Date of Award:
5-1966
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Plants, Soils, and Climate
Department name when degree awarded
Plant Pathology
Committee Chair(s)
Orson S. Cannon
Committee
Orson S. Cannon
Committee
Bryce N. Wadley
Abstract
Downy mildew of alfalfa (caused by Peronospora trifoliorum d By) was found to be epidemic on susceptible varieties of alfalfa in northern Utah during 1965. The increase in the amount of downy mildew present was due to the more abundant rainfall and cooler than normal temperatures which prevailed during the summer months of 1965 (Environmental Science Services Administration, 1965). The author observed many of the highly susceptible varieties of alfalfa had 25-30 percent of their leaflets infected with the downy mildew fungus. Because of the epidemic developments of alfalfa downy mildew, an investigation was undertaken to explore the following questions in its life cycle:
1. What is the mode of penetration of the germinating Peronospora trifoliorum sporangiospores into epidermal cells of the leaves of alfalfa plants? What is the effect of varying the temperature on the mode of penetration?
2. What is the effect of time of day on production and germination of spores?
3. What effect does temperature have on sporangiospore germination and germ tube growth.
4. Does light play a role in the germination of spores and in the growth of the germ tube?
Recommended Citation
Waite, Sheldon B., "Studies of Peronspora trifoliorum deBary Cause of Downy Mildew of Alfalfa" (1966). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 9133.
https://digitalcommons.usu.edu/etd/9133
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