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Microbiology 530 - Exam 2 (2000)

EXAM 2- 50 pts.

1. You receive two plants in your diagnostic lab. One is infected with lesion nematodes and the other by root-knot nematodes. (4 pts.)

a. What root symptoms does each type of nematode cause?

b. For which nematode problem would you suggest use of a genetically resistant cultivar and why?

2. What are 2 ways to determine if a plant is infected by a phytoplasma or a virus (4 pts.)

3. Name 2 plant pathogens (or their diseases) that produce growth regulators and the symptoms they cause. (4 pts.)

4. Name two other chemical weapons commonly produced by plant pathogens (2 pts.)

5. Give an example of an obligate parasite from each of the following plant pathogen groups:





6. Are all plant pathogens equally affected by environmental factors? Explain your answer with a few brief examples (6 pts.).

7. Name a common insect vector for each of these parasites (3 pts.)



Xylem-limited fastidious bacteria

8. Water is an important factor for infection by many (but not all) pathogens. What are 3 ways to minimize the time that leaves remain wet? (3 pts.)

9. You are a plant pathogenic fungus, so think like a fungus! Use appropriate terminology.

a. Describe how you might survive the impending Massachusetts winter (list of possible ways is fine) (3 pts.)

b. If you are a foliar pathogen, how will you get from the soil to the leaves of a new host plant and re-establish an infection (2 pts.)

c. If you are a root pathogen, how will you find and infect the roots of your host plant (2 pts.)

d. As a human being (now think like a person!), what are 3 ways you can interfere with these processes? (3 pts.).

Fill in the correct term. 10 pts. Do all 12 for extra credit.

a) Endoparasitc, migratory nematode (genus or common name- extra credit for both)

b) Host-specific, endoparasitc, sedentary nematode (genus or common name, extra for both)

c) Dioecious plant parasite of conifers

d) The coordinated timing of production of parasite inoculum and host susceptibility

e) Plant tissue in which spiroplasmas are found

f) Thick-walled asexual survival spore

g) Another general term for an obligate parasite

h) Structure that helps keep a germinating spore from falling off a leaf

i) Nutrient-rich area produced by root exudates

j) An enzyme that is produced continuously by an organism (an adjective, not a specific type)

k) Plant growth regulator discovered from studies of the “foolish seedling” disease of rice

l) Adjective that describes bacteria that require complex media for growth