Dissertation
Epidemiology and management of sweet cherry powdery milew in Washington nurseries
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/118423
Abstract
Powdery mildew of sweet cherry caused by Podosphaera prunicola is a major problem in cherry nursery production. Morphological studies, molecular studies and cross inoculation studies have shown that chokecherry and sweet cherry are infected by two different Podosphaera species, and the chokecherry powdery mildew fungus was identified as Podosphaera tridactyla based on the descriptions of Braun and Cook (2012). Epidemiological studies that were conducted in the sweet cherry nursery located in Quincy WA, have indicated that the initial inoculum might be originating from the nearby cherry orchards. Cherry rootstock had shown chasmothecia on the stem (with 2-5% viable ascospores) but the rootstock did not develop powdery mildew signs. Powdery mildew infections in the nursery start after 1 month of powdery mildew epidemic in the nearby orchards. Spore concentration in the nurseries was monitored using Rotary impaction spore traps and P.prunicola spores were detected in the nursery air one month prior to the development of powdery mildew signs in the nursery. Disease ratings have shown that the incidence of powdery mildew increases from late July until August. There was a positive correlation between the spore concentration, relative humidity and disease severity.
The trees in the storage were loaded with chasmothecia along the stem; the viability of the chasmothecia was high in the month of January and went down by the end of May. These cherry trees neither developed any flag shoot nor developed the signs of powdery mildew. Cherry leaves that were collected from the nursery floor showed the highest viability in the beginning of the year but the viability went down by June, and the chasmothecia with viable ascospores did not develop infections on either the detached leaf or the attached leaf assay. Electrolyzed oxidized water was found to be effective in reducing the disease severity and number of chasmothecia formation (p<0.05), whereas the bio fungicides were not effective in controlling powdery mildew in sweet cherry.
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Details
- Title
- Epidemiology and management of sweet cherry powdery milew in Washington nurseries
- Creators
- Swarnalatha Moparthi
- Contributors
- Gary G Grove (Advisor)Scot H Hulbert (Committee Member)Weidong Chen (Committee Member)Dennis A Johnson (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Plant Pathology
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 167
- Identifiers
- 99900581720901842
- Language
- English
- Resource Type
- Dissertation