Exam 1- 50 pts.
1. What is a common leaf symptom and sign for the following plant pathogens: (6 pts.)
Fungus
Bacterium
Virus
2. You receive a diseased plant specimen and begin isolation procedures. Within 48 hr, you observe septate mycelium in the culture plate. (4 pts.)
What is one fungal or fungallike group that you are certain the pathogen does not belong to:
What is one fungal group that it might belong to:
3. Briefly, describe the purpose of Koch’s postulates and 2 situations in which their application may result in some difficulty. (4 pts.)
4. You receive some plant pathogenic bacterial cultures in the mail, but the labels have fallen off. The labels say: Clavibacter, Erwinia,and Xanthomonas. What characteristics of these cultures will allow you to replace the labels properly? (6 pts.)
5. Plant pathogenic bacteria produce no spores. How do they survive Massachusetts winters? (2 pts.)
6. What are the biological characteristics that define the fungi?
Why are Plasmodiophoromycetes not true fungi?
Why are Oomycetes not true fungi? (6 pts.)
7. Immunoassays are rapid and accurate means to detect viruses. Why are bioassays still used (i.e. what are the advantages of bioassays)? (2 pts.)
8. Name 3 kinds of insects that commonly transmit plant viruses:
What are some limitations to the use of insecticides to prevent virus transmssion? (5 pts)
9. Ascomycetes and other fungal groups are classified by the sexual spores and fruiting bodies that they produce. How are Imperfect Fungi (Deuteromycetes) classified? Use examples in your answer. (3 pts.)
10. You receive a package that contains plants that may have been injured by herbicide drift or may have a virus. With no further information, how might you determine which is the problem? (2 pts.)
Fill in the correct word. 10 pts. Do all 12 for extra credit.
designation of bacterial subspecies based on host plant
structure on mycelium that is found only in Basidiomycetes
early bacteriologist for whom a facultative anaerobic genus is named (first and last name)
most common type of nucleic acid found in plant viruses
motile, asexual spore
open, cup-shaped ascocarp/ascoma
pear-shaped fruiting body with opening at the top, containing conidia
sexual spores of the Ascomycetes
general term for an organism with nuclei
a parasite that requires a living host
a mass of mycelium with a dark rind
virus transmission that can occur without a latent period
