Implementing a Case
Explore how the case "Zea's Wild Roots" was implemented in a general education biology case at Southeast Missouri University.   The case was used to open a unit on ecology early in the course. Students were to consider the farm as an ecosystem and to research relationships among the components of that ecosystem.   

The Case: Zea's Wild Roots

For the last few years there has been big midsummer outbreak of disease on corn (Zea mays or maize) in the U.S. caused by a mold-like fungus. Derrick Hernandez and Maria Santini are students trying to understand the disease and come up with ways to fight it. They are hopeful that wild corn from Central America, called teosinte will be able to resist this fungal disease.

Last summer Maria and Derrick went to Mexico to study teosinte in the field. They had many adventures, and both got sick. Now we pick up the story back at home, later in the year, when Maria, her husband Marcus, and Derrick are having dinner together.

"As long as weíve known each other, Iíve never asked. How did you two meet?" Derrick asked Marcus as the dinner got underway.

Between bites, Marcus replied, "I met Maria while working with OXFAM, a hunger relief organization. We were volunteers."

"Remember stuffing all those envelopes and making all those calls?" Maria said as she flashed Marcus a smile.

" I sure do. Hey Derrick, youíll be interested in this. When we were at OXFAM, corn crops were being lost in Africa due to some virus." "Really? Which one?" Derrick asked.

"Maize streak virus," Maria added. "And get this. It turned out that one of the teosinte species was resistant to the virus. Through plant breeding they were able to make corn hybrids resistant, too, and that offered real hope in Africa. Thatís when I knew I was going to become a corn breeder."

"Thatís a great story," Derrick said. " Do you know how come I decided to study corn diseases? I have this uncle in Kansas who has a big farm - 700 acres. He grows corn on most of it, as cattle feed. He tells the story of how, in the early 70ís, Southern corn leaf blight hit so hard that his glorious green fields died in a matter of days. He really had to struggle for a few years to make up that loss. And it wasnít only his farm. He just couldnít understand why every field in the county was affected."

Maria nodded her head knowingly and said simply, "Weather..."

PDF handout of this case
Margaret Waterman and Ethel Stanley.
BioQUEST Library V. CA: Academic Press, 1998.
Case is excerpted and modified for this publication

Three 50 minute classes are set aside for in-class work.

Day 1

  • Consider a brief, whole class discussion to insure basic understanding of ecosystems and types of relationships.
    Briefly describe investigative case-based learning
  • Hand out case and worksheet to students, divided into three groups of about 10 students each
  • They read the Zea case and then the directions.
  • Students discuss questions in their group for about 12 minutes, followed by a large group discussion of ecosystems and their components.
    PDF handout of the directions/worksheet
  • Then the groups begin to explore resources about corn growth, plant diseases, and fungal growth.

Day 2

  • Class is held in a computer lab.
  • Students are provided with selected resources to get started and then conduct their own web-based searches to further understand plant growth and fungal diseases.
  • An instructor is available to help groups find resources and develop their own questions.

Day 3

  • Students bring in briefing papers on the ecological interactions they studied, with enough copies for each member of their group.
  • In the groups, each student makes a 90 second presentation of their findings.
  • When all are done, the group identifies common features of the interactions that were studied.
  • The exercise ends with a whole class discussion of the nature of interactions within ecosystems.
  • Because of the host-pathogen interactions, discussion also includes basic population biology, species interactions, and human population growth.


PDF handout of these resources.


Agrios, G. Plant Pathology, 2nd ed. 1993.

Aldrich, S.R., W.O.Scott and E.R. Leng. Modern Corn Production. Second Ed. Champaign, IL: A & L Publications, 1975.

Christensen, Clyde M. Molds, Mushrooms, and Mycotoxins. Minneapolis: U. of MN Press, 1975.

Dix, N.J. and J. Webster. Fungal Ecology. London: Chapman and Hall, 1995.

Jones, D.G. and B.C. Clifford. Cereal Diseases: Their Pathology and Control. NY: Wiley, 1978.

Manglesdorf, P.C. Corn: Its Origin, Evolution and Improvement. Cambridge, MA: Belknap Press, 1974.

Moore-Landecker, E. Fundamentals of the Fungi, 4th ed. Upper Saddle River, NJ: Prentice Hall, 1996.

Russell, B. The Story of Corn.NY: Knopf, 1992.

Shurtleff, M.C. Compendium of Corn Diseases, 2nd. ed.Minneapolis: American Phytopathological Society, 1980.

Web Sites (as of April 2002)

Southern Corn Leaf Blight Symptoms on Corn

Nature of Corn - a good place to begin

New evidence on corn ancestry

A search engine for the Corn Growers Guidebook

Choose "diseases & nematodes" in the pull down menu, or "growth and development"

Diseases management by crop

Extensive index of articles about various plant diseases

National Corn Handbook (check out nos. 4 (disease management and 10 history of corn)

The Maize Page: many linked resources

How Corn Grows (this is a huge file)

Oxfam America

LifeLines OnLine Home

Copyright 2000
Margaret A. Waterman, Southeast Missouri State University
Ethel D. Stanley, BioQUEST Curriculum Consortium, Beloit WI