EPWS 310  EXAM 3, Fall 2002


1. (12 pts) Briefly define the following terms:














persistent propagative






2. (8 pts)  Compare the life cycle to the disease cycle of Armillaria root rot including the types of spores it produces, how it overwinters, how it is disseminated and how it can be controlled.










3. (7 pts)  Give the genus of a fungus that causes cankers on the trunks of trees.  Describe how the pathogen overwinters, how it is disseminated and how the disease can be managed.








4. (12 pts) As a researcher, you have undertaken a project to develop a fungal biocontrol agent to manage stem rust of wheat.  Which spore stage in the life cycle will you target?  Explain why that spore stage is preferred and why others are not acceptable.  Diagram the disease/life cycle of the pathogen, indicating which spore stages are on which hosts.













5.  (10 pts)  Answer the questions below about the disease cycle of brown rot of peaches.  (For 5 points extra credit, answer the questions for ergot.)


a) What is the survival structure?



b) What serves as primary inoculum



c) What serves as secondary inoculum?



d) What is the primary means of control?



e) What pathogen causes the disease?




6. (12 pts) Describe the steps for a +ssRNA plant virus to infect and replicate in a plant beginning with arrival onto a plant and concluding with exit from the plant.








7.  (12 pts) For each of the types of disease below describe two means of control and state how the value of the crop will influence the choice of control (ie. Will you chose the same control for high $ value and low $ value crops?).


a)  leaf spot disease


b)  vascular wilt disease


c)  post harvest soft rot


d)  Rhizoctonia root rot



8.  (15 pts)  For 3 viruses in different groups, discuss what types of symptoms they cause, what are the hosts, how they are transmitted (vector and persistence), and how they can be controlled.














9. (12 pts) Compare and contrast loose smut and covered smut of wheat.  What spore types do they produce, how do they overseason, how are the disseminated and what measures work to control them?