EPWS 310 EXAM 2, Fall 2010
1. (2 pts each) Define the following terms:
2. (9 pts) A. What environmental conditions favor damping off and why?
B. How can damping off be controlled?
C. List three organisms (genera) that cause damping off.
3. (3 pts) Compare control of slime mold on turf with sooty mold on melon.
4. (12 pts) Compare the primary inoculum, dissemination mechanism, secondary inoculum, overseasoning place and form, and control of downy mildew of grape and club root of crucifers. (Extra credit 2 pts each, give the genus of the causal agent).
5. (6 pts) List and explain 3 ways that Oomycetes differ from Chytridiomycetes.
6. (4 pts) A. What environmental conditions favor Phytophthora root rot of chile?
B. What are two methods to control the disease?
7. (16 pts) Compare the disease symptoms, dissemination methods, primary inoculum, secondary inoculum, overseasoning methods and forms, and control of Rhizopus on fruit and Phytophthora ramorum causing sudden oak death.
8. ( 6 pts) How do water and temperature influence the germination of sporangia and dissemination of Phytophthora infestans which causes late blight of potato?
9. You have been called to the field to look at mildew on grapes in Santa Fe.
a) (4 pts) What are two ways that you can determine if you are looking at powdery mildew or downy mildew and which characters would you expect for each fungal type? Which of these two diseases would you more expect to find in Santa Fe?
b) (4 pts) How could you microscopically differentiate among the genera of powdery mildew to determine which one is present? How about the genera of downy mildew?
c) (16 pts) You decide that it is powdery mildew. You need to explain the disease to the grower. Draw the disease cycle of powdery mildew, indicating what serves as primary inoculum, secondary inoculum, how it is disseminated, and how it overwinters. Include the sexual gametes and show where plasmogamy, karyogamy, and meiosis occur.
d) (4 pts) The grower wants to know if changing their irrigation practices will help control the disease. Do you answer yes or no, and what control measures will you advise?
(8 pts extra credit) Outline the disease/life cycle of peach leaf curl. What is the genus of the causal agent ? How can the disease be controlled?