Name   ______________________

 

            EPWS 310    EXAM 3    Fall 2009                      

 

1.    (2 pts each) Briefly define the following terms:

 

chlamydospore

 

 

semipersistent foregut-borne

 

 

ringspot

 

 

perithecium

 

 

dikaryon

 

 

clamp connection

 

 

viroid

 

 

microcyclic

 

 

 

2.    (8 pts) List the genus of an fungus that causes leaf spots.  Describe how the pathogen overwinters, how it is disseminated, and how the disease can be managed.

 

 

 

 

 

 

 

3.    4pts) Give an example of a fungal disease where cold storage and good ventilation  works well to limit disease and another example where it does not work well and explain your answers.

 

4.     (7 pts) List the genus of an Ascomycete fungus that causes root rot.  Describe how the pathogen overwinters, how it is disseminated, and how the disease can be managed.

 

 

 

 

 

 

 

5.    (8 pts) List the steps for a +ssRNA plant virus to replicate beginning with entry into a cell and concluding with exit from a cell.  What steps differ if the virus is (-) ssRNA?

 

 

 

 

 

 

 

 

 

 

 

 

6.    (8 pts) Explain the life cycle of corn smut caused by Ustilago maidis.  Include how it overwinters, the spore type(s) it produces, how it infects, and how it causes disease.

 

 

 

 

 

 

 

 

7.    (15 pts) For 3 viruses in different groups, explain what types of symptoms they cause, what hosts they typically infect, how they are transmitted (vector and persistence), and how they can be controlled.

 

 

 

 

 

 

 

 

 

8.    (11 pts) In your job for Syngenta you are asked to develop a biocontrol agent (fungal or bacterial) to control wheat rust.  Explain which spore stage you will target and why.  Diagram the disease/life cycle of the rust, indicating which spore stages are found on which hosts.  (For 7 extra credit points give the nuclear state (ploidy) of all the rust stages.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.    (8 pts) Answer the questions below about the disease cycle of ergot on rye.  (For 4 extra credit points, answer the questions for Armillaria root rot.)

 

a) What is the survival structure?

 

b) What serves as secondary inoculum?

 

c) What are the primary means of control?

 

d) What pathogen (Genus and species) causes the disease

 

 

10.  (15 pts)  For each of the following methods explain the type of situation (transmission characteristics, vectors, crops etc) in which it would work (+) and not work (-) as an effective way to manage viral disease spread

 

a.  systemic insecticide

b.  transgenic crop plants resistant to a virus

c.  planting virus-free seed

d.  fumigation of soil

e.  heat treatment of tissue