PCA PLANT PATHOGENS EXAM 2025 | ALL QUESTIONS AND
CORRECT ANSWERS | NEWEST EXAM | GRADED A+ | VERIFIED
ANSWERS (JUST RELEASED)
Plant Disease Definition - (CORRECT ANSWER)Abnormal physiological processes caused by a causal
pathogen
Economic significance of plant diseases - (CORRECT ANSWER)Losses of yield, crops, inputs, land
Pathogen - (CORRECT ANSWER)Causal agent of disease
Signs of disease - (CORRECT ANSWER)Structures of the pathogen
Symptoms of disease - (CORRECT ANSWER)Plant response to pathogen infection
Abiotic factors of plant disease - (CORRECT ANSWER)Air pollution, temperature, nutrients
Biotic factors of plant disease - (CORRECT ANSWER)Living organisms (fungi, bacteria, viruses)
Obligate parasite - (CORRECT ANSWER)unable to grow outside of a living host
Facultative saprophyte - (CORRECT ANSWER)prefers living organic matter as a source of nutrition but
can adapt to the use of dead organic matter under certain conditions
Facultative parasite - (CORRECT ANSWER)A pathogen that prefers dead inorganic material, but can also
obtain nourishment from living organic material
Biotroph - (CORRECT ANSWER)Any parasite that cannot survive in a dead host and therefore keeps it
alive
1
,Necrotroph - (CORRECT ANSWER)Parasite that kills host cells
Koch's Postulates - (CORRECT ANSWER)series of guidelines used to identify the microorganism that
causes a specific disease
Three components of disease triangle - (CORRECT ANSWER)Causal agent, environment, host
Role of each component of disease triangle - (CORRECT ANSWER)All three must be present for disease
to occur. Environment must favor causal agent. Host must favor causal agent.
How humans impact each component of disease triangle - (CORRECT ANSWER)Manipulate the
environment, host-plant resistance, preventative/suppressive/erradicative pesticides
Impact of epidemic when one component of disease triangle does not come into contact with the other
two components - (CORRECT ANSWER)Slows epidemic to a halt. Disease spread needs all three
components interacting
Management strategy to break environment component - (CORRECT ANSWER)Alter planting dates,
remove alternative hosts, alter harvest
Management strategy to break host component - (CORRECT ANSWER)Alternate crop, host-plant
resistance
Management strategy to break causal agent component - (CORRECT ANSWER)Pesticide applications
How can knowledge of plant disease triangle be used in diagnosis? - (CORRECT ANSWER)Can rule out
different pathogens based on host and environment.
2
,Epidemiology - (CORRECT ANSWER)Branch of medical science concerned with the incidence,
distribution, and control of diseases that affect large numbers of people.
Environmental factors that affect epidemics - (CORRECT ANSWER)Temperature, humidity, moisture, soil
pH, nutrient availability, air movement
Importance of time in the development of an epidemic - (CORRECT ANSWER)Epidemics develop very
quickly if conditions are favorable. It is critical to reduce the rate of infection during susceptible life
stages of the plant
How does type of reproduction cycle affect development of an epidemic - (CORRECT ANSWER)Polycyclic
epidemics can develop much more rapidly than monocyclic epidemics because of secondary inoculum
production.
How does dissemination affect development of an epidemic - (CORRECT ANSWER)Conditions that
increase dissemination will accelerate development of epidemics
Monocyclic disease - (CORRECT ANSWER)Disease that only has a primary infection cycle
Polycyclic disease - (CORRECT ANSWER)Disease that produces a secondary inoculum, and has a
secondary infection cycle in addition to a primary infection cycle
Why are monocyclic diseases less likely to result in serious epidemics? - (CORRECT ANSWER)Controlling
primary inoculum is much easier than controlling primary and secondary inoculum. Once primary
inoculum is controlled and dissemination is controlled, the disease essentially stops developing.
How do sanitation practices impact monocyclic diseases? - (CORRECT ANSWER)Epidemic may be
delayed, but severe epidemic can still occur if environmental conditions are favorable for disease
development
3
, How do sanitation practices impact polycyclic diseases? - (CORRECT ANSWER)Reducing primary
inoculum may reduce the amount of secondary inoculum produced. If rate of infection is high, there is
little effect. But if rate of infection is low, it may reduce an epidemic
Formae specialis - (CORRECT ANSWER)Indicates a fungus is adapted to a specific host
Incubation period - (CORRECT ANSWER)interval between initial infection and first signs and symptoms
Infection - (CORRECT ANSWER)Invasion of a plant by a pathogen
Infestation - (CORRECT ANSWER)Large numbers of pathogen present causing damage
Inoculum - (CORRECT ANSWER)Infecting agent of a pathogen
Latent infection - (CORRECT ANSWER)infection in which the infectious agent is present but not causing
symptoms
Mummy - (CORRECT ANSWER)Dead, shriveled fruit that a pathogen may overwinter in
Overwintering - (CORRECT ANSWER)the process by which some organisms pass through or wait out the
winter season
Pathovar - (CORRECT ANSWER)subdivision of a plant pathogenic bacterial species defined by host range
Propagule - (CORRECT ANSWER)Portion of a plant which is used to generate a new plant
Race - (CORRECT ANSWER)Strain of a virus adapted to a specific host
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CORRECT ANSWERS | NEWEST EXAM | GRADED A+ | VERIFIED
ANSWERS (JUST RELEASED)
Plant Disease Definition - (CORRECT ANSWER)Abnormal physiological processes caused by a causal
pathogen
Economic significance of plant diseases - (CORRECT ANSWER)Losses of yield, crops, inputs, land
Pathogen - (CORRECT ANSWER)Causal agent of disease
Signs of disease - (CORRECT ANSWER)Structures of the pathogen
Symptoms of disease - (CORRECT ANSWER)Plant response to pathogen infection
Abiotic factors of plant disease - (CORRECT ANSWER)Air pollution, temperature, nutrients
Biotic factors of plant disease - (CORRECT ANSWER)Living organisms (fungi, bacteria, viruses)
Obligate parasite - (CORRECT ANSWER)unable to grow outside of a living host
Facultative saprophyte - (CORRECT ANSWER)prefers living organic matter as a source of nutrition but
can adapt to the use of dead organic matter under certain conditions
Facultative parasite - (CORRECT ANSWER)A pathogen that prefers dead inorganic material, but can also
obtain nourishment from living organic material
Biotroph - (CORRECT ANSWER)Any parasite that cannot survive in a dead host and therefore keeps it
alive
1
,Necrotroph - (CORRECT ANSWER)Parasite that kills host cells
Koch's Postulates - (CORRECT ANSWER)series of guidelines used to identify the microorganism that
causes a specific disease
Three components of disease triangle - (CORRECT ANSWER)Causal agent, environment, host
Role of each component of disease triangle - (CORRECT ANSWER)All three must be present for disease
to occur. Environment must favor causal agent. Host must favor causal agent.
How humans impact each component of disease triangle - (CORRECT ANSWER)Manipulate the
environment, host-plant resistance, preventative/suppressive/erradicative pesticides
Impact of epidemic when one component of disease triangle does not come into contact with the other
two components - (CORRECT ANSWER)Slows epidemic to a halt. Disease spread needs all three
components interacting
Management strategy to break environment component - (CORRECT ANSWER)Alter planting dates,
remove alternative hosts, alter harvest
Management strategy to break host component - (CORRECT ANSWER)Alternate crop, host-plant
resistance
Management strategy to break causal agent component - (CORRECT ANSWER)Pesticide applications
How can knowledge of plant disease triangle be used in diagnosis? - (CORRECT ANSWER)Can rule out
different pathogens based on host and environment.
2
,Epidemiology - (CORRECT ANSWER)Branch of medical science concerned with the incidence,
distribution, and control of diseases that affect large numbers of people.
Environmental factors that affect epidemics - (CORRECT ANSWER)Temperature, humidity, moisture, soil
pH, nutrient availability, air movement
Importance of time in the development of an epidemic - (CORRECT ANSWER)Epidemics develop very
quickly if conditions are favorable. It is critical to reduce the rate of infection during susceptible life
stages of the plant
How does type of reproduction cycle affect development of an epidemic - (CORRECT ANSWER)Polycyclic
epidemics can develop much more rapidly than monocyclic epidemics because of secondary inoculum
production.
How does dissemination affect development of an epidemic - (CORRECT ANSWER)Conditions that
increase dissemination will accelerate development of epidemics
Monocyclic disease - (CORRECT ANSWER)Disease that only has a primary infection cycle
Polycyclic disease - (CORRECT ANSWER)Disease that produces a secondary inoculum, and has a
secondary infection cycle in addition to a primary infection cycle
Why are monocyclic diseases less likely to result in serious epidemics? - (CORRECT ANSWER)Controlling
primary inoculum is much easier than controlling primary and secondary inoculum. Once primary
inoculum is controlled and dissemination is controlled, the disease essentially stops developing.
How do sanitation practices impact monocyclic diseases? - (CORRECT ANSWER)Epidemic may be
delayed, but severe epidemic can still occur if environmental conditions are favorable for disease
development
3
, How do sanitation practices impact polycyclic diseases? - (CORRECT ANSWER)Reducing primary
inoculum may reduce the amount of secondary inoculum produced. If rate of infection is high, there is
little effect. But if rate of infection is low, it may reduce an epidemic
Formae specialis - (CORRECT ANSWER)Indicates a fungus is adapted to a specific host
Incubation period - (CORRECT ANSWER)interval between initial infection and first signs and symptoms
Infection - (CORRECT ANSWER)Invasion of a plant by a pathogen
Infestation - (CORRECT ANSWER)Large numbers of pathogen present causing damage
Inoculum - (CORRECT ANSWER)Infecting agent of a pathogen
Latent infection - (CORRECT ANSWER)infection in which the infectious agent is present but not causing
symptoms
Mummy - (CORRECT ANSWER)Dead, shriveled fruit that a pathogen may overwinter in
Overwintering - (CORRECT ANSWER)the process by which some organisms pass through or wait out the
winter season
Pathovar - (CORRECT ANSWER)subdivision of a plant pathogenic bacterial species defined by host range
Propagule - (CORRECT ANSWER)Portion of a plant which is used to generate a new plant
Race - (CORRECT ANSWER)Strain of a virus adapted to a specific host
4
