Thesis (Ph. D.)--University of Michigan, 1930. / Cover title. "Reprinted from the American journal of botany, vol. XVIII, no. 1 ... January, 1931." "Literature cited": p. 76-78.

Ergot, caused by the fungal pathogen Claviceps purpurea (Fr.) Tul., attacks the floral organs of many grassy species resulting in sclerotia production rather than grain. Infection causes reduced yields, downgrading, and poisoning if consumed by humans or animals. Few recent studies have been conducted on ergot in wheat (Triticum spp.), and prevention is the only means of control. The objectives of this study were to determine if western Canadian spring wheat differed in reaction to infection with C. purpurea and if levels of inoculum would affect disease intensity in a field setting. Three variables were measured for the field experiments to determine disease reaction, including percent sclerotia by weight, number of sclerotia per spike, and weight per sclerotium. In the first experiment, nine wheat cultivars were tested using three inoculum levels. No significant differences were detected among inoculum levels. In the second and third experiments, ninety-two cultivars were studied in field and controlled conditions. Honeydew production, sclerotial size, and the percent of florets aborted were added as variables in the growth chamber experiment. Pearson correlations were calculated using cultivar means for the field and controlled environments. Results indicate that there are differences in disease reaction among cultivars and market classes, but these differences varied depending on the evaluation method used. In the field, CWAD wheat had the smallest sclerotia, but had more per spike compared to the CWRS and CWES market classes. There were no significant differences among these market classes for percent sclerotia by weight. In the growth chamber, CWAD wheat generally had the lowest ergot infection levels. When comparing the market classes within T. aestivum (CWRS, CPS, and CWES), there were no significant differences except for honeydew production. The correlation between environments was not significant for any of the variables, suggesting alternate resistance mechanism expression. In the field, reduced infection may be due to an escape mechanism, while artificial inoculation in a controlled environment may detect a physiological resistance mechanism. However, a group of cultivars with Grandin parentage showed promising results in both environments, and might confer resistance that could be integrated into disease resistance breeding programs.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-15T14:34:52Z No. of bitstreams: 1 PGCA15MA209.pdf: 754313 bytes, checksum: d222ad27deddfb1802f4b7162c86c21e (MD5) / Made available in DSpace on 2018-03-15T14:34:52Z (GMT). No. of bitstreams: 1 PGCA15MA209.pdf: 754313 bytes, checksum: d222ad27deddfb1802f4b7162c86c21e (MD5) Previous issue date: 2015-12-03 / FUMDES / Ergotism is a disease caused by ingestion of sclerotia called ergot, which contains alkaloids that act on adrenergic, dopaminergic and serotonergic causing direct effect on blood vessels, smooth muscle and central and autonomic nervous system. The present study describes epidemiological data, clinical signs and lesions of a cattle disease characterized by hyperthermia, tachycardia, tachypnea and injuries in the coronary band of the hoof. Initially cause was attributed to the fungus Claviceps purpurea. Between 2000 and 2014 were reported 13 outbreaks, three distérmica form, three nervous form and seven gangrenous form. However, in five of the seven outbreaks of the gangrenous form, in places where animals grazed there was loads of inflorescences of smut grass (Sporobolus indicus) contaminated by a blackened fungus, classified as Bipolaris australis. The disease was reproduced experimentally by administration of inflorescences of smut grass contaminated by B. australis. For five cattle were administered daily doses of 0.1 g/kg, 0.2 g/kg, 0.2 g/Kg, 0.26 g/kg and 0.34 g/kg for 4, 7, 9, 30 and 30 days respectively. After three to seven days of eating contaminated inflorescences four cattle had diarrhea, tachycardia, tachypnea and intermittent hyperthermia. These clinical signs coincided with warmer days and warmer temperatures of the day. An animal showed hyperemia in the coronary band of the hoof and loss of the tail end of the hair. According to results of this study in cattle, can prove that smut grass (Sporobolus indicus) contaminated by B. australis can cause hyperthermia, tachycardia, tachypnea, injuries in the coronary band of the hoof and loss of the tail end of the hair / Ergotismo é uma enfermidade causada pela ingestão de escleródios chamados de ergot, que contém alcalóides que atuam em receptores adrenérgicos, dopaminérgicos e seratoninérgicos causando efeito direto em vasos sanguíneos, musculatura lisa e sistema nervoso central e autônomo. Descrevem-se dados epidemiológicos, sinais clínicos e lesões de uma enfermidade de bovinos caracterizada por hipertermia, taquicardia, taquipneia e ulcerações na coroa do casco de bovinos. Inicialmente a etiologia foi atribuída ao fungo Claviceps purpurea. Entre 2000 e 2014 foram descritos 13 surtos, três da forma distérmica, três da forma nervosa e sete da forma gangrenosa. Porém, em cinco destes sete surtos, nos locais onde esses animais pastoreavam havia grande quantidade de inflorescências de Sporobolus indicus conhecido como “capim-mourão”, contaminadas por um fungo com coloração enegrecida, identificado como Bipolaris australis. A enfermidade foi reproduzida experimentalmente em cinco bovinos com a administração destas inflorescências. Os bovinos em experimentação receberam respectivamente doses diárias de 0,1g/kg, 0,2g/kg, 0,2g/kg, 0,26g/kg e 0,34g/kg por um período de 4, 7, 9, 30 e 30 dias. Após três a sete dias de ingestão das inflorescências contaminadas, quatro dos cinco animais apresentaram diarreia e manifestaram taquicardia, taquipneia e hipertermia em algum período durante a ingestão. Estes sinais coincidiram com os dias mais quentes deste período. Um animal manifestou hiperemia na coroa do casco e perda de pêlos da extremidade da cauda. Baseado na reprodução experimental é possível afirmar que o capim Sporobolus indicus contaminado pelo fungo Bipolaris australis é capaz de causar hipertermia, taquicardia, taquipneia, hiperemia na coroa do casco e perda de pêlos da extremidade da cauda

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