Plant Pathology: Principles and Applications


General Information

The case study assignment is an opportunity for you to learn in detail about two diseases of a crop of your choice. As you will be sharing these case studies with the other students in the class, this is also an opportunity for all students to receive information about variety of crop diseases. You will create 2 case studies, one for each course module. The module 1 case study must focus a disease caused by a fungus or oomycete. For module 1, the disease must be caused by a bacterium, virus, or nematode. If a disease is caused by a complex of pathogen species, it is suggested that you focus on the most common or important species in that complex. You may also choose whether to complete each the assignment in the form of write-ups (Essays) or recordings of slides and narration (Videos).



Item Due date
Report selection of crop and diseases/pathogens and mode of presentation (essay or video) to instructor via email June 14
Case study 1 rough draft for instructor comment (optional) July 2
Case study 1 final version for grading July 9
Case study 2 rough draft for instructor comment (optional) August 5
Case study 2 final version for grading August 12



Topic elements

For each case study, be sure to include these elements:

Disease importance

·      Describe monetary loss or loss in yield

·      Describe the geographic range where the disease occurs

Pathogen biology

•         Symptoms and/or signs associated the disease, and effects of infection on growth/yield – support the descriptions with photographs of the symptoms

•         Disease cycle – provide a description or diagram that explains how the pathogen survives between growing seasons, disperses to and between host plants, and penetrates into the host plant. Diagrams may contain pictures and captions. Diagrams can be original or may incorporate portions of published diagrams, but inclusion of an non-modified published diagram is NOT allowed.

Environmental influences

•         Identify the most important environmental conditions that favor the pathogen’s survival, dispersal, and pre-penetration stages

•         Identify environmental conditions that predispose the plant (i.e., causes the plant to be more physiologically susceptible) to infection

Pathogen-host interactions

·         Pathogen attack mechanisms – Summarize the knowledge regarding the pathogen’s mode of nutrient acquisition and mechanisms that result in the symptoms. If there is little information available specific to the disease, draw inferences from similar diseases.

·         Host defense mechanisms – Summarize the knowledge regarding the biochemical mechanisms by which the host plant inhibits infection. If there is little information available specific to the disease, draw inferences from similar diseases.

Disease management

•         Most common procedures – describe the most commonly recommended procedure(s) used for managing the disease

•         Effectiveness of management procedures – provide representative data illustrating the effectiveness of the procedure(s).


General guidelines

·         Write your essays or produce your videos as if you are educating your fellow students about your diseases.

·         Provide clear, concise presentation of each topic element.  While it is important to be accurate and thorough, avoid including non-relevant information.

·         Use the technical terms that you find in the literature, but also explain in plain English the meaning of more uncommon technical terms. For example: “Signs of infection by organism X are basidiocarps (mushroom-shaped spore-producing fungal bodies) growing from infected trees.”

·         As much as possible, information should be provided in graphic (photos or diagrams) or tabular form. Each photo, diagram, and table must be labelled. The source of the photo, diagram or table, if taken from the literature or the internet, must be cited. It is best to generate to your own diagrams to explain complex processes, e.g. disease cycles. When using a diagram generated by some else, avoid presenting it in its original form.  Instead, make every effort to simplify the diagram to eliminate extraneous information or to clarify labels.

·         Provide a bibliography of information sources at the end of each essay/video.


Format for Essays

·         For each case study, keep the text to 6 pages (double-spaced) or less.

·         Photos, diagrams, tables and the bibliography can be embedded into the text or provided in an appendix. In either case, pages containing these items are not counted in the page limit.

·         Cite the source of information in the text

·         Use headings to divide the essay into topics

·         Use 1 inch margins, 11 or 12 font, and double spacing.

·         Save essays as text files, preferably in rich text (rtf) format.  The instructor can add comments directly to a text file; this is more difficult with a PDF file.



Format for videos

·         Format slides and fonts to be viewed on standard (16:9) monitors.

·         For each case study, keep the video recordings to less than 30 minutes.

·         As a ‘rule of thumb’ there should be, on the average, 1 slide per minute of narration.

·         Provide a title for each slide and use headings there are multiple topics per slide

·         Use bullet points or numbers as appropriate to separate pieces of information in a slide. Avoid entire sentences and paragraphs

·         Within every slide, cite the source of information

·         Display the Bibliography for each recording as a slide at the end of the file. No narration is necessary for the Bibliography slide.

·         Powerpoint is the suggested tool, but other slide-making programs that also allow you to record narration are acceptable.  If you have any questions as to whether files produced using your slide/recording program can be opened on other computers, you can send a test video to Dr. Yuen.

·         If using Powerpoint, remember to save your videos as standard Powerpoint files in case you need to make modification. It is suggested that you export the final version of the video into an MP4. This will solve most Mac-PC incompatibilities and problems associated with different Powerpoint versions. If you have a choice of resolution, choose the lowest resolution. Videos can also be saved as YouTube videos. Be care of loss in image resolution when converting videos to YouTube format. Videos can be stored as cloud files, in which case the URLs must be submitted to provide access to the files.


How to submit essays/videos

·         The rough draft and final version of each case study must be submit via its separate Assignment link. The instructor will provide comments on the rough draft and the grade and comments for the final vesion in Canvas.

·         Essay and video files can submitted as attachments. Alternatively, URLs for cloud-stored files can be provided.


·         A separate Discussion page will be provided in Canvas for submission of the final version of each case study. All essays and videos placed in a Discussion page can be accessed by all students.



Plant Pathology: Principles and Applications