EPWS 310    EXAM 3    Fall 2003              Name   _________________

 

 

 

1.    (2 pts each) Define the following terms:

 

clamp connection

 

 

persistent circulative

 

 

sclerotia

 

 

heterokaryon

 

 

virion

 

 

chlamydospore

 

 

(2 pts extra credit)  rhizomorphs

 

 

2.    (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.

 

 

 

 

 

 

 

 

3.    (6 pts) For a Basidiomycete fungus that causes wood rot, describe how the pathogen overwinters, how it is disseminated, and how the disease can be managed.

 

 

 

 

 

 

 

4.    (6pts) Give an example of a fungal disease where cool storage conditions works well to limit disease and another example where it does not work well and explain your answers.

 

 

 

 

 

 

 

5.    (10 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.  Include how it overwinters, the spore types 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.    (12 pts) In your job for Cotton Incorporated you are asked to develop a biocontrol agent (fungal or bacterial) to control cotton 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. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.    (8 pts) Answer the questions below about the disease cycle of grey mold of strawberries.  (For 4 extra credit points, answer the questions for white mold of beans.)

 

a) What is the survival structure?

 

b) What serves as secondary inoculum?

 

c) What are the primary means of control?

 

d) What pathogen causes the disease

 

 

10.  (`16 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.  removing weed hosts

c.  heat treatment of tissue

d.  using virus-free budwood