Thesis
Seasonal development and dispersal of Chasmothecia of Erysiphe necator and Podosphaera clandestina, causal agents of the powdery mildews of viniferous grapes and sweet cherries
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/103016
Abstract
The powdery mildews of grape (Vitis vinifera L.) and sweet cherry (Prunus avium L.), which are caused by Erysiphe necator and Podosphaera clandestina, respectively, are the most problematic diseases of their respective hosts in eastern Washington. Chasmothecia are the only known form of perennation for both pathogens. A 2-yr study was conducted to determine the temporal formation of chasmothecia on infected foliage as well as primary and seasonal modes of dispersal. Chasmothecia development on leaves was tracked from mid-Jul through mid-Oct. Chasmothecia of P. clandestina were first formed shortly after harvest in early Jul and those of E. necator in late Aug or mid-Sep. Chasmothecia numbers of both pathogens on foliage peaked near leaf fall in October. Wooden posts 3 m in height equipped with glass slides (orientated vertically and horizontally) coated with silicon grease and filter paper cones were positioned around the periphery of the vineyard and orchard to study dispersal of chasmothecia by air currents. Peak dispersal for both types of chasmothecia occurred in Oct and was significantly correlated with precipitation and wind speed. The viability of ascocarps ranged from 38% to 92% for E. necator and from 56% to 96% for P. clandestina. Chasmothecia appear to be loosened by precipitation and then dispersed by rain splash or air currents. In eastern Washington, an area characterized by sustained periods of high winds, dispersal by the latter mechanism may be epidemiologically significant to both diseases by survival rates improvements and further distributions.
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Details
- Title
- Seasonal development and dispersal of Chasmothecia of Erysiphe necator and Podosphaera clandestina, causal agents of the powdery mildews of viniferous grapes and sweet cherries
- Creators
- Jingying Zhang
- Contributors
- Gary G. Grove (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525023101842
- Language
- English
- Resource Type
- Thesis