EPWS 310 PLANT PATHOLOGY EXAM 2, Fall 2006
1. (2 pts each) Define the following:
2. a)(3 pts) What environmental conditions favor damping off and why?
b) (2.5 pts) How can damping off be controlled?
c) (4.5 pts) List three organisms (genera) that can cause damping off.
3. a) ( 3 pts) What environmental conditions favor club root of crucifers and why?
b) (3 pts) How and where does the organism overwinter?
c) (3 pts) What are two methods to control the disease?
4. (10 pts) Make a flow chart or simple dichotomous key to differentiate the Plasmodiophoromycetes, Chytridiomycetes, Oomycetes, Zygomycetes, and Ascomycetes. Explain what characters differentiate the classes at each junction or step.
5. (14 pts) Compare the organisms and diseases, dissemination, primary inoculum, secondary inoculum, overseasoning, and control of powdery mildews and downy mildews.
6. (8 pts) What is the nuclear state of Oomycete and Ascomycete mycelia and when do plasmogamy, karyogamy, and meiosis occur?
7. (12 pts) Compare the disease, primary inoculum, dissemination, secondary inoculum, overseasoning, and control of Rhizopus infection of fruit with Phytophthora capsici infecting chile.
8. (6 pts) How do water and temperature influence the germination of sporangia and dissemination of late blight of potato?
9. (3 pts) What are 2 types of diseases induced by Olpidium (Chytridiomycete) infection?
10. (10 pts) Sudden oak death, which we covered in the case study, is a tremendous problem in northern California causing dieback and death to many woody perennials, both native trees and ornamentals. How would you expect the pathogen to overwinter? What control strategies would you suggest? Would you expect the disease to do well in Las Cruces?
(10 pts extra credit) Outline the disease cycle of peach leaf curl. What is the genus of the causal agent? How can the disease be controlled?