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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Toy(ed) soldiers : constructions of white adolescent masculinity in Mark Behr's narratives.

Swinstead, Kim Tracy. January 2007 (has links)
This thesis is a literary thematic analysis of Mark Behr's novels The Smell of Apples (1996) and Embrace (2000). Through these novels, Behr explores the nature of masculine identities and the ways in which they are developed through a process of adolescent males observing and interacting with their parents and the society in which they live. The development of the two protagonists is traced and white hegemonic attitudes to masculinity in South Africa are exposed. The novels are of importance as these hegemonic attitudes continue to exist within South Africa today. The focus of this analysis is on white adolescent masculinities and the ways in which Behr illustrates the effects of apartheid society on their development. The study makes an in-depth analysis of the plot and themes and the way in which these guide the reader into a critical awareness of socially constructed masculine identities. Each of the four themes - namely, sexuality, race, gender and land - is explored in this thesis and careful consideration is given to the techniques Behr uses in his writing. Of importance to this thesis are the interrelationships between character, themes and the context of the novels. While the novels are not regarded as a case study, this thesis repeatedly demonstrates the socio-political awareness that Behr uses in order to offer his reader insight into the significant realities that have faced adolescent males as they construct their identities. / Thesis (M.A.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.
322

The screening of potential fungal antagonists of pseudothecial formation by the apple scab pathogen : Venturia inaequalis

Philion, Vincent January 1994 (has links)
In 1992, a research program was initiated to select suitable antagonists against the saprophytic (or winter) phase of the apple scab pathogen, Venturia inaequalis. An improved method for the mass screening of a vast collection of fungi was developed for this purpose. Some of the previously reported criteria such as leaf rheology and overwintering structure production proved unreliable or fastidious and cannot be used for in vitro antagonist selection. The main antagonism selection criterium retained was the in vitro inhibition of ascospore formation. To measure ascospore production, a simplified method of in vitro pseudothecia production was devised. This new method eliminates the need for prior conidia production by using a mycelial suspension and greatly reduces the risks of sterile mating by using a cocktail of Venturia inaequalis strains of different origins. Finally, the production cycle duration was reduced by varying the incubation temperature during the simulated winter. Moreover, a quick and efficient method of ascospore collection was developed. Ascospores were forcibly ejected in a large scale bubbler type apparatus in only one hour. This bubbler can be used for other studies including axenically produced ascospores. This new method compared favourably to the previously reported method and was used to screen a collection of about forty-two fungi. Six proved to significantly reduce the ascospore production of Venturia inaequalis. Two were as effective as Athelia bombacina, a previously reported antagonist of pseudothecia formation and inhibited over 98% of the ascospore production. These new organisms are now available for future field tests. Future selections from a large collection of saprophytes can now be based on a reliable and simple in vitro screening methodology.
323

A study of fungal leaf decomposition in relation to biological control of the apple scab pathogen, Venturia inaequalis

Bernier, Julie January 1995 (has links)
Venturia inaequalis, the causal agent of apple scab, overwinters in apple leaves on the orchard floor. To develop a control strategy based on the prevention of the maturation of overwintering pseudothecia, a sampling of fungi colonizing dead apple leaves was conducted from different orchard floors in Quebec during the spring and fall of 1993. A total of 345 different isolates were obtained, from which fifteen genera have never been previously recorded as colonizers of apple leaves in North America. Small differences were detected in genera richness among orchards but the fungal composition of each orchard was fairly unique. Different tests on growth on amended media and leaf decomposition demonstrated that leaf degradation is not a reliable parameter alone to screen antagonist against V. inaequalis. No significant relation between growth on amended media, leaf rheology and ascospore inhibition was detected. However, 40 fungi reduced significantly ascospore production more than 87% compared to the control (V. inaequalis only). Of these antagonists, 30% decomposed apple leaves, suggesting that competition for the substrate is involved in the mode of action of at least one third of the antagonits detected. Other possible modes of antagonism are discussed.
324

Responses of Venturia inaequalis to sanitation and regional climate differences in South Africa

Von Diest, Saskia Gudrun 04 1900 (has links)
Thesis (PhD(Agric))--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The apple industry in South Africa currently relies entirely on chemical fungicides to control apple scab, caused by Venturia inaequalis. In this dissertation, alterative management strategies against V. inaequalis were tested for the first time in South Africa. New information on the behaviour of the sexual winter phase of V. inaequalis in different climatic conditions was found and sources of asexual inoculum overwintering in apple orchards were identified. The effect of leaf shredding on fruit and leaf scab incidence and severity was tested against a non-shredded, non-sprayed negative control, a positive control that followed a commercial fungicide programme and a combined treatment of a commercial fungicide programme with leaf shredding, from 2010 to 2013. Reductions in fruit and leaf scab incidence and severity in the leaf shredding treatment were significantly lower compared to the negative control. Quantitative real-time polymerase chain reaction (qPCR) of airborne ascospores trapped using volumetric spore traps was used to measure the reduction in airborne ascospores in the shredded plots, and confirmed the efficacy of shredding found by comparing scab incidence and severity on fruit and leaves. Shredding twice during leaf-drop increased the efficacy of the treatment. Results indicate that leaf shredding should be integrated into scab management strategies in future. However, practical considerations unique to South African orchards, e.g. timing of leaf shredding relative to leaf-drop and orchard layouts, need to be addressed. Pseudothecial densities (PD, number of pseudothecia per fertile lesion) and ascal densities (AD, number of asci per pseudothecium) were compared between in Koue Bokkeveld (KB), a cold winter region, and Elgin (EL), a warm winter region experiencing climate warming, in 2012 and 2013. Scabbed leaves were detached during leaf-drop and overwintered in their region of origin and in the other region. The PD in leaves collected in KB and overwintered in KB was significantly higher than for leaves collected in EL and overwintered in EL, and leaves collected in KB and overwintered in EL. These results agreed with what was expected, as temperature during pseudothecial formation (i.e. the first four weeks after leaf-drop) was significantly lower in KB than in EL. However, the PD for leaves collected in EL and overwintered in EL did not differ significantly from EL leaves overwintered in KB. AD values in all treatments did not differ significantly from one another. Results suggest that factors other than temperature may be involved in controlling PD, e.g. the EL population may include strains not present in the KB population, with higher optimal temperatures for pseudothecial formation. Apple buds and pygmy apples were collected and tested for presence, number and viability of conidia in 2010, 2011 and 2012. Pygmy apples are small, late season fruit that remain attached to the tree throughout winter, especially in regions with warmer winters where trees do not experience sufficient chilling to complete dormancy. High conidial numbers were found on outer bud tissue and low numbers on inner bud tissue, but viable conidia were only found on inner bud tissue, using microscopy, and generally in orchards with high scab levels in the previous season. Molecular methods using PCR-RFLP and qPCR confirmed the presence of high amounts of V. inaequalis DNA in outer bud tissues, although calculated conidial amounts were higher than data obtained when using microscopy, which could indicate presence of mycelia not detected during microscopic examination. Higher numbers of conidia with higher percentage viability were found on pygmy apples, which are a more likely source of asexual inoculum in South African apple orchards than the low number of viable conidia on inner bud tissue. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse appelbedryf is tans afhanklik van chemiese swamdoders vir die beheer van die appelskurf patogeen, Venturia inaequalis. In hierdie proefskrif is alternatiewe bestuurstrategiëe vir die eerste keer in Suid-Afrika ondersoek. Nuwe inligting te opsigte van die gedrag van die geslagtelike winterfase van V. inaequalis, is onder verskillende klimaatstoestande ingewin en bronne van die oorwinterende ongeslagtelike inokulum in appelboorde, is identifiseer. Die invloed van blaarversnippering op die voorkoms en erns van appelskurf op vrugte en blare, is vanaf 2010 tot 2013 ondersoek en met ʼn negatiewe kontrole (onversnipperde blare sonder spuitprogram), ʼn positiewe kontrole (ʼn kommersiële swamdoderspuitprogram is gevolg) en gekombineerde behandelings (kommersiële swamdoderspuitprogram en blaarversnippering) vergelyk. Daar was ʼn betekenisvolle verskil in die voorkoms en erns van skurf op vrugte en blare met blaarversnippering teenoor die negatiewe kontrole. Kwantitatiewe intydse polimerase kettingvermeerderingsreaksie (kPKR) van luggedraagde askospore, vasgevang in volumetriese lokvalle, is gebruik om die afname van luggedraagde askospore in versnipperde behandelings te meet. Die doeltreffendheid van versnippering as behandeling, is bevestig deur die voorkoms van appelskurf te vergelyk met die ernstigheidsgraad daarvan op vrugte en blare. Die uitvoer van blaarversnippering twee keer gedurende die blaarvalperiode het die effektiwiteit van hierdie behandeling verhoog. Hiervan kan dus afgelei word dat blaarversnippering voordelig sal wees vir die bestuur van appelskurf en in toekomstige bestuurspraktyke ingesluit moet word. Praktiese oorwegings, uniek aan Suid-Afrikaanse boorde, soos boorduitleg en die tydsberekening van blaarversnippering teenoor blaarval, moet egter in ag geneem word. Pseudothesiale digtheid (PD; die aantal pseudothesia per vrugbare letsel) en askale digtheid (AD; die aantal aski per pseudothesium) is gedurende 2012 en 2013 vir die Koue Bokkeveld (KB), 'n koue winterstreek, en warm winterstreek Elgin (EL), 'n winterstreek wat klimaatsverwarming ervaar, vergelyk. Blare, met skurf, is gedurende blaarval gepluk en oorwinter in hul gebied van oorsprong, asook in die ander klimaatstreek. Blare wat in KB versamel is en in KB oorwinter het, se PD was aansienlik hoër as dié wat in EL versamel is en in EL oorwinter het, sowel as dié wat in KB versamel is en in EL oorwinter het. Hierdie resultate stem ooreen met wat verwag is, om rede die temperatuur gedurende pseudothesiale vorming, d.w.s. die eerste vier weke na blaarval, aansienlik laer in KB as in EL was. Die PD van blare wat in EL versamel en daar oorwinter het, het egter nie betekenisvol verskil van blare wat in KB oorwinter het nie. Die AD-waardes tussen behandelings verskil nie noemenswaardig nie en word as onbeduidend beskou. Die verkrygde resultate dui aan dat daar ander faktore as temperatuur betrokke is by die beheer van PD, bv. die EL-skurfpopulasie, waar die warmer klimaat meer optimaal is vir pseudothesiale vorming, rasse wat nie in die KB-bevolking teenwoordig is nie, mag insluit. Appelknoppe en dwerg-appels is gedurende 2010, 2011 en 2012 versamel en vir die teenwoordigheid, aantal en lewensvatbaarheid van konidiospore getoets. Dwergappels is klein laatseisoen appeltjies wat reg deur die winter aan die boom bly hang; veral in die streke met warmer winters waar die bome nie die nodige koue ervaar om dormansie te voltooi nie. Met behulp van mikroskopie is ʼn hoë aantal spore op die buitenste knopweefsel en lae getalle in die binneweefsel bespeur; maar lewensvatbare spore is net in die binneweefsel van knoppe waargeneem, wat hoofsaaklik afkomstig is van boorde wat hoë vlakke van appelskurf in die vorige seisoen ervaar het. Molekulêre tegnieke, PKR-RFLP en kPKR, is gebruik vir bepaling van V. inequalis DNA hoeveelhede op die buitenste knopweefsel. Hoër getalle konidiospore is met die molekulêre analise gevind, as dié verkry met mikroskopiese ondersoek en dui op die moontlike teenwoordigheid van miselium wat nie met visuele waarneming sigbaar was nie. Meer konidiospore met 'n hoër vlak van lewensvatbaarheid is op dwerg-apples gevind en dit is moontlik 'n meer waarskynlike bron van ongeslagtelike inokulum in Suid-Afrikaanse appelboorde, as die lae getalle van lewensvatbare konidiospore op die binneweefsel van die appelknoppe.
325

Fenolinių junginių kiekinės sudėties tyrimas Lietuvoje auginamų obelų veislių skirtingų poskiepių ir kultivavimo sistemų obuoliuose / Study of quantitative composition of phenolic compounds in Lithuania grown apples from different rootstocks and cultivation systems

Budrys, Evaldas 18 June 2014 (has links)
Ištirti Lietuvoje auginamų obelų veislių skirtingų poskiepių ir kultivavimo sistemų obuolių fenolinių junginių kiekinės sudėties įvairovę bei įvertinti antioksidantinį aktyvumą. / To evaluate quantitative composition and antioxidant activity of phenolic compounds in Lithuania grown apples from different rootstocks and cultivation systems.
326

Susceptibility of apple cultivars to Venturia inaequalis

Dewdney, Megan. January 2000 (has links)
Apple scab is one of the greatest apple management problems throughout the world Much work has been done on cultivars resistant to Venturia inaequalis (Cke.) Wint., but few have been a commercial success. This frequently leaves fungicides as the only control method used. As Quebec growers select new cultivars for planting, more information is needed on their relative susceptibility for efficient scab control. In this light, 21 cultivars common to central and eastern Canada, were examined for their relative susceptibility using several components of partial resistance; disease severity, incubation period, latent period, lesion size, and conidial production. The cultivars used were Cortland, Early Geneva, Empire, Golden Delicious, Golden Russet, Idared, Jersey Mac, Jonagold, Jonamac, Lobo, Lodi, Summerland McIntosh, Mutsu (Crispin), Northern Spy, Paulared, Red Cortland, Red Delicious, Royal Gala, Spartan, Sunrise, and Vista Bella. A final ranking of the cultivars and selection of partial resistance components was done using the principal components analysis. (Abstract shortened by UMI.)
327

Field evaluation of fungal antagonists for the reduction of inoculum of Venturia inaequalis (Cke.) Wint.

Ordon, Violetta. January 1998 (has links)
The use of a biofungicide on the perfect stage of V. inaequalis on leaf litter is one potential way to reduce the number of fungicides used to control apple scab. The previous in vitro screenings of Quebec mycoflora have shown that several isolates are able to significantly reduce the primary inoculum of the pathogen. Among the screened fungi, P176A and P130A, reduced over 98% of the ascospore production and were as effective as Athelia bombacina. However, because in vitro tests are generally poor predictors of in vivo assays a re-evaluation of the antagonists was done under field conditions. Eight fungal isolates, leaf shredding, and two comparative treatments (A. bombacina, 5% urea) were applied to intact scabbed leaves in October 1994 and 1995. After the treatments, the leaves overwintered on the orchard ground until the next spring. In April, samples of treated leaves were randomly selected and placed in spore traps to collect the ejected ascospores during rainfall. Since the primary inoculum was ejected during a four-month period, antagonism was based upon ratings taken throughout the whole ejection season. To evaluate the effect of incubation conditions on the antagonistic performance we incubated separately, in vitro and in vivo, sterile leaf disks which were artificially inoculated with V. inaequalis and fungal isolates. (Abstract shortened by UMI.)
328

The long term effects of apple replant disease treatments on growth and yield of apple trees and an examination of Pratylenchus and Pythium as causal agents /

MacDonald, Gerald January 1988 (has links)
No description available.
329

Studies on silver leaf disease of stone and pome fruit trees [microform]

Bishop, Geoffrey C. January 1978 (has links)
vi, 128 leaves : photos, tables ; 30 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1978
330

Organic apple production in Sweden : cultivation and cultivars /

Jönsson, Åsa, January 2007 (has links) (PDF)
Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2007. / Härtill 5 uppsatser.

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