Exam 1 Flashcards
Define phytopathology.
Study of plant suffering
Three F’s for studying plant suffering?
Food, fuel, fiber
Which interaction has 0 effect on either species?
Neutralism
Which interaction negatively affects species 1 and 0 effect on species 2? (one inhibits the other)
Ammensalism
Which interaction has a positive effect on species 1 and 0 effect on species 2?
Commensalism
Which interaction is favorable to both species, but not obligatory?
Synergism
Which interaction is favorable to both and obligatory?
Mutualism
Which interaction is negative to both and mutually inhibitory?
Competition
Which interaction is negative to species 1 and positive to species 2 (one feeds on another?)
Predation
Which interaction is negative to species 1 and positive to species 2 (one lives in intimate contact with the other, deriving nutrients?)
Parasitism
The relationship of parasite to host is _____ only.
Nutritional
Pathogens get ____ from the host, but also cause ____.
Nutrients; disease
Any malfunctioning of host cells and tissues that results from continuous irritation by a pathogenic agent or environmental factor and leads to the development of symptoms?
Disease
Short-term, mechanical abnormality
Damage
Long-term, disturbance of plant metabolism caused by pathogens
Disease
Two primary causes of disease
Biotic/Abiotic
Alterations in the host caused by disease, progressing over time and characteristic of a particular disease
Symptoms
3 factors of the disease triangle
Susceptible host, pathogen, conducive environment
Biotrophs feed on…
living things
Necrotrophs feed on…
dead thing
Semi-biotrophs are a…
mixture of both
Hemibiotrophs…
spend part of their life cycle as biotrops and part as necrotrophs
Which lifestyle requires a living host to grow and reproduce, do not compete in the environment and usually cannot be grown in pure culture? (They are obligate parasites).
Biotrophs
Which lifestyle feeds primarily on dead organic matter but can also colonize living tissue, kills cells before feeding on them, and often produces toxins? (Facultative parasites, opportunistic pathogens)
Necrotrophs
Which lifestyle primarily feeds on living hosts, but are also capable of living in dead host tissue/other organic matter? They may have a two-stage life cycle and are facultative saprotrophs.
Semi-biotrophs or hemibiotrophs
Has the ability to eat decaying things
saprotroph
Strong saprotrophs, weak pathogens, necrotrophs
Soil inhabitants
Weak saprotrophs, strong pathogens, biotrophs
Soil survivors
Uses signs, symptoms and tests for presence of a pathogen to identify a disease or other problem. It relies on existing knowledge and is not proof.
Diagnosis
Which plant malfunction category? Nutrient deficiency Nutrient toxicity Water imbalance Wind Hail Sunburn Frost damage Lightening Chemical
Abiotic
Which plant malfunction category? Insects Mites Browsing/grazing Burrowing Marking Urination
Pests
Which plant malfunction category? Bacteria Fungi Stramenopiles Plasmodia Nematodes Viruses
Parasites and pathogens
Approximately ___% of plant problems are abiotic.
50
How to distinguish abiotic from biotic? 5 things
What does normal look like? Symptom pattern? Environmental history? Soil characteristics? Weather?
Blossom end rot is caused b a deficiency in ____.
Calcium
Nutrient toxicity can mimic ______.
Pathogenic agents
Girdling, root damage, soil compaction
Examples of physical damage
4 Challenges in identifying plant diseases
Inadequate information
Pathogen absent
Multiple possible problems match symptoms
Multiple problems present
Diagnosis or proof?
Based on associations and confidence levels vary
Diagnosis
Diagnosis or proof?
Defined series of steps to demonstrate pathogenicity (Koch’s postulates)
Proof
Birth of agriculture was ~_____ BCE and was primarily ______ in the ______
10,000; Wheat/barley; fertile crescent.
Which plant disease contributed to the fall of the Roman Empire?
Wheat rust
Wheat rust is caused by which pathogen? What kind of pathogen is it?
Puccinia graminis (fungus)
Puccinia graminis: Biotroph or necrotroph?
Biotroph
Who described crop devastation in ~350 BCE?
Aristotle
Who provided a meticulous description of rust disease?
Theophrastus
Who is the deity of cereal rust in Roman times?
Robigus
What fungal pathogen causes Ergot of Rye?
Claviceps purpurea
What disease causes delusions/hallucinations and also burning sensations?
Ergotism (Holy Fire)
St. Anthony’s Fire referenced what disease?
Holy Fire (Hospital dedicated to disease)
Who linked Ergotism to rye?
Thuillier
Who produced 1st mass produced microscopes?
Van Leeuwehoek
Who started taxonomy of living things?
Robert Hook
3 men of Germ Theory
Pasteur, Koch, deBary
Who disproved spontaneous generation?
Pasteur
4 Koch’s Postulates
- Organism found in diseased but not healthy hosts.
- Isolate organism in pure culture
- Culture causes same disease when introduced int healthy hosts
- Same organism can be isolated from second host
Potatoes are native to…
South America
Potato Blight Years
1845-1860
Who proved pathogenicity of late potato blight using Koch’s postulates?
Anton deBary
Which pathogen causes late potato blight?
Phytophthora infestans
Name the disease:
Cankers on branches and trunk, wilting and death, resprouting from base
Chestnut blight; cryphonectria parasitica
6 Steps of Disease Cycle
Inoculation Attachment Penetration Infection Colonization & Growth Reproduction & Dissemination
3 most common methods of pathogen dispersal
Wind, water, vectors
Which stage of the disease cycle?
Introduction of pathogen onto susceptible host tissue
Inoculation
infective unit of a pathogen
inoculum
Inoculum produced on dormant structure that survives unfavorable season; causes initial infections at start of growing season
Primary inoculum
Inoculum produced on host plant from primary infections; causes secondary infections throughout growing season
Secondary inoculum
Which stage of the disease cycle?
Recognition of the host; production of adhesives and surface-degrading enzymes; pertains to bacteria, fungi, parasitic plants
Attachment
Time spent on the surface of the host before penetration
Incubation
Which stage of the disease cycle?
Germ tube formation and extension; creates opening into plant (directly, naturally, through wounds or vectors)
Penetration
