Nematology 100 FINAL EXAM

December 11, 2012        2 hours

(45% of overall grade)

1. (8 points)

a) Describe the principles involved and discuss the mechanisms of nematode management in the use of trap crops. 

b) What types of nematode life history and feeding habits would be most susceptible to this approach?

 2. (8 points)

You are appointed as a member of a technical advisory committee to the California Department of Food and Agriculture.  

What actions (and why?) would you recommend if infestations of the burrowing nematode, Radopholus similis, were found in three newly-planted citrus orchards in southern California?

3. (10 points)

These three charts are based on faunal analyses of five nematode samples from an abandoned field.

a)      Describe the apparent condition of the soil food web based on this faunal analysis.

b)      What recommendations would you make for management of the soil food web if the field was to be used for vegetable production in an organic farming system?  Indicate the intended purpose of each recommendation in relation to services provided by various components of the food web  (use back of page).

4. (10 points)

True (T) or False (F)

a. Anguina agrostis is sometimes associated with a bacterial infection of grasses caused by Clavibacter.

 b. Nematode-virus relationships are non-specific and a nematode such as Longidorus africanus will vector all strains of Tobacco Rattle virus.

 c. Males of Rotylenchulus reniformis and Tylenchulus semipenetrans complete several developmental stages without feeding.

d. Species of spiral nematode, Helicotylenchus, behave as migratory endoparasites on some hosts.

 e. The ring nematode, Mesocriconema xenoplax, feeds on roots of woody perennials and is associated with increased severity of bacterial canker in peach.

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

 g. The potato cyst nematode, Globodera rostochiensis, is widely distributed in California.

 h. Ditylenchus dipsaci is a root tip feeder.

 i. Enzone is a halogenated hydrocarbon nematicide.

 j.  Some species of the nematode genus Aphelenchoides feed on fungi, others on higher plants.


5. (10 points)

Provide five differences in the life cycle, feeding habits, or host-parasite relationships between the genera Meloidogyne and Heterodera.

 6. (10 points)

Match the following. (Some letters may be used several times, others may not be used at all.  There may be several answers to each question).

_______________1. Animal parasite                                              a) Caenorhabditis elegans

_______________2. Damage to peanuts                                        b) Pratylenchus vulnus

_______________3. Predator                                                        c) Ditylenchus africanus

_______________4. Microbivorous                                               d) Rhabditis spp

_______________5. Important on walnuts                                      e) Xiphinema index

_______________6. Virus transmission                                           f) Radopholus similis

_______________7. A-rated pest (California)                                g) Trichinella spiralis

_______________8. Migratory endoparasite                                  h) Globodera pallida

_______________9. Suborder Tylenchina                                      i) Ascaris suum

_______________10.Male does not feed                                       j) Hemicycliophora arenaria


7. (18 points)

Based on your knowledge of nematode biology, available management tactics, host ranges, etc., what control measures are available and practical for:

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

b) Anguina tritici on wheat.

 c) Aphelenchoides fragariae on greenhouse-grown chrysanthemums.

 8. (8 points)

Describe the various ways that elevated temperature may be used to control plant-feeding nematodes. Include discussion on:

a) the advantages of each method.

b) the constraints of each method.

c) approaches that enhance the efficacy of each method.

d) the types of plants and nematodes for which such methods are most likely to be useful.

9. (18 points)

a) Heterodera glycines is an important economic pest of which crop in the United States?

b) Considering available strategies, including the most current information, design a sustainable management plan for this nematode.  Explain the rationale for each component of your plan.