EPWS 310 EXAM 1, Fall 1999

1. Explain the gene-for-gene theory. Does the hypersensitive response agree with this concept?






2. What were the important factors contributing to the late blight epidemic? Contrast these with the component of the Southern corn leaf blight epidemic.









3. Define and give an example of the following:



obligate parasite



4. Diagram a generalized plant disease infection cycle. Indicate where control measures could be the most effective.











5. List four defense mechanisms (2 pre-formed and 2 induced) that plants can use to block pathogen invasion. Which would be the most effective against a fungal pathogen?









6. Compare and contrast penetration into plants by fungi, bacteria, nematodes, and virus.








7. A farmer has asked you to look at their potentially diseased field of strawberries with large chlorotic spots on the leaves. Some of the plants are wilting. What will you look for initially in diagnosing the problem? What steps will you need to go through to determine what is causing the problem?












8. Compare the use of plant resistance and cultural control if you find the strawberries to be infected with a root pathogen. Contrast this with the same control means for wheat rust.











9. You have become a powerful plant pathogenic fungus. Describe how you will infect a corn plant and move into the cytoplasm. What enzymatic tools will you use.













10. Why aren’t all fungal spores that land on a chile plant able to infect it and cause disease?