EPWS 310  EXAM 1, Fall 2000


1.  (8 pts) Explain systemic acquired resistance. Could this ever be used as a practical control measure?











2.  (10 pts) What were the important factors contributing to the late blight epidemic?  Contrast these with the components of the coffee rust epidemic in Ceylon.













3.  (12 pts) Define and give an example of the following:





      facultative saprophyte






4.  (10 pts) Contrast horizontal and vertical resistance and give examples where each would be the most effective









5.  (10 pts) List four defense mechanisms (2 structural and 2 biochemical) that plants can use to block pathogen invasion.  Which would be the most effective against nematodes?











6.  (12 pts) Discuss dissemination and overseasoning survival of plant pathogenic fungi, bacteria, nematodes, and viruses.













7.  (12 pts) A farmer has asked you to look at their potentially diseased field of tomatoes which 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.  (12 pts) Compare the use of plant resistance and cultural control if you find the tomatoes to be infected with a nematode.  Contrast this with the same control means for wheat virus.















9.  (14 pts) Define toxin.  How do host-specific and non-host specific toxins differ?  Give an example of each type and a brief description of their mode of action.


















(6 pts extra credit)   Explain the gene-for-gene-theory.