NEMATOLOGY 100 - FINAL EXAM December 12, 1990 2 hours (10 points) 1. Describe the reproductive strategies of plant-parasitic nematodes, giving examples of genera or species. What are the advantages and disadvantages of each strategy to the nematode species in relation to conventional practices in intensive agriculture? (10 points) 2. Describe the plant damage and economic importance of a plant-parasitic nematode that is vectored by an insect. Name the vector. (10 points) 3. Describe the stimuli, their sources, and the responses that result in syncytia associated with infection by Heterodera or Globodera. (5 points) 4. What are the various above-ground symptoms associated with nematode parasitism of plants? (15 points) 5. A cotton variety that is normally resistant to Fusarium loses its resistance when planted in a particular field in Kern County. The variety performs well in this field when the soil is treated with the soil fungicide Chloropicrin. Describe the experiments that you would undertake to determine whether nematodes are the cause of the loss of resistance. (10 points) 6. Flooding of fields is sometimes suggested as a method of control for plant-parasitic nematodes. How would nematodes be killed? What are the constraints and possible impacts of this approach? (10 points) 7. Describe the principle and discuss the mechanisms of nematode management through the use of trap crops. (15 points) 8. The following nematodes are detected in a field to be planted to almonds in a sandy soil in Merced County, California: Heterodera schachtii, Meloidogyne incognita, a predaceous nematode, and at least three species of microbial-feeding nematodes. Recommend any nematode control procedures that you think appropriate, environmentally sound, and economically justifiable. Indicate the nematodes that you are targeting with each procedure. (5 points) 9. List some predators of nematodes and indicate their phyla. (10 points) 10. Ditylenchus dipsaci, Ditylenchus destructor, and Ditylenchus angustus are parasites of plants. Name at least one host plant of each and indicate the part of the plant where you would expect to find each of the nematode species.