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20 Cards in this Set

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  • Back
Draw the disease triangle.
you must have all 3 to have a plant disease
What is the importance of plant diseases?
1) reduces quantity and quality of plant produce
2) limits the kinds of plants and area industries
3) makes plants poisonous to humans and animals
4) causes financial losses
What is the geographic impact of plant disease?
Africa has the highest impact with almost 50% of produce lost, with Asia second, then S. America
What is plant pathology?
logos=study of
What is plant disease?
The series of invisible and visible responses of plant cells and tissues to a pathogenic organism or environmental factor that result in adverse changes in the form, function or integrity of the plant and may lead to a partial impairment or death of plant parts or entire plant
What is a symptom?
indication of disease by a reaction of host
What is a sign?
indication of disases from the direct observation of a pathogen or its parts
What are some biotic causes of plant diseases?
fungi, bacteria, viruses and viroids, nematodes, protozoa
What are some abiotic causes of plant diseases?
heat, drought, mineral toxicities, nutritional deficiencies, excess moisture
What are examples of symptoms?
root rot, gall, wilt, leaf spot, lesion, canker, blight
What are examples of signs?
Fungi--mycelium, spores, sclerotia
Nematode--eggs, juveniles, adults
Viruses--inclusions, virus particles
What are Koch's postulates?
1. Suspect causal agent must be present in all diseased specimen.
2. Isolate pathogen.
3. Inoculate healthy host.
4. Reisolate.
Explain 3 past plant disease epidemics.
1) Rust epidemic-rust on wheat and barley in 2000-700 BC and people offered prayers and sacrifices for it to end.
2) Ergot epidemics-on rye, caused hallucinations, Salem witch trials, St. Anthony's Fire
3) Chestnut blight
List 3 current plant disease epidemics.
1) sudden oak death
2) citrus canker
3) lethal yellowing of coconut palms
What was spontaneous generation?
microorganisms and their spores were the result rather than the cause of disease
Who was Anton deBary?
Father of Plant Pathology b/c he proved that potato late blight was caused by a fungus
What is the germ theory?
microorganisms were produced from pre-existing microorganisms and that most infectious diseases were caused by germs
Who created the germ theory of disease?
Louis Pasteur
Who developed artificial media for culturing microorganisms?
What did Koch do?
Established the postulates for demonstrating that a microorganism was the cause of a particulat disease using Anthrax bacilli