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Chapter 3 Instructor Resources​

Coffee and Rubber: Monocultures and Quarantines

People determined long ago that the temporary segregation, or quarantine, of sick people helped protect the healthy individuals. We now know that the first introduction of an exotic pathogen into a population with little resistance is very dangerous. Some of the most significant plant disease epidemics have been caused by introduced pathogens. Famous examples include coffee rust and South American leaf blight of rubber. Today many countries and regions have elaborate plant quarantine systems to monitor pests and pathogens to protect our plants.

• Chapter 3 Podcast

  Chapter 3 Podcast

  Listen to the Podcast (mp3)
  

  The short podcast provided for each chapter includes a review of a major concept or issue, clarification of an important point that can be confusing to students, and questions for students to think about. This podcast describes the roles that people play in spreading plant diseases and clarifies the taxonomy of plant-pathogenic fungi.

• Short Writing Assignments

  Notes: These assignments require each student to write a paragraph (introductory sentence, body, concluding sentence) and can be completed in 10–15 minutes in class. They provide a good way to check student comprehension and to improve student writing skills. See Chapter 1 for a simple grading system.

  
  

  1) Roles of People in Plant Disease Epidemics

  You have now learned about historically important epidemics of four different plant diseases: late blight of potato, downy mildew of grape, coffee rust, and South American leaf blight of rubber trees. In each epidemic, people played an important role in promoting or slowing the development of the disease. Using these four diseases as examples, describe two ways in which people’s actions enhanced the development of plant disease epidemics and two ways in which people attempted to slow or stop these epidemics. Please use a different disease for each example.

  
  

  2) The Effectiveness of Quarantines

  Quarantines have been used in the management of both coffee rust and South American leaf blight of rubber trees. While each disease was present on its host plant growing in its native habitats, neither disease caused major problems until the plant was brought under cultivation. Describe at least two differences between the natural and plantation systems that affect the development of disease epidemics. Also discuss why the two epidemics were more severe when the plants were grown in the plantation systems.

  
  

  3)Monoculture and Plant Disease Epidemics

  You have now learned about several plant diseases (including late blight of potato, downy mildew of grape, coffee rust, and South American leaf blight of rubber) in which the practice of monoculture played a significant role in the development of an epidemic. Define the term monoculture, and describe at least one advantage and one disadvantage of using the practice. Use one of the disease systems you have learned about as an example.

  
  

  4) Quarantines for Plant Disease Management

  The overall goal of plant pathologists is to manage plant diseases. So far, you have learned about a number of disease management strategies, including sanitation, eradication, host resistance, and pesticide use. Now, you have been introduced to the concept of managing plant diseases through the use of quarantines. Describe two attributes of a plant disease that might allow for the successful use of quarantines as a management strategy. Also, give an example of a plant disease that has been successfully managed through the use of quarantines and an example of a plant disease that is unlikely to be managed with quarantines.

  
  
• Longer Writing Assignemnts

  1) Quarantine Exercise

  1. If you were a commercial vendor of fruits and vegetables, how could you get a permit to import a specific commodity from a specific country? Go to the USDA–APHIS website to find out
  2. What plant pathogens are under quarantine in your state? Go to National Plant Board Website
  3. Briefly, describe a quarantine alert for a plant pathogen in the United States in the last 60 days. Use the Phytosanitary Alert System Website to find these details:
     • The name of the disease
     • The name of the pathogen
     • The type of pathogen (fungus, bacterium, nematode, virus, etc.)
     • Where the pathogen was found
     • What quarantine requirements have been established
     
     

  
  

  2) The effectiveness of quarantines to manage plant diseases

  Select a quarantine that has been in the news recently. (Examples from 2010 include the thousand cankers disease quarantine in North Carolina and the chestnut blight quarantine in Victoria, Australia.) Then write a short paper (~ 350 words) in support of or opposition to the quarantine.

  Here are some questions to consider:

  • What is the value of the crop/plant to the producing and consuming state or country?
  • What is the means of dissemination of the pathogen (and therefore its likelihood of being successfully quarantined)?
  • What are the costs and effectiveness of possible alternative management strategies.

  
  

  Notes:

  • You can make the audience for the assignment someone other than yourself—for example, a legislator or other government official. The selection of audience should dictate the style of writing students use.
  • Opinion papers such as this can be written in several drafts: Draft 1 (evaluated but not graded) summarizes the facts; draft 2 (also evaluated but not graded) incorporates the student’s opinion, supported by the facts; and draft 3 is a polished version of draft 2, which is finally graded. Students appreciate the opportunity to get feedback on their writing and thinking before being assigned a grade. This system also provides an opportunity for students to learn to separate facts from opinions and to evaluate the biases of different sources of information.
  • You can provide students with a reference list (including links), so that this is an exercise in evaluating and using information, rather than finding it. Extra credit can be given for sources with new information that students find and use in their papers.

  
  

  Evaulation of Paper

  Criteria used in evaluation can include the following:

  • Accuracy and completeness of factual information
  • Development and support of opinion
    
  • Overall organization and clarity
  • Mechanics (e.g., spelling, grammar, sentence structure)
  • Use of supporting references

  
  

  Important Note: This paper has no “right” or “wrong” conclusion. The student can take either side of the issue (pro-quarantine or anti-quarantine), include the pertinent facts, and use them to support his or her position.