PCA - Plant Pathogens Exam 2026 Question
and Answer | Real Questions and Answers |
A+ Verified
• 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
• 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.
• 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
• 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
and Answer | Real Questions and Answers |
A+ Verified
• 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
• 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.
• 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
• 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
