1.  (12 pts) Define the following terms:


compatible interaction












disease pyramid







2.  (10 pts)  Chose one of the following diseases (Erwinia soft rot or fireblight) 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.  (10 pts)  Compare and contrast monocyclic and polycyclic diseases giving specific disease examples.  Draw appropriate disease progress curves of each type and label. 













4.  (9 pts) Keeping in mind the disease triangle, discuss the epidemiology of a specific (1)fungal disease, (2) bacterial disease, and (3) viral disease. 


















5.  (5 pts)  Why doesn’t every spore that lands on a chile plant cause disease?












6.  (10 pts)  Due to your experience in this class, you have been called to look at a cotton field.  The plants are wilting and show vascular discoloration.  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?


















7.  (12 pts) Compare the dissemination and overwintering survival of downy mildew, a leaf spotting fungus, Agrobacterium, root knot nematodes, beet curly top virus, and true (leafy) mistletoe.















8.  (5 pts)  Against what plant disease would you recommend a genetic engineering company develop transgenic plant resistance and explain your choice of disease?







9.  (10 pts.) Compare and contrast plant sedentary endoparasitic nematodes with migratory ectoparasitic nematodes in the way they feed on plants.  What sorts of symptoms of disease are induced by each group of nematodes?  What measures can be used to control nematodes?












10.  (4 pts.)  Biocontrol of plant pathogens is a an environmentally friendly method to manage plant diseases.  Give an example of when it would work well and an example when it would not help control the disease. For 4 pts extra credit, give an extra example of when biocontrol would and would not be effective.









11.  (8 pts.)  How can abiotic factors cause plant disease.  Give examples for 3 different abiotic factors.












12.  (5 pts)  Choosing either Phytophthora root rot of chile or powdery mildew on chile, explain which factors you would measure in designing a predictive model of disease in New Mexico.