Nematology 100 FINAL EXAM

December 12, 2005           2 hours

(100 points total;  50% of overall grade)

1.  (10 points)
Describe the ways that elevated temperature is used to control plant-feeding nematodes.  Include discussion on:

a) the advantages of each method.

b) the constraints of each method.

c) approaches used to enhance the efficacy of each method.

 
 
2.  (15 points)
Based on your knowledge of nematode control, biology, distribution, host ranges, and environmental conditions, what control measures are available and practical for the following nematode problems:
 
a) Potato cyst nematode, Globodera rostochiensis, on potatoes in Mexico.

 

b) Root lesion nematode, Pratylenchus vulnus, on grape rootstocks in a nursery.

 

c)  Pine wood nematode, Bursaphelenchus xylophilus on pine trees in Korea.

 d)  Burrowing nematode, Radopholus similis, on banana in India.
 

 e)  Stem nematode, Ditylenchus dipsaci, on alfalfa in California

 

3.  (10 points)
Indicate, by placing an ‘X’, all cells where the description in the header row applies to the item in the left-hand column.
 

4.  (10 points)
Describe the mode of parasitism and survival of the rice root nematode, Hirschmanniella oryzae. 

At least two related species, H. belli and H. pomponiensis, occur in California.  What factors govern their importance in rice production?
  
5.  (10 points)
What strategies are available for management of nematodes in perennial crops?  Consider options to be used before planting and options for established orchards.

6. (10 points).

Which feeding-habit groups of plant-feeding nematodes commonly exhibit resistance to desiccation? Use examples of genera, species, life stages and host crops.

7. (10 points).

The reniform nematode, Rotylenchulus reniformis and the sting nematode, Belonolaimus longicaudatus are parasites of plants.

Name at least one host plant of each, indicate the part of the plant where you would expect to find each of the nematode species, and indicate the geographic distribution of each species.

8. (10 points).

The foliar nematode, Aphelenchoides fragariae, is found distorting leaves in a greenhouse that produces ornamental ferns for the restaurant industry. Provide advice to the producer regarding management or control of the problem.

9. (10 points).

True (T) or False (F)

a. Bacteria are carried into seed galls by spiral nematodes, Helicotylenchus spp.

b. Sexual reproduction occurs more commonly in the cyst nematodes than in the root-knot nematodes.

c. Males of pin nematodes, Paratylenchus spp. and citrus nematode, Tylenchulus semipenetrans, are capable of passing through several developmental stages without feeding.

d. Nematophagous fungi are present in many soils but may be below suppressive levels

e. Soil fumigants such as 1,3-Dichloropropene (Telone) should be applied in wet and cold soils so that they persist longer to kill nematodes.

f. Globodera rostochiensis and Anguina tritici are nematodes with extensive host ranges.

g. One of the characters separating the Nematoda from other phyla of lower animals is that they have a well-developed circulatory system.

h. Nematodes of the genus Rhabditis attack higher plants by piercing root cells with their needle-tipped stylets.

i. Host-plant resistance has been identified and developed in cultivated plants most commonly for root-knot and cyst nematodes.

j. The stunt nematodes, genus Tylenchorhynchus, are important sedentary endoparasites of grapevines.

10. (5 points).

What are bullae?