Nematology 100 FINAL EXAM

December 11, 2008 2 hours

(100 points total;       50% of overall grade)

1)                  (8 points)

Ditylenchus dipsaci and Ditylenchus destructor are nematode parasites of plants.

a)            Name at least one host plant of each

b)             Indicate the part of the plant where you would expect to find each of the nematode species.

2)                  (12 points)

A cotton variety resistant to Fusarium sp loses its resistance when planted in a particular field in Louisiana.  The resistant variety performs well and retains its resistance in this field when the soil is treated with a mixture of 1,3 Dichloropropene and Chloropicrin.

Describe the investigations and experiments that you would undertake to determine the cause of the loss of resistance.

3)                  (10 points)

Assume that Radopholus similis, the burrowing nematode, is found attacking trees in two citrus groves in widely separated parts of California.

If you were in charge of a regulatory program, what measures would you implement to limit the spread of the nematode to other areas and to eliminate it from the infested groves?

4)     (8 points)

Sexual dimorphism (males and females having different body shapes) is found in which of the following genera?  Answer yes or no.

a)     Root lesion nematode, Pratylenchus

 b)     Citrus nematode, Tylenchulus

 c)      Stunt nematode, Tylenchorhynchus

 d)     Cyst nematode, Heterodera

 e)     Sheath nematode, Hemicyclipohora

f)        Needle nematode, Longidorus africanus

g)     Reniform nematode, Rotylenchulus reniformis

h)      False root-knot nematode, Nacobbus

5)     (10 points)

Describe the life cycle and phoretic relationships of a plant-parasitic nematode that is vectored by an insect.

6)                 (12 points)

    True (T) or False (F)?:

a)     A species of Anguina is sometimes associated with a bacterial infection of grasses caused by Clavibacter.

b)     The needle nematode, Longidorus elongatus, vectors TOBRA viruses such as grapevine fanleaf.

c)       Males of Rotylenchulus reniformis and Tylenchulus semipenetrans are capable of passing through several developmental stages without feeding.

 d)      Soil fumigants such as 1,3-Dichloropropene (Telone) move through the air spaces in soil much faster than through water.

 e)     Globodera rostochiensis and Anguina tritici are nematodes with a narrow host range.

 f)        Two of the characters separating the Nematoda from other phyla of animals are that they are non-segmented and pseudocoelomate.

7)     (15 points)

a)   What factors will you consider in designing crop rotation schemes for plant-parasitic nematodes?

 b)       Discuss the use of this approach for the genus Pratylenchus and the genus Globodera.

8)        (10 points)

 Describe the behavior, events, stimuli and responses from the time that juveniles of Meloidogyne spp. penetrate the root epidermis until a functional giant cell feeding site is established.

 9)  (15 points)
Indicate, by placing an ‘X’, all cells where the description in the header row applies to the item in the left-hand column.