NEMATOLOGY 100                             Name:


December 16, 2004; 2 hours

(100 points total; 50 % of overall grade)

1. (15 points)

Explain the effects of the life-history strategies of the following nematodes on your design of crop rotation programs for their management:

a) root lesion nematode, Pratylenchus penetrans

b) soybean-cyst nematode, Heterodera glycines

c) rice root nematode, Hirschmanniella oryzae.

2.  (10 points)
a) Suggest options for using natural plant compounds such as root exudates, plant constituents, or other plant-derived materials in nematode management. 

b) Explain the constraints and probability of satisfactory management with each option.

3.  (10 points)
a) What approaches would you take in attempting to increasing the abundance of parasites and predators of nematodes in a soil so that it becomes  suppressive to plant-parasitic nematodes? 

b) What is the probability that you will be successful and what factors may work against you?

4.   (10 points)
Describe the plant damage and economic importance of a plant-parasitic nematode that is vectored by an insect.  Name the vector.

5.   (10 points)
a) Flooding of fields is sometimes suggested as a method of control for plant-parasitic nematodes.  However, these are aquatic organisms; how will they be killed by flooding? 

b) What are the constraints and possible environmental impacts and economic consequences of this approach?

. (15 points)

You are a member of a technical advisory committee to the California Department of Food and Agriculture. What actions would you recommend if infestations of the potato cyst nematode, Globodera rostochiensis, were found in three potato fields in the Klamath Basin of northern California?

7.  (20 points)
The following nematodes are detected in a field to be planted to walnuts near Winters, California:

  1. Heterodera schachtii (a cyst nematode)
  2. Meloidogyne incognita (a root knot nematode)
  3. Pratylenchus vulnus (a root lesion nematode)
  4. Miconchus sp. (a predaceous nematode)
  5. Cephalobus persegnis (a bacterivore)
  6. Rhabditis cucumeris (a bacterivore)
  7. Aphelenchus avenae (a fungivore).

Evaluate the damage potential to walnuts of each of these nematodes and provide a recommendation to the grower that is environmentally sound, and economically justifiable.  Indicate the nematodes that you are targeting with each procedure.

  8.  (10 points)

True (T) or False (F)

          a.  Seed galls initiated by Anguina spp. are sometimes infected by bacteria of the genus Clavibacter.

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

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

          d.  Species of Hoplolaimus behave as migratory endoparasites in some hosts.

          e.  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 saturated soil much faster than through dry soil.

          g.  Globodera rostochiensis and Anguina tritici are nematodes with narrow host ranges.

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

          i.  All nematicides are phytotoxic to growing plants; all must be used prior to planting.

          j.  Pine wilt in Japan is caused by Radopholus similis.