In Manitoba, potato fields have been found to be infested with Verticillium dahliae, which can produce Vertcillium wilt disease severity of up to 90% and reduce yield. Potato producers have then an increased interest on use of green manures and organic amendments to control Verticillium wilt. The objectives of this research were to evaluate selected green manure and organic amendments for their ability to reduce propagule density of V. dahliae in soil, incidence and severity of Verticillium wilt, and to enhance potato yield in Manitoba. In addition, a second study was conducted for the purpose of studying the potential of mustard green manure and seed meal to inhibit the germination of microsclerotia. Findings suggest that composted-cattle-manure and oriental mustard seed-meal amendments have promise as an alternative strategy for the control of V. dahliae. However, only composted beef cattle manure reduced disease, increased potato yield and improved nutrient availability (P) in soil

In Manitoba, potato fields have been found to be infested with Verticillium dahliae, which can produce Vertcillium wilt disease severity of up to 90% and reduce yield. Potato producers have then an increased interest on use of green manures and organic amendments to control Verticillium wilt. The objectives of this research were to evaluate selected green manure and organic amendments for their ability to reduce propagule density of V. dahliae in soil, incidence and severity of Verticillium wilt, and to enhance potato yield in Manitoba. In addition, a second study was conducted for the purpose of studying the potential of mustard green manure and seed meal to inhibit the germination of microsclerotia. Findings suggest that composted-cattle-manure and oriental mustard seed-meal amendments have promise as an alternative strategy for the control of V. dahliae. However, only composted beef cattle manure reduced disease, increased potato yield and improved nutrient availability (P) in soil

Globally emphasis has been given to identify emerging and re-emerging pathogens. Rapid urban expansion creates a problem which is two-fold. Firstly, increasing slum living conditions due to inadequate rate of infrastructure development results in an increased reliance on natural resources, including the capture and consumption of surrounding wildlife to subsist, thereby facilitating the transfer of emergent zoonotic pathogens. Secondly, through activities such as pollution or alien species introductions, the rapid transformation of once pristine environments, alters natural systems, potentially exposing these environments to new bacterial pathogens. Therefore, the main aim of this study was to assess overlooked bacterial species harboured by four host species (Bathyergus suillus, Georychus capensis, Cryptomys hottentotus hottentotus and Fukomys damarensis) belonging to the subterranean rodent family Bathyergidae, which inhabit an environment well-suited for an array of bacterial species, and which varied in their exposure to human settlements. Bacterial prevalence and diversity was initially evaluated using broad-range PCR techniques in combination with nucleotide sequencing. This revealed high levels of bacterial prevalence (82.91%) and mixed infections (22.60%) in bathyergid species. Two bacterial groups, the Bacillus cereus complex (a group of soil-dwelling bacterial strains with pathogenic potential with an overall prevalence of 8.55%) and haemotropic Mycoplasma strains (vector-borne bacterial strains of zoonotic potential with an overall prevalence of 1.28%) were subsequently selected for further genetic analysis with genus and species-specific PCRs. Bacillus molecular screening and phylogenetic analyses was achieved by targeting four gene regions with seven published primer assays and two novel PCR assays. This enabled identification of two B. cereus complex strains in bathyergid lungs and revealed an overall B. cereus complex prevalence of 17.95% for the 234 bathyergid lung samples screened. Bacillus genome prevalence was significantly higher in B. suillus individuals (45.35%), sampled in a peri-urban environment, compared to the other bathyergid species sampled from pristine habitats (ranging from 0% - 4.44%). Anthropogenic activities in the area where B. suillus was sampled could, at least partially, attribute to the perceived difference between urban and naturally sampled bathyergid species, highlighting the role of B. suillus to act as both a reservoir of potentially zoonotic pathogens and as a sentinel for anthropogenic soiling. Mycoplasma molecular screening using three different PCR assays, all targeting the 16S rRNA gene region, confirmed an overall haemotropic Mycoplasma prevalence of 24.13% in the 286 bathyergid organs (lung, spleen and liver) screened. A significantly higher prevalence and diversity of haemotropic Mycoplasma strains was found in B. suillus lungs (41.86%) compared to its naturally occurring relatives (ranging from 0%-36%). Phylogenetic analyses identified six novel haemotropic Mycoplasma strains, all grouping within a discrete monophyletic cluster, sister to Mycoplasma coccoides, and comprising two well-supported sub-clusters. The human introduction of commensal rodents harbouring Mycoplasma strains transferred through cosmopolitan arthropod vectors to indigenous bathyergids, likely underlies the higher prevalence in urban areas, although other biotic and abiotic factors affecting ectoparasite load also merit consideration. The data generated by the current study indicate the need to identify largely overlooked and potentially zoonotic bacterial pathogens in subterranean mammals and emphasises the importance of monitoring anthropogenically-introduced, opportunistic pathogens and the threats they pose to vulnerable communities and co-occurring, free-living animal species / Dissertation (MSc)--University of Pretoria, 2017. / Airports Company of South Africa (ACSA) / National Research Foundation (NRF) / Zoology and Entomology / MSc / Unrestricted

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-01-10T16:10:06Z No. of bitstreams: 1 IzabelMG_TESE.pdf: 880498 bytes, checksum: 2febd06d5341085eddd00966347b4504 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-01-24T14:45:40Z (GMT) No. of bitstreams: 1 IzabelMG_TESE.pdf: 880498 bytes, checksum: 2febd06d5341085eddd00966347b4504 (MD5) / Made available in DSpace on 2017-03-21T14:50:07Z (GMT). No. of bitstreams: 1 IzabelMG_TESE.pdf: 880498 bytes, checksum: 2febd06d5341085eddd00966347b4504 (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The melon cultivation in semi-arid northeast in consecutive cycles has generated problems caused by fungi inhabitants of the soil, such as Fusarium solani and M. cannonballus. The use of resistant cultivars is an interesting measure for the management of the disease. For this reason, it is important identify sources of resistance and study their inheritance. The objectives of this work were: a) to evaluate the reaction of melon accessions to F. solani f. sp. Cucurbitae; b) to evaluate the reaction of accessions and study the inheritance of resistance of accession AC-33 to M. cannonballus. In the first experiment, we evaluated twenty-one accessions in a completely randomized design in greenhouse. Two isolates were inoculated fifteen days after sowing by the toothpick. The assessment was done Thirty days after inoculation with a scale scored from zero to four. The accessions AC-01, AC-09, AC-42, AC-45, AC-50 and the cultivar 'Doublon' are the most promising materials for use in breeding programs for resistance to F. solani or as rootstocks. In the second experiment, sixteen accessions and line OF-02 were evaluated in a completely randomized design. We used the isolated MC-16 to infestation of a mixture (1:1:1) with soil, peat, and sand previously sterilized with the addition of a concentration of 20 u.f.c./g soil. The evaluation was performed at 45 days using a rating scale (1-5). In the third experiment, we investigated the inheritance of resistance of accession AC-33 crossed with line OF-02 (susceptible). We observed variability in the germplasm investigated for reaction to the fungus. The AC-33 is highly resistant to access M. cannonballus and its resistance is controlled by a major gene with additive and dominant effects and polygenes with additive effects / O cultivo do meloeiro no semiárido nordestino em ciclos consecutivos tem gerado problemas causados por fungos habitantes do solo, como Fusarium solani e Monosporascus cannonballus. O uso de cultivares resistentes é uma medida interessante para o manejo da doença. Em razão disso, é importante que fontes de resistência sejam identificadas e se conheça a herança da resistência. Os objetivos do presente trabalho foram: a) avaliar a reação de acessos de meloeiro a F. solani f. sp. cucurbitae e b) avaliar a reação de acessos e estudar a herança da resistência do acesso AC-33 a M. cannonballus. No primeiro experimento, foram avaliados 21 acessos em um delineamento inteiramente casualizado em casa-de-vegetação. Foram inoculados dois isolados, com o método do palito, aos 15 dias após a semeadura. A avaliação dos acessos foi realizada 30 dias após a inoculação, com uma escala de 0 a 4. Os acessos AC-01, AC-09, AC-42, AC-45 e AC-50 e a cultivar ‘Doublon’ são os materiais mais promissores para uso em programas de melhoramento genético visando à resistência a F. solani ou como porta-enxertos. No segundo experimento, foram avaliados 16 acessos e a linhagem OF-02 em um delineamento inteiramente casualizado. Utilizou-se o isolado MC-16 para infestação de mistura em volume de 1:1:1 de terra, turfa e areia, previamente esterilizada com a adição de uma concentração 20 u.f.c./g de solo. A avaliação foi realizada aos 45 dias utilizando uma escala de notas (1 a 5). No terceiro experimento, investigou-se a herança da resistência do acesso AC-33 (resistente) cruzado com a linhagem OF-02 (suscetível). Observou-se a existência de variabilidade no germoplasma investigado para reação ao fungo. O acesso AC-33 é altamente resistente a M. cannonballus e sua resistência é controlada por um gene maior de efeito aditivo e dominante e poligenes de efeitos aditivos / 2017-01-10