1.  (12 pts) Define the following terms:





disease incidence



polycyclic disease



vertical resistance










2.  (10 pts)  Chose one of the following diseases (crown gall or bacterial canker) and answer the questions below about its disease cycle. For 5 extra credit  points, answer both questions.


a) Where does the pathogen overwinter?



b) How is the pathogen disseminated?



c) What are the symptoms of the disease?



d) How can the disease be controlled?



e) How does the pathogen enter the plant?



3.  (6 pts)  Draw and label a disease progress curve for a monocyclic disease.  Name a disease that would show such a plot.










4.  (12 pts) Keeping in mind the disease triangle, discuss the epidemiology of a specific (1)fungal disease, (2) bacterial disease, and (3) viral disease. 

















5.  (10 pts)  Due to your experience in this class, you have been called to look at a tomato field.  The tomatoes have chlorotic ring spots and line patterns on the fruit and darkening of stems on younger growth.  Describe the steps you would take to diagnose the problem.  What type of pathogen would most likely cause the disease?  What control measures would you suggest for the next years crop?


















6.  (18 pts) Compare the dissemination and overwintering survival of Pythium, a vascular wilt fungus, fireblight bacteria, root knot nematodes, tobacco mosaic virus, and dwarf mistletoe.
















7.  (6 pts)  What is a transgenic plant?  Discuss the merits and problems of using transgenic plants to control diseases.












8.  (10 pts.) Discuss the ways that plant parasitic nematodes penetrate, enter, and feed on plants.  What sorts of symptoms of disease are induced by nematodes?  What measures can be used to control nematodes?












9.  (8 pts.)  Crop rotation is often used to manage plant diseases.  Give 2 examples of when it would work well and 2 examples when it would not help control the disease.












10.  (8 pts.)  Discuss the role of man in plant disease.  Give examples for 3 different pathogen types.

















Make a flow chart or dichotomous key to the 7 biotic plant pathogen types.