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Towards Development of a Disease Risk Model for Pea Root Rot Disease
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- Author / Creator
- Safarieskandari, Samira
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Pea root rot is one of the major diseases of field pea (Pisum sativum) in the Canadian prairies. Field avoidance is one possible approach for reducing yield loss caused by root rot. Current research aimed to investigate the possibility of developing a model to predict root rot. Surveys were conducted in Alberta pea fields and pathogens were isolated and identified by PCR from infected roots. The three main pathogens identified were Fusarium avenaceum, F. solani f. sp. pisi and Aphanomyces euteiches. Greenhouse tests showed that these were the most aggressive species, and F. avenaceum and F. solani f. sp. pisi had high varied from weakly to highly aggressive. A soil greenhouse bioassay and a quantitative PCR (qPCR) test of soil were compared for predicting root rot. First, the inoculum dose-disease response relationship was determined for F. avenaceum and F. solani f. sp. pisi, as this is the initial step to develop a predictive model. Analyses indicated a positive linear correlation between Fusarium spp. inoculum dose, disease severity and recovered DNA quantity. The ability of greenhouse bioassays to predict field disease severity was tested, and the results showed a significant positive correlation, which indicated the bioassay method is likely to provide reliable results for disease prediction. The incidence of pathogen DNA in soil was also a good predictor of the incidence of pathogens in roots, but was dependent on year, and the amount of pathogen DNA quantified in soils was low compared with observed disease severity. To develop a preliminary model, 260 samples were collected during the 2016 and 2017 growing seasons prior to planting pea in early April from commercial pea fields across Alberta. The DNA quantity, temperature and rainfall data were used to develop a regression model to assess the potential for disease prediction prior to planting. Temperature, rainfall and DNA quantity of F. solani f. sp. pisi and A. euteiches had a significant effect on root rot development. DNA quantity of F. solani f. sp. pisi, F. avenaceum and A. euteiches explained 5.8, 5.1 and 6.0%, respectively of the disease severity. Improving the model requires finding improved DNA extraction methods for soil with high clay content and validation across a wide range of cultural practices and environments.
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- Subjects / Keywords
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- Graduation date
- Fall 2019
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.