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Dissertations / Theses on the topic 'Diseases and pests'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 July 2025

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1

Terry, Alan J. "Control of pests and diseases." Thesis, University of Surrey, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505965.

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2

George, Adrienne. "Cataloguing Diseases and Pests in Captive Corals." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3115.

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Stony corals (Order Scleractinia) are susceptible to a variety of diseases, which can occur from abiotic or biotic factors, or a combination of both. Public aquaria provide opportunities to study coral disease. Because coral mucus is the first line of defense against disease, the Biolog EcoplateTM is a useful tool to detect differences in microbial assemblages in the surface mucopolysaccharide (mucus) layer when comparing healthy and diseased corals. Histological examination is essential to document structural changes in coral tissue in response to diseases. This study identifies and character

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3

Melander, Margareta. "Transgenic resistance to pathogens and pests /." Alnarp : Dept. of Crop Science, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a496.pdf.

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4

Marino, Dante. "Screening of Germplasm Accessions from the Brassica Species for Resistance against PG3 and PG4 Isolates of Blackleg." Thesis, North Dakota State University, 2011. https://hdl.handle.net/10365/29053.

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Blackleg is a disease of canola and rapeseed cultivars that is caused by the fungus Leptosphaeria maculans (Desm.) Ces. & de Not., and it is by far the most destructive pathogen of canola in North America. In recent years, blackleg strains belonging to pathogenicity groups (PG) 3 and 4 have been discovered in North Dakota. Recent outbreaks of the disease have added a sense of urgency to characterize the risk these new strains represent for the canola industry and to identify sources of resistance against them. Thus, the objectives of this study were to screen germplasm collections of Brassica

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5

Denman, Sandra. "Botryosphaeria diseases of proteaceae." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52721.

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Dissertation (PhD (Agric))--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: Fungi belonging to the genus Botryosphaeria are heterotrophic micromycetes that can be pathogens on woody plants. They cause serious, and in some cases devastating losses to crops through leaf necrosis, stem cankers and plant death. The Proteaceae cut-flower industry in South Africa accounts for 70% of the national cut-flower enterprise. Botryosphaeria diseases are a major impediment to production and trade of Proteaceae and there is an urgent need to investigate the etiology, epidemiology and control of t

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6

Lubbe, Carolien M. "Colletotrichum diseases of Proteaceae." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/53732.

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Thesis (MSc)--Stellenbosch University, 2004.<br>ENGLISH ABSTRACT: This thesis consists of four chapters that present research findings on Colletotrichum diseases associated with Proteaceae worldwide. The first chapter is a review of literature regarding the taxonomy and histology of Colletotrichum species associated with Proteaceae. The literature is not restricted to Proteaceae hosts, as information regarding Colletotrichum on Proteaceae is very limited. In chapter two, Colletotrichum spp. associated with proteaceous hosts growing in various parts of the world were identified based on m

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7

Noronha, Christine M. (Christine Mary). "Effects of density and host plant type on fecundity and survival of Delia radicum (Bouché), D. Antiqua (Meigen) and D. Platura (Meigen) (Diptera: Anthomyiidae)." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41017.

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The effects of intraspecific and interspecific competition, host plant, and prior host plant experience on fecundity, rate of oviposition and mortality of adults and larval survival of Delia radicum Bouche (Cabbage Maggot (CM)), D. antiqua Meigen (Onion Maggot (OM)), and D. platura Meigen (Seed Corn Maggot (SCM)), were studied on cabbage, onion and bean plants.<br>An optimum density for maximum fecundity per female was observed when the four experimental densities were compared. This optimum density was higher on host than on non-host plants. CM females were host specific and did not oviposit

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8

Wakgari, Waktola (Waktola Muleta). "Biology, ecology and management of white wax scale, Ceroplastes destructor Newstead (Hemiptera: Coccidae), on citrus and syzygium." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51637.

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Thesis (PhD)--University of Stellenbosch, 2000.<br>ENGLISH ABSTRACT: The population density of the white wax scale, Ceroplastes destructor Newstead, has increased since 1994 in certain areas of Western and parts of Eastern Cape Provinces of South Africa where citrus is grown, particularly on Citrus reticulata (Blanco). A study was conducted to investigate its morphology, biology and ecology as contributions to the development of a sound integrated management programme. Characteristics of the immature stages and adult females were described and illustrated from field-collected and slide-

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9

Rodriguez, Juan Jose. "Movement and Accumulation of Candidatus Liberibacter Solanacearum in Potato Plants." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26726.

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A new disease affecting potatoes was first detected in Mexico in 1993. Affected plants had aerial symptoms similar to those caused by potato purple top and psyllid yellows, but tubers had internal brown discoloration when sliced and dark stripes and streaks when processed to produce potato chips. The disease has been found in many potato production areas in Guatemala, Mexico, Honduras, New Zealand and the United States. The disease, termed Zebra Chip (ZC), has been associated with the presence of heavy infestations of the potato-tomato psyllid (Bactericera cockerelli). In 2009, a research grou

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10

Kawchuk, Lawrence Michael. "Molecular characterization of potato leafroll luteovirus and development of genetically engineered resistance." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30684.

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Complementary DNA (cDNA) clones representing approximately 5800 nucleotides of potato leafroll virus (PLRV) genomic RNA were generated, restriction-mapped, and partially sequenced. Within one of the cDNA clones an open reading frame (ORF) that could encode a 23 kDa protein was identified and further characterized. Comparison of the deduced amino acid sequence with the coat protein amino acid sequence of the PAV strain of barley yellow dwarf luteovirus (BYDV-PAV) showed significant similarity. This observation together with its size and internal location within the genome suggested that this ge

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11

Lee, Yi-Chen. "EVALUATION OF SOYBEAN DISEASES AND PESTS USING TWO ADVANCED BREEDING POPULATIONS." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1927.

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Soybean (Glycine max [L.] Merr.) is one of the most important crops in the world. The average annual yield losses due to soybean diseases and pests are estimated to be around 11% in the United States. Soybean yield losses due to sudden death syndrome (SDS), caused by the fungus Fusarium virguliforme O'Donnell & T. Aoki have been problematic in majority of the soybean producing states. In recent years, reniform nematode (RN, Rotylenchulus reniformis Linford and Oliveira) and frogeye leaf spot (FLS), caused by the fungus Cercospora sojina K. Hara have emerged as a major problem in the southern s

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12

Gutschow, Minique. "Resistance to Botrytis cinerea in parts of leaves and bunches of grapevine." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52435.

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Thesis (MScAgric)--University of Stellenbosch, 2001.<br>ENGLISH ABSTRACT: Knowledge of the presence of Botrytis cinerea in morphological parts of bunches and leaves of grapevine would help to find a reliable, sensitive, and specific assay to verify the actual occurrence of latent infection, and to plan strategies for the effective control of B. cinerea bunch rot. The aim of this study was (i) to determine natural B. cinerea infection at specific sites in leaves and bunches of grapevine at different phenological stages, and (ii) to determine resistance in the morphological parts to diseas

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13

Jensen, Paul. "An evaluation of potential apple replant disease treatments for Quebec /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63295.

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14

MacDonald, Gerald. "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 /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61700.

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15

Kelly, Jack, and Mary W. Olsen. "Problems and Pests of Agave, Aloe, Cactus and Yucca." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2011. http://hdl.handle.net/10150/144789.

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12 pp.<br>plant disease bulletins; July 2006 original publishing date, rev. 10/08<br>Cacti, agaves and yuccas are classified as succulents, plants that have highly specialized anatomical features such as thick waxy cuticles, fleshy or minimal leaves, modified leaves (spines), and roots with extra storage capabilities for food and water. These modifications allow them to survive and thrive in harsh desert environments. They survive long periods of drought in areas of sparse rainfall and intense heat. During stressful periods, many succulents cease to grow, drop unnecessary leaves, dehydrate an

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16

Arcelin, Rachel. "A survey of carrot diseases on muck soils in the Montreal area and evaluation of partial resistance to Cercospora blight in carrot cultivars /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60521.

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During the summer 1988 and 1989, surveys were conducted on the muck soils, South of Montreal to estimate the prevalence and incidence of the carrot diseases. Cercospora blight was the most prevalent disease; 91% and 96% of the fields and 99% and 92% of the plants sampled were diseased in 1988 and 1989, respectively. In decreasing order of occurrence the diseases present were: Crown gall, Alternaria blight, Root Knot, Sclerotinia rot and Aster yellows.<br>Greenhouse and field studies were carried out to evaluate partial resistance to Cercospora blight in 111 carrot cultivars based on the mean i

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17

Wellings, Colin Ross. "Host: pathogen studies of wheat stripe rust in Australia." Thesis, Department of Agricultural Genetics and Biometry, 1986. http://hdl.handle.net/2123/14544.

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18

Chauhan, Ramola. "A study of filamentous viruses in maize and smallgrains." Master's thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/22013.

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Bibliography: pages 175-184.<br>The occurrence of maize dwarf mosaic virus (MDMV) in field grown maize was investigated. For this purpose, maize showing mosiac symptoms was collected from different maize growing areas in South Africa by Prof. M.B. von Wechmar. These samples from Transvaal, Orange Free State and Natal were then investigated for the presence of MDMV and possible strains of this virus. Three virus isolates were purified and partially characterised. These isolates were serologically compared together with a fourth isolate SCMV 4975, obtained from the U.S., to establish strain rela

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19

Loots, Shilo. "Isolation and characterization of Diuraphis noxia induced sequences from wheat line PI 294994." Diss., University of Pretoria, 2002. http://hdl.handle.net/2263/25763.

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20

Laberge, Christiane. "Production and diseases of Jerusalem artichoke." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65448.

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21

Wilkes, Meredith Ann. "The Role Of Hydroxamic Acids In Take-all Resistance." Thesis, The University of Sydney, 1997. https://hdl.handle.net/2123/27618.

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The occurrence of hydroxamic acids (Hx) and their affects on take-all have been investigated in this study. An improved HPLC procedure for the separation and quantification of Hx in wheat, rye and triticale roots was established. This method completely separated 2,4-Dihydroxy—1,4— benzoxazin—3-one (DIBOA), 2 , 4-Dihydroxy - 7- methoxy - 1 4- benzoxazin -3-one (DIMBOA), 2(3)-benzoxazolinone (BOA) and 6- methoxybenzoxazolinone (MBOA) within 17 min. DIMBOA was the only Hx found in wheat roots, whereas both DIMBOA and DIBOA were present in the roots of triticale and rye. The Hx content o

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22

Hopkinson, Sarah J. "Puccinia graminis f.sp. tritici, race c17 : physiology of uredospore germination and germtube differentiation." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27957.

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Germinating uredospores of race C17 of Puccinia graminis f.sp. tritici form characteristic infection structures (appressorium, infection peg, vesicle, infection hypha) in response to a 1.5 h heat shock at 29° C administered 2 h after germination at 19° C. The proportion of sporelings forming infection structures was augmented by nutrients, n-nonyl alcohol and, an appropriately timed heat shock. The heat shock temperature required to induce maximum differentiation had a very precise optimum which varied slightly for each spore lot. Variations one degree above or below this optimum reduced the p

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23

Greiner, Blake William. "Inoculation and Spread of Dickeya in Potatoes." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/29461.

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Field experiments were conducted in two different growing environments to evaluate the spread and movement of Dickeya dadantii. A procedure to inoculate seed potatoes with Dickeya dadantii was developed to use during this study. Spread of Dickeya dadantii from inoculated potato seed to healthy potato seed during the handling, cutting and planting procedures was not detected at either location. Spread of Dickeya dadantii from inoculated seed to surrounding progeny tubers in the field was documented in both locations. In Florida, 33% of progeny tubers tested positive for Dickeya using PCR, and i

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24

Dhliwayo, Tererayi. "Alternative products in the inhibition of te plant pathogen scleroyinia sclerotiorum on potato production." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/941.

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White mold caused by Sclerotinia sclerotiorum attacks a wide host range of broad-leafed plants which includes potatoes. Current control is limited to the use of chemicals, but biological control has emerged as an eco-friendly alternative. For the study, 19 bacterial strains and 18 fungal strains obtained from soil samples taken from a potato field naturally infested with the pathogen S. sclerotiorum were tested for the effects on S. sclerotiorum mycelium growth and sclerotia viability in vitro. A total of eight bacterial strains and six fungal strains proved to be effective in the inhibition o

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25

Whisson, Desley. "The effect of agricultural techniques on the population dynamics and management of Rattus sordidus in sugarcane crops in North Queensland." Thesis, Queensland University of Technology, 1993. https://eprints.qut.edu.au/105695/1/T%28S%29%2026%20The%20effect%20of%20agricultual%20techniques%20on%20the%20population%20dynamics%20and%20managment%20of%20Rattus%20sordidus%20in%20sugarcane%20crops%20of%20North%20Queensland.pdf.

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Rattus sordidus (canefield rat) is a major pest in north Queensland sugarcane growing areas, causing losses of between $2 and $4 million each year. A further $0.2 to $0.4 million is expended on annual baiting campaigns. This procedure provides only short-term results, is seldom cost-effective and is hazardous to non-target species and the environment. There was a close relationship between the dynamics of R. sordidus populations and the crop cycle. During the 1987/88 crop cycle, breeding occurred over the January- July period and coincided with the period when summergrasses were abundant in

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Lombard, Lorenzo. "Fungal diseases in Eucalyptus and Acacia nurseries in South Africa." Diss., University of Pretoria, 2004. http://hdl.handle.net/2263/24484.

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Studies presented in this dissertation highlight the importance of fungal pathogens in forestry nurseries in South Africa. Both Acacia meamsii seedlings and Eucalyptus hybrid cuttings are shown to be affected by important nursery pathogens. Chapter one presents an evaluation of the potential importance of pathogens to Eucalyptus hedge plants maintained in hydroponics. Hydroponics is a new technology being used in South African forest nurseries, which allows for the rapid establishment of Eucalyptus hedge plants. However, no information is available on pathogens affecting Eucalyptus in hydropon

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Van, der Walt Rachel. "Identifying volatile emissions associated with False Codling Moth infested citrus fruit." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1020056.

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False codling moth is a known pest of economic importance to many cultivated crops in South Africa and Africa south of the Sahara, and is particularly severe on citrus. If the fruit is infested just before harvest the chances of detecting signs of infestation are very low. As a result, the risk of packaging infested fruit and exporting them as healthy fruit is high. It is therefore a priority to develop a post-harvest technique for detection of False codling moth in citrus fruit at different levels of infestation in order to reduce phytosanitary risk. Compounds released and detected were indic

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Freeborough, Michael-John 1971. "A pathogen-derived resistance strategy for the broad-spectrum control of grapevine leafroll-associated virus infection." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53285.

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Thesis (PhD)--University of Stellenbosch, 2003.<br>ENGLISH ABSTRACT: Grapevine leafroll-associated virus-3 is one of ten members of the C/osteroviridae that are known to infect grapevine. Nine of these viruses are associated with grapevine leafroll disease, of which GLRaV-1 and GLRaV-3 are the most important and widespread. Members of the C/osteroviridae are unique amongst the viruses, as it is the only known family whose members encode a heat shock protein 70 kOa homolog (Hsp70h). The Hsp70h is a movement protein (MP) that is required for the active translocation of the virion structur

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Kadango, Tendayi Lovemore. "Farmers' perceptions of insect pests in the Eastern Cape maize-based cropping systems and the effects of crop residue management on insect pest populations." Thesis, University of Fort Hare, 2018. http://hdl.handle.net/10353/6202.

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Maize (Zea mays L.) is one of the most important crops in South Africa that is cultivated for food, feed and as a cash crop. Maize in the Eastern Cape is typically grown for consumption and the Province is one of the least producers owing to small landholdings, poor production conditions and pests. This study investigated: (i) the different maize cropping systems smallholder farmers practice in the Eastern Cape (EC), (ii) the major maize insect pests within the identified cropping systems, (iii) the perceptions of Eastern Cape smallholder maize farmers on the effects of insect pests, and (iv)

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Ferreira, Anton. "Further studies on leaf blackening of proteas." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/2879.

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Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2005.<br>The occurrence of both pre- and postharvest leaf blackening in certain Protea species and cultivars is a problem that severely limits their marketability, vase life and transport options. This research focuses on : (I) The distribution of carbohydrates in inflorescence bearing stems of certain Protea cultivars from harvest, following pulsing with a 10 g.L-1 glucose solution until four weeks postharvest. Stems were held under a variety of postharvest conditions, and (II) The suppression of Protea postharvest leaf blackening

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Mathieu, Danielle. "Effects of temperature and duration of leaf wetness on infection of celery by Septoria apiicola, and cultivar screening for partial resistance." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61198.

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The number of lesions increased with increasing temperatures over the range of wet periods except at 30$ sp circ$C, where their number decreased with increasing wetness duration. Cultivars were evaluated for partial resistance under field and greenhouse conditions. In the field ranking was based on cluster analysis of the standard area under the disease progress curve (SAUDPC) for intervals between sampling dates. In the greenhouse, the cultivars were evaluated on the basis of their response relative to five components of partial resistance: the SAUDPC, mean lesion area (MLA), pycnidial densit

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Luffman, Margie. "Late yellow rust (Pucciniastrum americanum (Farl.) Arth.) of Red raspberry (Rubus idaeus L.)." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61841.

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Odendaal, Deidre. "Orchard and bin treatment with entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) for the control of the codling moth (Cydia pomonella)." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97962.

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Thesis (MSc)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: The codling moth, Cydia pomonella (Lepidoptera: Tortricidae), is the key pest of apples and pears worldwide. The withdrawal of certain fundamental chemicals from codling moth management spray programmes, due to concerns about human, environmental and ecosystem health, has resulted in the search for softer, more environmentally friendly, and safer control measures. Entomopathogenic nematodes (EPNs), naturally occur in the soil, and actively search for hosts. The interest in using EPNs from the families Heterorhabditidae and Stein

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Upadhaya, Arjun. "Plant-Parasitic Nematodes in Field Pea and Potato and their Effect on Plant Growth and Yield." Thesis, North Dakota State University, 2018. https://hdl.handle.net/10365/28875.

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In this study, surveys were conducted in pea and potato fields in North Dakota and Central Minnesota to investigate the incidence and abundance of plant-parasitic nematodes in these fields. Moreover, the effect of the pin nematode, Paratylenchus nanus, on plant growth and yield of six field pea cultivars was determined under greenhouse conditions. Similarly, the influence of lesion nematode, Pratylenchus penetrans, and wilt fungi, Fusarium oxysporum alone and together on growth and yield of potato cultivar ‘Red Norland’, was evaluated in microplots under field conditions. The results indicate

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Birla, Keshav. "Characterization of Cytochrome B from European Field Isolates of Cercospora Beticola with Quinone Outside Inhibitor Resistance." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26553.

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Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is the most important foliar disease of sugar beet worldwide. Control strategies for CLS rely heavily on fungicides including quinone outside inhibitor (QOI) fungicides. We collected 866 C. beticola isolates from sugar beet growing regions in France and Italy and assessed their sensitivity to the QOI fungicide pyraclostrobin. To gain an understanding of the molecular basis of QOI resistance, we cloned the full-length coding region of Cbcytb. All tested QOI-resistant isolates harbored a point mutation in Cbcytb at nu

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Fitzpatrick-Peabody, Erica. "Methodology and Assessment of the Susceptibility of Potato Genotypes to Phytophthora Erythrosetpica Causal Organism of Pink Rot." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/Fitzpatrick-PeabodyER2008.pdf.

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Presello, Daniel A. "Studies on breeding of maize for resistance to ear rots caused by Fusarium spp. and on the occurrence of viruses in maize in eastern Canada." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38260.

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Responses from pedigree selection for resistance to gibberella ear rot were assessed in four maize (Zea mays L.) populations, two selected after inoculation of Fusarium graminearum (Schwabe) macroconidia into the silk channel and two selected after inoculation into developing kernels. Responses were significant in both populations selected for silk resistance and in one of the populations selected for kernel resistance. Selection was more effective in later generations and genetic gains were associated with among-family selection but not with within-family selection. Results obtained here indi

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Constable, Fiona Elizabeth. "Biology and epidemiology of Australian grapevine phytoplasmas." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phc756.pdf.

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Coluzzi, Karen. "Arthropod Scavengers of Colorado Potato Beetle (Leptinotarsa Decemlineata) Cadavers." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/ColuzziK2005.pdf.

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Damavandian, M. R. "Biology of subterranean populations of woolly apple aphid, Eriosoma lanigerum (Hausmann)(Homoptera:Aphididae), in apple orchards." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51638.

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Dissertation (PhD (Agric))--University of Stellenbosch, 2000.<br>ENGLISH ABSTRACT: A study was made of the basic biology of subterranean Eriosoma lanigerum (Hausmann) populations in apple orchards in the Western Cape Province of South Africa. The absence of cornicles and the presence of a vulva could be used to identify 1st instar nymphs and adults respectively. Body length, body width and length of the hind femur are useful for separating 2nd , 3rd and 4th instars. However, separation of 2nd from 3rd instar nymphs was very unreliable. Maximum population growth rate was at 23°C while

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Windell, Nicole Elizabeth. "Leaf blackening and the control thereof in selected Protea species and cultivars." Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20396.

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Thesis (MScAgric)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Leaf blackening, a postharvest disorder which is characterized by a dark brown to black discoloration, is found in most commercially important Protea cut flower species and cultivars. As this disorder is known to increase with storage time, it is a major concern to the South African industry as the use of sea freight is increasingly preferred due to lower transport costs and a more favourable carbon footprint. The cause of leaf blackening has been strongly linked to a carbohydrate stress exerted by the large infloresce

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Amrhein, John Francis. "Modeling the impact of gypsy moth defoliation in individual tree mortality and basal area growth of northern hardwoods of central Pennsylvania." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43380.

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Data for this study were collected by the US Forest Service and the Pennsylvania Bureau of Forestry on nearly 600 plots in central Pennsylvania. Tree and stand characteristics recorded between 1978 and 1985 include estimates of percent defoliation on individual trees. Logistic regression using maximum likelihood estimation was employed to model individual-tree mortality of 15 species in central Pennsylvania that had been defoliated by the gypsy moth. Defoliation was estimated to the nearest ten percent for individual trees. Other variables used for prediction included stand basal area and an i

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McConnell, Steven P. "Effects of gypsy moth defoliation on acorn production and viability, litterfall, and litter layer depth and biomass in north-central Virginia and western Maryland." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45883.

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<p>The effects of gypsy moth defoliation on acorn production (the seed source for oak regeneration), and the forest floor regeneration environment were investigated. Parameters measured included: acorn quantity, weight, development, and viability; litterfall; and forest floor depth and biomass. Nineteen plots in north-central Virginia and western Maryland on which trees suffered heavy, moderate, or no defoliation were monitored over a two-year period.</p><br>Master of Science

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Burgess, Kimberly. "Analysis of Deoxynivalenol and Deoxynivalenol-3-glucoside in Wheat." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26454.

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Deoxynivalenol (DON), a mycotoxin produced in cereal grains infected by Fusarium Head Blight produced by Fusarium graminearium and Deoxynivalenol-3-?-D-glucopyranoside (DON-3G), were studied during processing using LC-MS-MS and GC. DON reduced significantly (P<0.05) 61.8% during milling into flour. Therefore, DON was concentrated mostly in the bran and germ. DON increased 40.8% during the fermentation stage of baking. DON increased in dough more than flour and mixed dough. Milling reduced by 23.7% but fermentation did not. But bread was significantly lower in DON-3G at 0.15 ppm than flour an

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Dennis, Jeremy Ian. "Chocolate spot of faba beans in South Australia." Title page, contents and summary only, 1991. http://web4.library.adelaide.edu.au/theses/09A/09ad411pdf.pdf.

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Bibliography: leaves 81-100. Entry of inoculum into a crop and disease development in the crop cannot be prevented because spores are airborne and there is a lack of highly resistant varieties. This makes complete control of chocolate spot unlikely. It should however, be possible to improve current levels of disease control through the integration of the factors identified in the study.

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Zondo, Patience Thembelihle. "Assessment of inoculation techniques to evalute apple resistance to Phytophthora cactorum." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52141.

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Thesis (MSc)--University of Stellenbosch, 2001.<br>ENGLISH ABSTRACT: Phytophthora cactorum (Lebert & Cohn) Schrot. is the primary cause of crown, collar and root rot diseases of apple (Malus domestica Borkh.) trees worldwide. This pathogen is most destructive in commercial apple orchards under waterlogged soil conditions and has recently been identified as causing serious disease in some South African apple orchards. Crown, collar and root diseases are difficult to control because of their unpredictability and catastrophic nature. The use of resistant cultivars and rootstocks is economic

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Robbs, Steven Lynn 1961. "Genotypic variation in susceptibility of Pisum sativum to crown gall and characterization of one cultivar of pea with reduced susceptibility to crown gall." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277008.

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Thirty-four cultivars of pea (Pisum sativum) were assayed for tumorigenesis after inoculation with Agrobacterium tumefaciens strain B6. The response of the 34 cultivars fell into 3 significantly different groups based on tumor weights: high, medium, and low susceptibility. The least susceptible cultivar, Sweet Snap, also formed the smallest tumors in comparison to 5 other cultivars when inoculated with 5 other strains of Agrobacterium. Preliminary experiments indicate that neither chemotaxis, binding, vir-gene induction, nor T-DNA expression are limiting factors in Sweet Snap's reduced suscept

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Cozens, Russel David. "Insect and disease risk factors in established interior spruce plantations." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24426.

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Forest insects and diseases active in immature interior spruce stands in the central interior of British Columbia and their possible implications in forest management practices have been surveyed. Collection records, spanning the period 1949 to 1982, from the Forest Insect and Disease Survey of the Canadian Forestry Service were reviewed for the Prince George Timber Supply Area and the pest incidence in immature interior spruce stands summarized. Twenty-two plantations, established between 1963 and 1973, were surveyed to determine the relative incidence of the major insect and pathogen pests

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"Health, Diseases, and Pests." College of Agriculture, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/295623.

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Cheng, Yuan-Wei, and 鄭元瑋. "Image Recognition Technology of Rice Diseases and Insect Pests." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7bvuz6.

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碩士<br>國立中正大學<br>電機工程研究所<br>104<br>Rice is one of the most important agricultural products in ROC . In order to ensure the productivity of rice , the prevention and treatment of disease and pest is an important issue . Nowadays , the mainstream of rice cultivation is high density planting , witch make us hard to discover disease and pest of rice at the very first time . As a result , those plants with illness may infect other plants , and it will affect the total yield of rice . Therefore we design a recognition system based on image processing technology helping users recognize illness easily

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