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Glen Stanosz: Computer Simulations to Overcome the Practical Limitations on Involving Students in the Plant Disease Diagnostic Process.


We integrate exercises that utilize the multimedia computer program "Diagnosis for Crop Protection" into our curricula. Students interactively participate in a "field to lab" process to diagnose plant diseases and physiological disorders, and identify insect pests. They formulate plant health recommendations in the context of management systems for affected landscape or forest plants.

The Problem

In the simplest sense, a "diagnosis" is a statement concerning the nature or cause of some condition. However, as used by plant health professionals, "diagnosis" also refers to the process involved in determining the cause of plant disease or other damage. This process is critical to the successful application or practice of plant health protection. Yet, exposing students to the diagnostic process, and involving them in it, is one of the most difficult and overlooked aspects of our undergraduate curricula in Plant Pathology.

The difficulties involved in providing diagnostic experience to our students are many. Opportunities for field trips to view crops and forests in production and in the diseased or insect-infested state are limited by distance, season, and expense. Occurrence of disorders and their observation may not be synchronized with the order of presentation of class material. It may be impossible to immediately link gross symptomatology in the field with laboratory diagnostic procedures including microscopic examination of plant material or causal agents. Some procedures (for example culture of pathogens or soil sample analysis) normally require days or weeks for completion. Finally, class sizes and the limits on formal instructional time inhibit the "one-on-one" tutorial situation through which a student might be guided in this process of discovery.

Then why integrate exercises in diagnosis into our curricula? Most students in the undergraduate curriculum in Plant Pathology are not majors in our department. Most do not continue in Plant Pathology as graduate students and researchers. Majoring in Forestry, Agronomy, and Horticulture, for example, these students often become the first "practitioners" of plant health protection. They must make field observations and recognize when plant health is adversely affected. They will make decisions to implement pest management techniques or obtain assistance from more highly trained professionals.

Exercises in diagnosis of plant health disorders also offer other benefits to our students and teachers. By its very nature, diagnosis is a participatory process. Students become actively engaged in collecting and analyzing information. Thus, it becomes an active learning experience. Diagnosis also provides a context and mechanism of reinforcement for other course information. In addition, the diagnostic process is an opportunity for using a multidisciplinary approach, for example when different agents cause similar effects or act in concert to diminish plant health and/or economic value. Diagnosis also requires integration and synthesis of information from diverse sources, and provides an introduction to crop culture and management. Abstract principles of integrated management may become concrete when applied to particular pest and crop situations.

Our Approach

Currently available computer technology and a highly innovative software package offer a tremendous potential for us to improve our curricula by integration of diagnostic exercises for students of crop protection. We use the software "Diagnosis for Crop Protection" (developed at the New Zealand Cooperative Research Centre for Tropical Pest Management) to provide students with interactive, multimedia experiences in the process of diagnosis. Students are presented with a problem scenario and must interrogate the program to progressively disclose information needed to develop a diagnosis. Information can be presented in the form of a text window, still graphics, sound, and motion video. The software is available in both Windows and MacIntosh versions, and scenarios that are developed can be integrated into each version.

"Diagnosis for Crop Protection" scenarios provide "simulation" of the diagnostic process, from the field to the laboratory, in which space and time are compressed. Students are presented with initial scenario information including an image of the field being "visited" and explanatory text. Students then choose from various "action" or "ask" menu options. "Actions" include opportunities to look at, cut into, or collect various plant parts (leaves, roots, fruit, etc.), or insects. As they "look", images of these items are displayed with explanatory text which might call attention to key plant symptoms or signs of agents. Students also may "examine" weeds and soil and receive spatial and quantitative descriptions of damage. "Ask" menu options allow students to question the "grower" which could be a farmer, forest landowner, or homeowner. Queries include the history of the problem, past land uses, weather information, and cultural practices such as irrigation and fertilization. The software includes a "notepad" for students to record information as they make "observations" and "listen" to the grower.

When ready, students elect to return to the "laboratory." There, students can choose from procedures to further examine or test materials collected during the field visit. Selection of "microscope" results in display of an appropriate image and explanatory text. Microbes may be "cultured" on agar plates or nematodes "extracted." Appropriate images are displayed with explanatory text. Students also are given the option of sending materials to consultants for specialized services such as tests for viruses, soil nutrient analyses, or tests for pesticide residues. Results of these procedures are then displayed. Actions of each student are monitored and recorded by the program and costs are assigned to various activities. The student eventually offers a diagnosis, justification for that diagnosis, and proposes actions to be recommended to the grower. These also are recorded for later examination by the faculty or teaching staff. After entering required responses, students immediately may be provided with feedback consisting of the correct diagnosis, a review of key points that should have been observed, and the diagnostic approach that might have been followed by an experienced extension agent or crop consultant. Finally, a range of management options can be presented for consideration within the context of the particular scenario.

Purchase of the "Diagnosis for Crop Protection" software provides the owner with the capability to run problem scenarios and three sample scenarios to become familiar with use of the software. Also provided is "Scenario Builder," a user-friendly module for building the individual scenarios we propose to use in our classes. Although the mechanics of scenario building are relatively straight-forward, the process of scripting a scenario (producing the text and graphics to be inserted for each permitted potential student query or action) demands considerable time and expertise with the subject crop and malady. However, it also means that scenarios can be tailored the experience level of the student, as well as to the particular plant commodities, diseases or insects, and production systems of a region.

Students have been provided with opportunities to perform diagnoses at appropriate times in particular courses. For example, in PlPath/Entom/Forestry 500 Insects and Diseases in Relation to Forest Resource Management, students learn the biology of insects and diseases according to the affected plant part. Thus, following the unit on agents affecting foliage, students have participated in diagnosis of leaf diseases/insects. Alternatively, presentation of course information could be based on the type of pathogen. Thus, following the unit on diseases caused by viruses, students could complete virus disease scenarios. Students in this class who express an interest in a particular commodity, fruit for example, can be allowed to select scenarios created for that particular crop area.

We have developed our own set of survey questions to elicit student response to this experience. A summary of responses from students using the program has been overwhelmingly positive. Not only do students seem to appreciate the learning process offered by participation in diagnostic exercises, they indicate that these are indeed "fun."

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UW-Madison, October 1997