdl.handle.net/10413/10303.
Testo completoThesis (Ph.D.)-University of Natal, Pietermaritzburg, 1998.
Head, Elise. "Ecology of the Fergusonina fly and Fergusobia nematode gall association in South Australia". 2008. http://hdl.handle.net/2440/48390.
Testo completohttp://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1331016
Thesis (M.Sc.) -- University of Adelaide, School of Agriculture, Food and Wine, 2008
Smith, Julia P. "Differential growth of roots and shoots of Douglas-fir (Pseudotsuga menziesii) seedlings infested with Cinara pseudotsugae, and population dynamics of a parasitoid wasp (Pauesia sp.) of C. pseudotsugae". Thesis, 1997. http://hdl.handle.net/1957/33920.
Testo completoGraduation date: 1998
Taylor, Christine Helen. "Studies of camellia flower blight (Ciborinia camelliae Kohn) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science (Plant Pathology) at Massey University, Palmerston North, New Zealand". 2004. http://hdl.handle.net/10179/1722.
Testo completoCamellias are popular ornamental plants and the most serious pathogen of this plant is camellia flower blight, caused by the fungal pathogen Ciborinia camelliae Kohn. Ascospores of this fungus attack the flowers, turning them brown, rendering infected flowers unattractive. Little is known about the pathogen and control measures are not particularly effective. In this thesis, various aspects of the pathogen's basic and molecular biology and interaction with host species were studied. Surveys of the distribution and spread of C. camelliae within New Zealand determined that the pathogen was present in most regions of the North Island, and north and east coasts of the South Island. Over the distances and time involved, it appeared that the disease was spreading mainly by windborne ascospores rather than human transfer. Sclerotia were germinated out of season to increase the period during which ascospores were available for infection work. Greatest germination was achieved at low temperatures (5°C-10°C) in 24 h darkness. Isolate-specific primers were designed to the ribosomal DNA Internal Transcribed Spacer region to detect the pathogen in planta and distinguish between New Zealand isolates of C. camelliae and other fungal pathogens. Phylogenetic analysis of the ITS region with other Ciborinia, Sclerotinia and Botrytis species showed that C. camelliae was more closely related to S. sclerotiorum than other Ciborinia species. Two inoculation techniques for infecting Camellia petals with ascospores of C. camelliae were developed and tested. Inoculation using airborne ascospores in a settling chamber was a simple and quick method for testing large numbers of species for resistance. Inoculation of ascospores in suspension produced qualitative data, but was more time consuming. Of the four mechanisms of resistance tested, levels of aluminium hyperaccumulation and the presence of phenolic compounds did not correlate with resistance in Camellia species. The large uptake of aluminium, however, did indicate that Camellia species would be good plants for phytoremediation of acid soils. Some resistant species were found to have cell wall modifications and/or lignification of cell walls in response to C. camelliae infection and chitinase activity was found in most resistant Camellia species tested. Further research into these latter two mechanisms is recommended and indicates that the development of resistant Camellia cultivars is possible.
(6623615), Jesse A. Haarmann. "The Effect of Herbicide Respray Treatments and Timings on Regrowth of Four Weed Species". Thesis, 2019.
Cerca il testo completoControl of weeds that have survived a postemergence (POST) herbicide often need to be controlled in order to prevent seed production and interference with crops. The most efficacious herbicides and timings used for respray applications has not been determined in many problematic weed species. Previous research has demonstrated that weeds clipped to simulate a failed herbicide application responded differently to herbicide applications to regrowth based on herbicide used and weed species. Other research is conflicting as to the optimum timing of an herbicide respray application with various herbicides. Gaining a better understanding of how to maximize respray herbicide performance will help growers and land managers to preserve crop yield and prevent weed seed production in the event of POST contact herbicide failure. The objectives of this research were to determine the optimum respray herbicide and timing combinations for control of four problematic weed species in the midwestern United States that have survived an application of either glufosinate or fomesafen: waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer], Palmer amaranth (Amaranthus palmeri S. Watts), giant ragweed (Ambrosia trifida L.), and horseweed (Erigeron canadensis L). Through a series of field and greenhouse experiments we determined that respray herbicide, respray application timing, initial herbicide, and level of injury from the initial application influence efficacy of the respray herbicide in a species-specific manner. Waterhemp regrowth following a failed glufosinate application was controlled most effectively by applying glufosinate or fomesafen 7 to 11 days after initial treatment. When following fomesafen, applications of 2,4-D 3-7 days after initial treatment or glufosinate 7 to11 days after initial treatment were most effective. Control of Palmer amaranth regrowth following either initial herbicide is best achieved with respray applications of glufosinate, fomesafen, or 2,4-D applied no later than 7 days after initial treatment. The best strategy to control giant ragweed regrowth following a failed fomesafen applications is to apply 2,4-D, dicamba, fomesafen, or glufosinate at any timing between 3 and 11 days after initial treatment. Efficacy of the respray glufosinate application was maximized when applied 11 days after the initial application rather than 3 days after initial application. Horseweed regrowth was best controlled by 2,4-D, dicamba, or glufosinate applied at any timing between 3 and 11 days after the initial application. Where injury from the initial herbicide application is high, there were fewer differences among herbicide treatments and treatment timings. A greenhouse bioassay revealed that as waterhemp injury from an initial glufosinate application increases, control with a respray herbicide also increases. Therefore, complete control of weed regrowth is achieved more easily with increasing injury from the initial application. This research suggests that timing of herbicide respray applications is more urgent than previously thought, so scouting must be done within days of a contact herbicide application to ensure adequate control.
Hagerty, Christina H. "Mapping QTL for root rot resistance, root traits, and morphological trait in a common bean recombinant inbred population". Thesis, 2013. http://hdl.handle.net/1957/38263.
Testo completoGraduation date: 2013