1.     (16 pts)  Define the following terms:














systemic acquired resistance



polyetic disease






damping off



2.      (6 pts)  Give specific examples of how an environmental factor can cause abiotic disease and how plant nutrition can cause abiotic disease.








3.     (6 pts)  Sanitation practices such as removing crop residue and cleaning implements can be useful methods for managing plant disease.  Give a disease example when sanitation will work well and an example when it will not help control disease.







4.      (12 pts)  Chose one of the following bacterial diseases (fire blight and bacterial canker of stone fruit) and answer the questions below about its disease cycle.  For 6 extra credit points, answer both questions.


a)     What are the symptoms of the disease?



b)    How does the pathogen enter the plant?



c)     How is the pathogen disseminated?



d)    Where does the pathogen overwinter?



e)     How can the pathogen be controlled?



f)  What is the genus of the pathogen?




5.     (10 pts)  Draw and label disease progress curves for polycyclic and monocyclic diseases.  Name a disease that would show each type of curve.












6.     (6 pts)  Choosing either wheat rust or Fusarium wilt of tomato , explain which factors you would chose in designing a predictive model of disease for northern New Mexico and why.  For 3 pts extra credit answer for both diseases.








7.      (12 pts)  Using the disease pyramid, discuss the epidemiology of a specific (1) fungal disease, (2) bacterial disease, (3) viral disease, and (4) nematode disease.















8.  (12 pts)  Compare the dissemination and overwintering survival of Pythium, a fungus such as Alternaria or Septoria that causes leaf spots, crown gall bacteria, Rhizoctonia, alfalfa mosaic virus, and true leafy mistletoe.















9.  (10 pts)  Due to your experience in this class, a homeowner calls you to look at their roses.  The person explains that the plants rapidly wilt and die before the leaves even have time to fall off.  They have 30 roses and 3 have already died.  Describe the steps you will take to diagnose the problem and then prove what is causing the disease.  That type of pathogen would most likely cause the disease?  What control measures would you recommend for the roses?









10.  (5 pts)  a) Sedentary endoparasitic nematodes can cause severe problems on hosts such as tomato.  How do they interact with the plant? What sorts of symptoms do the cause? 






(5 pts)   b)  With money from tomato growers to develop resistance to this type of nematode, what host resistance systems would you try to improve?