EPWS 310 EXAM 3 Fall 2007
1. (2 pts each) Briefly define the following terms:
2. (8 pts) List the genus of a fungus that causes vascular. Describe how the pathogen overwinters, how it is disseminated, how it causes disease, and how the disease can be managed.
3. (8 pts) For a Basidiomycete fungus that that causes heart rot of trees, describe how the pathogen overwinters, how it is disseminated, and how the disease can be managed on fruit trees and on forest trees.
4. (5pts) Give an example of a fungal disease where fungicide applications work well to limit disease and another example where they do not work well and explain your answers.
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 loose smut of wheat caused by Ustilago tritici. 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. (9 pts) Diagram the disease/life cycle of wheat rust, indicating which spore stages are found on which hosts. (For 7 extra credit points give the nuclear state (ploidy) of all stages.)
9. (8 pts) Answer the questions below about the disease cycle of apple scab. (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, 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. removing infected plants from the field (rogueing)
c. planting virus-free seed
d. altering planting date
e. reflective mulch