Plant Pathology 200

This Week's Major Concept is non-living disease agents. Although we have focused on plant diseases caused by pathogenic organisms, many plant diseases are caused by non-living factors. These abiotic diseases are non-infectious, not able to spread from one plant to another, and probably occur more often than do biotic diseases.

This Week's Point of Confusion is the difference between a disease and an injury. PODCAST: pppodcastweek13.mp3

This Week's Major Concept is VIRUSES. Viruses are the smallest pathogens that we study in Plant Pathology 200. These particles are measured in nanometers, or billionths of a meter. Some scientists consider viruses to be the smallest living pathogens, while others do not think of them as alive, but rather as complex macromolecules.

This Week's Point of Confusion is the difference between symptoms and signs of plant disease. PODCAST: pppodcastweek12.mp3

This Week's Major Concept is VECTORS. Any living organism - including insects, animals, fungi, nematodes, and human beings - that is able to transmit a pathogen and disseminate a disease is called a vector.

This Week's Point of Confusion is management strategies for Dutch elm disease and chestnut blight. PODCAST: pppodcastweek11.mp3

The Major Concept for this week is the difference between autoecious and heteroecious rust life cycles. Of all the plant pathogenic organisms, the rust fungi have some of the most complex and interesting disease cycles.

This Week's Point of Confusion is the difference between primary and secondary inoculum. PODCAST: pppodcastweek10.mp3

The Major Issue for this week is mycotoxins. Chemicals produced by fungi that are harmful to humans and other animals are called mycotoxins. Mycotoxins can be present in our food without us knowing it because many of them are colorless, odorless and tasteless, yet the presence of these substances can make those who consume them very ill.

This Week's Point of Confusion is the difference between mycotoxins and the fungi that produce them. PODCAST: pppodcastweek9.mp3

The Major Concept for this week is NEMATODES. Nematodes are non-segmented roundworms, most of them so slender that they are typically invisible to the naked eye. Being members of the animal kingdom, nematodes are eukaryotic, multicellular, and heterotrophic.

This Week's Point of Confusion is the difference between the terms genetic diversity and monoculture. PODCAST: pppodcastweek8.mp3

The Major Issue for this week is human use of pesticides. A pesticide is a chemical or mixture of chemicals used to prevent, eliminate or control unwanted animals, plants or microorganisms. Fungicides are one class of pesticides used to manage plant diseases.

This Week's Point of Confusion is the various ways in which fungicides can be categorized. PODCAST: pppodcastweek7.mp3

The Major Issue for this week is exotic vs. endemic pathogens. Many of the plant disease epidemics that we have studied so far have been the result of introducing a new pathogen into an area where it did not exist before. We call these exotic diseases. However, not all plant diseases are the result of a new pathogen or new host being introduced to an area. Endemic plants are infected by endemic pathogens all of the time.

This Week's Point of Confusion is the difference between monocyclic and polycyclic disease cycles. PODCAST: pppodcastweek6.mp3

A former PLPA 200 student, Bryan Anderson, created this podcast as part of a James Scholar Project

The Major Concept for this podcast is the CENTRAL DOGMA of genetics. Genetics is the study of how traits are passed down from one generation to the next. The basis of genetics is the macromolecule called deoxyribonucleic acid, or DNA. PODCAST: pppodcast - the central dogma.mp3

The Major Concept for this week is genetically modified organisms or GMOs. A genetically modified organism is any organism whose genetic material has been altered using enzymes and laboratory techniques that are generally known as recombinant DNA technology. Animals, plants, and microbes that are GMOs have been developed and are being used in many applications around the world.

This Week's Point of Confusion is the central dogma. The central dogma of biology describes the processes by which information is both maintained and expressed in a cell. PODCAST: pppodcastweek5.mp3

PLPA 200 student Jackie Rutter created this podcast as part of an honors project for PLPA 200.

The Major Concept for this podcast is binary fission. Binary fission is the process by which bacterial cells reproduce. The process of binary fission has some similarities and some differences with the reproduction processes used by eukaryotic organisms.

The point of confusion for this podcast is the difference between signs and symptoms of plant diseases. PODCAST: pppodcast - binary fission.mp3

The Major Concept for this week is the bacteria. Bacteria are tiny, single-celled organisms, in contrast to fungi, plants and animals, which are all multicellular. A single bacterium is smaller than the spores produced by fungi.

This Week's Point of Confusion is the term inoculum. For any plant disease, inoculum must be present to initiate the first, or primary, disease cycle as well as any subsequent, or secondary, disease cycles. PODCAST: pppodcastweek4.mp3

The Major Concept for this week is the role of people in spreading plant diseases. In order for a plant disease to spread plant pathogens have had to evolve various methods for moving from an infected plant to a healthy one. With the advent of agriculture, humans became a very effective means for moving plant pathogens both short and long distances.

This Week's Point of Confusion concerns the classification of fungi into different fungal groups. Just like plants and animals, fungi have been classified into groups based on their characteristics. PODCAST: pppodcastweek3.mp3

The Major Concept for this week is THE FUNGI. Just what are fungi, and how do fungi differ from other forms of life? Although fungi have similarities with both plants and animals, they are distinct organisms that do not belong in either the plant or animal kingdoms.

This Week's Point of Confusion relates to the fact that fungi can reproduce both sexually and asexually. Fungi use both sexual and asexual forms of reproduction. In fact the same fungus can produce both sexual and asexual spores, depending on the environmental conditions. Sexual and asexual spores can serve different functions in the disease cycle of a fungal pathogen. PODCAST: pppodcastweek2.mp3

Welcome to the Plants, Pathogens, and People Podcasts! Each weekly podcast will review a major concept or issue that will be discussed in class, will clarify a possible point of confusion, and will provide study hints that may be useful as you study for quizzes and the final exam.

The Major Concept for this week is the plant disease triangle. The plant disease triangle is a diagrammatic representation of the three fundamental elements required for disease: a susceptible plant, a pathogen capable of causing disease, and a favorable environment. If any of these three elements is missing, no disease occurs.

This Week's Point of Confusion is the difference between the terms pathogen and disease. It is important to differentiate between a pathogen and a disease and NOT to use these two terms as synonyms. PODCAST: pppodcastweek1.mp3