EPWS 310 EXAM 2, Fall 2007
1. (2 pts each) Define the following terms:
2. (9 pts) Which classes of fungi that we discussed in class produce zoospores? What environmental conditions favor diseases caused by these fungi? What methods can be used to control all these fungi?
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 peach leaf curl and club root of crucifers. (Extra credit 2 pts each, give the genus of the causal agent).
5. (6 pts) List and explain 4 ways that Oomycetes differ from Zygomycetes.
6. (6 pts) Both Rhizopus soft rot and damping off are problems primarily in man-made environments. What are the environmental conditions that promote each disease, what spore types are most responsible for spread, and how can each be controlled?
7. (12 pts) Compare the dissemination methods, primary inoculum, secondary inoculum, overseasoning methods and forms, and control of late blight of potato and Phytophthora ramorum causing sudden oak death.
8. ( 4 pts) Compare indirect and direct germination of Oomycetes? How do water and temperature influence the type of germination?
9. You have been called to the field to look at mildew on grapes in Deming.
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 Deming?
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) (18 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 downy mildew of grape. What is the causal agent (genus and species)? How can the disease be controlled?