Thesis (Ph. D.)--University of Illinois, 1916. / Vita. "Reprinted from the American journal of botany, 4 ... October, 1917." "Literature cited": p. 474-475.

Thesis (Ph. D.)--University of Illinois, 1916. / Vita. "Reprinted from the American journal of botany, 4 ... October, 1917." "Literature cited": p. 474-475.

Thesis (Ph. D.)--Colorado State University, 2004. / Includes bibliographical references.

Cowpea (Vigna unguiculata (L.) Walp is an indigenous food legume in Africa, which has great production potential, especially in areas with low agricultural resources. During surveys of cowpea fields in southern Africa, a new foliar disease was recorded. Alternaria cassiae Juriar&Khan was consistently isolated from diseased plant material. Pathogenicity was confirmed using Koch's Postulates. The effect of different culture media, temperature, light and wounding on the growth and sporulation of the fungus was studied. A. cassiae grew well and produced conidia abundantly when maintained on V8-agar at 25°C in a 12h UV-light/12h dark cycle. Sporulation was further enhanced by wounding the cultures. The pre-penetration and infection process of A. cassiae on cowpea leaves was studied by light and scanning electron microscopy. Conidia germinated within 2-3h post inoculation (hpi), forming multiple germ-tubes randomly that grew in any direction across the leaf surface. By 8hpi terminal or intercalary appressoria were formed above epidermal cells or over stomata. Occasionally germ-tubes entered stomata, without the formation of appressoria. Penetration of the plant surface, whether directly through the epidermis or indirectly through stomata was observed 72hpi. Following penetration bulbous primary hyphae were observed within the sub-stomatal cavities, secondary hyphae developed from the primary hyphae and grew within the intercellular spaces penetrating epidermis and mesophyll cells. A. cassiae is a necrotrophic fungus as the infection process is characterised by a destructive necrotrophic phase where plant cells became necrotic even prior to fungal penetration. Conidial morphology, types and development of the fungus were studied in vitro on different culture media and in vivo on cowpea leaves. A. cassiae produced a mixed population of three conidial types. Conidia were formed singly or in chains of 2-4 conidia. Conidia with long, filiform beaks and conidia with shorter beaks, converted into secondary conidiophores were more frequently produced than mature, beakless conidia on all the media, except on potato dextrose agar. Conidial body and beak sizes were variable when measured in culture and on cowpea leaves. Conidia produced in culture were larger, than those produced in vivo. Conidiophores emerged directly through the epidermis or stomata or were formed when hyphae growing on the leaf surface differentiated into conidiophores. Smooth, bud-like conidial initials were produced at the apex of conidiophores. Conidia matured and became elliptical to obvate and densely verrucose. Once a mature conidium had detached, a small pore was visible at the apex of the conidiophore. A. cassiae was shown to be seed-borne in cowpea. Six fungicides i.e. Benomyl, bitertanol, captab, mancozeb, propiconazole and triforine were evaluated for their efficacy in reducing mycelial growth of A. cassiae in vitro. All fungicides except benomyl proved to be effective. Cowpea seeds were artificially inoculated with A. cassiae and treated with all the fungicides except benomyl. Percentage germination and infection was determined in vitro. Percentage emergence, disease incidence, root and shoot lengths and abnormalities were determined in greenhouse trials. Only bitertanol at l.5x the recommended dosage significantly reduced percentage germination. All treatments except triforine l.0x and l.5x significantly decreased the percentage infection of artificially inoculated seeds. None of the treatments except bitertanol l.5x showed a difference in shoot and root length when compared to the control. Captab l.5x the recommended rate proved to be the best treatment over all. / Dissertation (MSc (Botany))--University of Pretoria, 2006. / Plant Science / unrestricted

Alternaria tagetica is capable of producing phytotoxins in vitro. One toxin was identified as zinniol with: bioassays; thin-layer and gas chromatography; staining properties; ultraviolet and mass spectrometry, and nuclear magnetic resonance spectroscopy. The identity of the other toxin(s) has not been established. Symptoms similar to those caused by infection developed on detached marigold leaves treated with either of the toxins or synthetic zinniol. The toxins are not host selective. The distribution of zinniol among Alternaria species was studied. Thirty-one isolates of 10 pathogenic Alternaria spp. were tested for their ability to produce zinniol. Analyses were performed by gas-liquid and thin-layer chromatography. Of the seven pathogenic large-spored, long-beaked species tested A. carthami, A. macrospora, A. porri, A. solani, A. tagetica, and an unnamed isolate from Phaseolus vulgaris pods produced zinniol. A. brassicae, a non-pathogenic isolate of A. zinniae, and three pathogenic species lacking large-spores and long-beaks (A. alternata, A. citri, and A. raphani) did not produce zinniol. The quantity of zinniol produced varied greatly among species, among isolates of a single species, and between trials of the same isolate. All hosts of the Alternaria spp. tested were sensitive to zinniol at 50 to 200 micrograms/ml. Conservation of zinniol in pathogenic large-spored Alternaria spp. may be indicative of its importance in pathogenesis. Light affects the behavior of Alternaria tagetica in vitro and in vivo. In vitro zinniol production occurred only during active fungus growth in the light; in the dark zinniol production occurred primarily after growth stopped. In all filtrates, the quantity of zinniol rapidly declined once zinniol production ceased. Fungus growth was inhibited by both continuous and alternating light and sporulation occurred on one of three test media and only under alternating light. More lesions were produced on inoculated plants kept in dark humidity chambers than in illuminated humidity chambers. Low illuminance was more conducive to lesion development than high illuminance and more lesions developed on plants exposed to low illuminance for 48 hr prior to inoculation than on those exposed to high illuminance. The limitations of studies in which the effect of light has been overlooked are discussed.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of the present work was to evaluate the physiologic quality of carrot seeds, cilantro and parsley, associated with Alternaria alternata and A. dauci under two inoculation methods, conidial suspension and restriction hidric. The isolated of A. dauci and A. alternata were obtained, respectively, of carrot plants with symptom of the disease and of seeds of each one of the species, submitted to an initial test of sanity (Blotter Test). The inoculation treatments for suspension consisted in: testifies (distilled water and sterilized), conidial suspension of A. alternata, conidial suspension of A. dauci and conidial suspension of both species (A. alternata + A. dauci). Para restriction hidric: PDA + manitol (testifies); PDA + manitol + A. alternata; PDA + manitol + A. dauci; PDA + manitol + A.alternata + A.dauci. The physiologic quality of the seeds was evaluated by a group of tests accomplished in controlled conditions of laboratory and green house. The quality of carrot seeds, cilantro and parsley is influence by the association with it would Alternaria alternata and A. dauci. The use of the inoculation of seeds through the conidial suspension is efficient in the contamination of carrot seeds for A. alternata and A. dauci. The use of the manitol, as a restritor hidric, is effective for the obtaining of seeds infected by A. dauci in the culture of the parsley. Already for cilantro seeds, both methods demonstrated satisfactory levels of infection. / O objetivo do presente trabalho foi avaliar a qualidade fisiológica de sementes de cenoura, coentro e salsa, associadas com Alternaria alternata e A. dauci, sob dois métodos de inoculação, suspensão de conídios e restrição hídrica. Os isolados de A. dauci e A. alternata foram obtidos, respectivamente, de plantas de cenoura com sintomas da doença e de sementes de cada uma das espécies, submetidas a um teste inicial de sanidade (Blotter Test). Os tratamentos de inoculação para suspensão consistiram em: tratamento testemunha (água destilada e esterilizada), suspensão de conídios de A. alternata, suspensão de conídios de A. dauci e suspensão de conídios de ambas as espécies (A. alternata + A. dauci). Para restrição hídrica: BDA + manitol (tratamento testemunha); BDA + manitol + A. alternata; BDA + manitol + A. dauci; BDA + manitol + A.alternata + A.dauci. A qualidade fisiológica das sementes foi avaliada por um conjunto de testes realizados em condições controladas de laboratório e em casa de vegetação. A qualidade das sementes de cenoura, coentro e salsa é prejudicada pela associação com Alternaria alternata e A. dauci. A utilização da inoculação de sementes através da suspensão de conídios é eficiente na contaminação de sementes de cenoura por A. alternata e A. dauci. A utilização do manitol, como um restritor hídrico, é eficaz para a obtenção de sementes infectadas por A. dauci na cultura da salsa. Para sementes de coentro, ambos os métodos demonstram níveis satisfatórios de infecção.

Orientador: Kurozawa Chukichi / Resumo: O presente trabalho visou verificar a ação "in vitro" e "in vivo" de alguns fungicidas e do indutor de resistência acibenzolar-S-methyl (BTH) no controle da pinta preta do tomateiro e seus reflexos na produção. A ação "in vitro" de fungicidas, nas concentrações de 0, 1, 10 e 100 μgmL-1 do ingrediente ativo, foi verificada com base no crescimento micelial, germinação de conídios e efeito anti-esporulante sobre A. solani. Em condições de casa de vegetação foram estudadas as ações: preventiva, residual e curativa de fungicidas em cultivares com diferentes níveis de resistência a pinta preta. Em experimentos de campo, realizados nos municípios paulistas de Sumaré (1999), Socorro (2000) e Bragança Paulista (2000 e 2001), foi avaliada a ação de diferentes grupos fungicidas e acibenzolar-S-methyl (isolado, em mistura com fungicidas e em programas de aplicação) sobre: a severidade da doença (folíolos e hastes); redução de área foliar; incidência de frutos sadios; doentes e danificados pelo sol; massa fresca de frutos sadios, produção em kilos por 10 plantas e porcentagem de frutos grandes, médios e pequenos (Bragança Paulista, 2001). Todos os fungicidas apresentaram ação positiva e diferenciada para todos os parâmetros avaliados, em função das características inerentes de cada princípio ativo. Os maiores potenciais de controle foram verificados para os fungicidas com maior especificidade e ação sistêmica... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The aim of this study was to verify the "in-vitro" and in-vivo effectiveness of various fungicides and plant activator acibenzolar-S-methyl (BTH) in the control of tomato early blight and its effects on yield. The in-vitro effect of the fungicides, in the concentrations 0, 1, 10 and 100 μgmL-1 of the active ingredient, was assessed based on mycelial growth, conidial germination, and the antisporulating effect on A. solani. The various groups of fungicides were studied to compare their preventative, residual and curative efficacy, in greenhouse environment. Field tests were conducted in the state of São Paulo, Brazil, in the countries of Sumaré (1999), Socorro (2000) and Bragança Paulista (2000 and 2001), to compare the effect of various fungicide groups and acibenzolar-S-methyl (alone, mixed with the fungicides, or applied in conjunction with fungicidal treatments) on various parameters: the severity of the disease (leaflets and stems); percentage of leaf drop; relative numbers of healthy fruit as compared to diseased or sun-damaged fruit; yield in kg per 10 plants; and the relative percentages of large, medium and small-sized fruits (Bragança Paulista, 2001). All the fungicides presented a positive effect on all of the parameters evaluated, consistent with the active ingredients of each. The greatest efficacies of control were shown by systemic, more-specific fungicides. In regard to mycelial growth and conidial germination, the greatest inhibition percentages were obtained with metconazole, tebuconazole, difenoconazole, iprodione, cyprodinil, procymidone, prochloraz, fluazinam and pyrimethanil. The fungicides kresoxim methyl, azoxystrobin, pyraclostrobin+methiram, fenamidone+chlorothalonil and famoxadone+mancozeb presented an intermediate degree of inhibition on the mycelial growth and complete inhibition of conidial germination at concentrations of 1 μgmL-1 and above... (Complete abstract, click electronic address below). / Mestre

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