EPWS 310 EXAM 3, Fall 1999

1. (14 pts) Briefly define the following terms:

autoecious

 

perithecium

 

capsid

 

pycnidium

 

cleistothecium

 

sclerotium

 

nonpersistent

 

2. (8 pts) Give the genus of one fungus that causes vascular wilt. Describe how the pathogen overwinters and the mechanism by which it causes disease.

 

 

 

 

 

 

 

 

 

3. (8 pts) Describe how man is a vector of many plant viruses.

 

 

 

 

 

 

 

 

4. (10 pts) What control measures work against fungal post harvest diseases? Give examples of three fungi that cause post harvest diseases.

 

 

 

 

 

 

 

 

 

 

5. (10 pts) Chose one of the following diseases (apple scab or brown rot) and answer the questions below about its disease cycle. For 5 extra credit points, answer both questions.

a) What is the overwintering structure?

 

b) What serves as primary inoculum

 

c) What serves as secondary inoculum?

 

d) What are two mechanisms of control?

 

e) What pathogen causes the disease?

 

 

6. (8 pts) Describe how a (+) ssRNA virus replicates in a cell

 

 

 

 

 

 

 

 

7. (10 pts) Give an example of a fungal disease where crop rotation will work well and one where it is of limited value and explain your answers.

 

 

 

 

 

 

 

 

8. (8 pts) Why don't all leafhoppers transmit beet curly top geminivirus?

 

 

 

 

 

9. (14 pts) Diagram the life cycle/disease cycle of stem rust of wheat. Show the nuclear state of all stages and which host it is on.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWER ONE OF THE FOLLOWING QUESTIONS

10. (10 pts) What are four methods to detect plant viruses and what part(s) of the virus do they detect?

 

 

 

 

 

 

 

 

10. (10 pts) What information is needed before choosing a control strategy for plant viruses? Give two examples of how the information could be used.