1.     (2 pts each)  Define the following terms:





horizontal resistance






systemic acquired resistance






disease severity



covered smut



dwarf mistletoe



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







3.     (6 pts)  Crop rotation is often used to manage plant diseases of annual crops.  Give a disease example when crop rotation will work well and an example when it will not help control a disease of an annual crop.







4.      (12 pts)  Chose one of the following bacterial diseases (crown gall and angular leaf spot of cotton) 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 powdery mildew on chile or Verticillium wilt of cotton, explain which factors you would chose in designing a predictive model of disease for 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  (1) Phytophthora capsici which causes chile root rot, (2) Penicillium causing post harvest disease, (3) fire blight bacteria, (4) root knot nematode, (5) beet curly top virus, and (6) dodder.















9.  (5 pts)  a) Migratory endoparasitic nematodes can cause severe problems on hosts such as peanut.  How do they interact with the plant? What sorts of symptoms do the cause?











10  (10 pts)  Due to your experience in this class you have been called to look at a tomato greenhouse operation in northern New Mexico.  You see that the plants are very stunted, and the leaves on the top part of the plant are yellow with purple veins and have necrotic margins on the leaves. The plants have many small poor quality fruit.  The grower notes that there was an insect problem about 6 weeks before, but none since then.  Describe the steps you will take to diagnose the problem.  What type of pathogen would most likely cause the disease?  What control measures would you suggest for the next yearŐs crop?














11. (5 pts)  Phytophthoa ramorum,which causes sudden oak death, is one of the most important disease problems in currently in plant pathology.  You are writing a grant for funds to develop resistance (transgenic or conventional) to the disease in coastal redwoods, which are completely susceptible to the fungus.  What component or pathway will you try to improve?  What types of genes will you modify or add to the plant?