5 Apprehending plant killers

By Rebecca Hite

Provided by Kenan Fellows Program.

In the final lesson of this unit, students select a particular type of plant pathogen to research. They will create a wanted poster to educate their peers and the public about the impact of this plant disease. Plant pathogens can kill crops and have historically cost human lives. Today they contribute to billions of dollars of economic losses and less food for a growing world.

CSI Dublin: The Hunt for the Irish Potato Killer is an integrated unit that incorporates earth science, biology, biotechnology, and art to allow students to apply their understandings of epidemiology and plant pathology into the historical context of science and human health. This unit is best used after previous units or discussions on DNA, biotechnology, taxonomy, bacteria, viruses, plants, protists, fungi, and immunity.

Learning outcomes

The learner will:

• Select a plant pathogen of interest
• Use the library and internet resources to research the plant pathogen
• Create a wanted poster outlining the danger of the pathogen to the public

Teacher planning

Time required

This lesson requires 100 minutes of class time depending on student abilities levels, resources, and library availability.

• Pre-activity discussion: 5 minutes depending on student questions
• Student activity: 90 minutes depending on resources available
• Post-activity discussion: 5 minutes depending on student questions

Materials needed

• clean printer paper
• colored pencils
• pens
• glue sticks
• scissors
• rulers

Technology resources

Students will need access to computers with internet connectivity.

Student handouts

Pre-activities

Prior knowledge and vocabulary

Students should understand the steps of the scientific method as well as terms such as pathogen, host, taxonomy, ecology, symbiotic relationships, parasitism, bacteria, viruses, oomycetes, and fungi. They should have knowledge of general epidemiological terms including susceptibility and occurrence.

Activities

1. To open the activity, the teacher should display an old time wanted poster to show students how authorities warned the public to be on the lookout for dangerous criminals.

This is an example of a wanted poster. Students will create a wanted poster calling for the capture of a plant pathogen. Use the rubric provided in the Assessment section to explain the information that must be included in this project.


2. The teacher will explain that in order to prevent the spread of pathogens, the biology of the pathogen must be researched to identify its unique characteristics and to warn people about how to prevent its transmission. Students should brainstorm how different pathogens might affect their hosts. Using the handouts provided, students should select a plant pathogen to research.
3. Students should create a hypothesis based upon the information from their observations as well as the pre-lab discussion. In their hypotheses, they will include what they think they will find out about the plant pathogen, how it may infect its host, and if they think it can infect other plants, animals or people. They will estimate how much the pathogen costs globally to farmers and describe how it might be similar to Phytophthora infestans. Make sure all students have recorded their own unique hypotheses before they begin their laboratory activity.
4. They should begin their research focusing on the ten questions on their lab sheet. You may wish to provide students with a copy of the grading rubric so they can see how they are going to be assessed. Remind students to record their sources and look for concrete data including percentages, ratios, and other numbers (quantitative data) as well as qualitative data. Students will be providing the following information and answering the following questions:
   • Include photographs of the affected plant and of the suspect/pathogen.
   • How can you tell it has struck its victim? What should the public be on the lookout for? Identification includes signs, symptoms, and detection systems.
   • Describe or draw the pathogen’s life cycle, and reproduction process. Provide its category, taxonomy, alias, and any known accomplices (similar plant pathogens).
   • Who is/are its common victims? Can it move between species? Where does it hide out when it is not directly infecting its preferred host?
   • What is its mode of transmission? How does it diffuse across space and time? How does it find or select its next victim?
   • Where has it been spotted in the world? What is its geographic distribution? Is it rare and deadly (like a new species or variety) or common and treatable? Rank it on a scale of 1 (public enemy #1) to 10 (common and not very harmful).
   • What environmental factors are optimum for its spread?
   • What type of plants or populations are most at risk?
   • What type of weapons are effective against this pathogen?
   • Outline its significance to human life and the environment. What is the economic cost of lost crops or plants (locally or globally)? Describe its historical context. Are any other systems affected by an outbreak of this plant pathogen?
5. Students will also answer the following analysis questions:
   • Was your hypothesis supported or rejected? Why or why not?
   • Why do you think plant pathogens are not as visible as animal diseases? Do they cause the same level of harm to people? Defend your answer.
6. As students finish their research, they should use a program such as Microsoft Word or Publisher to create their wanted posters.
7. The student final projects should be their lab sheets and wanted posters.
8. Assure students that only their data questions will be assessed upon accuracy whereas the rest of their score depends on the thought and quality of their responses. Ensure that all students are able to complete the assignment.

Assessment

The teacher will score the wanted poster based upon the grading rubric provided. It is recommended that the teacher create a wanted poster of P. infestans to use as sample work.

Modifications

For ESL and ELL students, they may use an online translator such as Babelfish to translate entire web pages into their preferred language for information about their plant pathogens.

Extensions

• Extended topics related to this lesson include history, art, and epidemiology.
• You can use data from pathogens to create relative risk and risk ratio calculations.

Comments

• It is important for students to understand the importance of observations in formulating a hypothesis. Teachers should foster the creative and unique thought process that the hypothesis requires and emphasize that there is no right or wrong answer, only supported or not supported.
• As students are conducting their online research, it is important they use peer-reviewed or otherwise credible resources. They should use well known entities like the American Phytopathological Society (APS), scientific journals, or government and university websites. Looking at Wikipedia might be a good start, but they should use the external links provided with the entries to examine the original sources for information recorded on their lab sheets.

• Next:

National standards

In addition to meeting objectives of the North Carolina Standard Course of Study, this lesson plan addresses the following national standards:

Content Standard C

As a result of activities in grades 9–12, all students should develop understanding of:

• interdependence of organisms

Content Standard E

As a result of activities in grades 9–12, all students should develop:

• Abilities of technological design
• Understandings about science and technology

Content Standard F

As a result of activities in grades 9–12, all students should develop understanding of personal and community health, population growth, natural resources, environmental quality, and natural and human-induced hazards.

Sources and credits

Chia-Hui “Julia” Hu, post-doctoral researcher in the department of Plant Pathology at North Carolina State University under the direction of Dr. Jean Beagle Ristaino, professor of Plant Pathology assisted with the development of this lesson.

The Ohio State University Extension provides the fact sheets in their Plant Disease Fact Sheet Index. These facts sheets may be copied without permission for educational, non-profit purposes as long as credit is given to Ohio State University Extension.

Contents: CSI Dublin

• Next:
• Previous: Identifying a potato killer via PCR and gel electrophoresis

Learn more

• Nematodes as agricultural pests From the University of Nebraska-Lincoln, this list includes nematodes associated with corn, potatoes, soybeans, sugarbeets, and other crops.
• APSnet The American Phytopathological Society website provides a wealth of information and research about plant pathology. A section for educators includes plant disease lessons, laboratory exercises, topics in plant pathology, an illustrated glossary, and more.
• Plant disease series index This resource from the Ohio State University Extension includes a wide variety of fact sheets about plant diseases and treatment.

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