Name   ______________________


            EPWS 310    EXAM 3    Fall 2012                      


1.    (2 pts each) Briefly define the following terms:


heteroecious fungus



nonpersistent stylet-borne






local lesion















(2 pts extra credit)  clamp connection




2.    (9 pts) List the genus of a Basidiomycete fungus that causes root rot.  Describe how and where the pathogen overwinters, how it is disseminated, how it can be identified, and how the disease can be managed.









3.    (8 pts) For gray mold on strawberries, give the genus of the pathogen, list the survival structure, the secondary inoculum, and explain how the disease can be managed.










4.    (4 pts) Give an example of a fungal disease where plowing in the crop residue works well to limit disease and another example where it does not work well and explain your answers.








5.    (8 pts) List the steps for a (-) ssRNA plant virus to replicate beginning with entry into a cell and concluding with exit from a cell.  What steps differ if the virus is + ssRNA?













6.    (8 pts) Explain the life cycle of corn smut caused by Ustilago maidis.  Include how it overwinters, the spore type(s) it produces, how it infects, and how it causes disease.








7.    (15 pts) For 3 viruses in different groups, explain what types of symptoms they cause, what hosts they typically infect, how they are transmitted (vector and persistence), and how they can be controlled.












8.    (9 pts)  Diagram the disease/life cycle of cotton rust, indicating which spore stages are found on which hosts.  (For 7 extra credit points give the nuclear state (ploidy) of all stages.)















9.    (8 pts) Answer the questions below about the disease cycle of ergot on rye.  (For 4 extra credit points, answer the questions for apple scab.)


a) What is the survival structure?



b) What serves as secondary inoculum?



c) What are the primary means of control?



d) What pathogen (genus, species) causes the disease


10.  (15 pts)  For each of the following methods explain the type of situation (transmission characteristics, vectors, crops etc) in which it would work (+) and not work (-) as an effective way to manage viral disease spread


a.  systemic insecticide

b.  altering planting date

c.  using certified virus-free propagative material (budwood, tubers, corms, mother plants)

d.  transgenic crop plants resistant to a virus

e.  removing infected plnats from the field (rogueing)