PCA PLANT PATHOGENS EXAMINATION TEST
2026 QUESTIONS AND SOLUTIONS 100%
CORRECT
◉ Economic significance of plant diseases. Answer: Losses of yield,
crops, inputs, land
◉ Pathogen. Answer: Causal agent of disease
◉ Signs of disease. Answer: Structures of the pathogen
◉ Symptoms of disease. Answer: Plant response to pathogen infection
◉ Abiotic factors of plant disease. Answer: Air pollution, temperature,
nutrients
◉ Biotic factors of plant disease. Answer: Living organisms (fungi,
bacteria, viruses)
◉ Obligate parasite. Answer: unable to grow outside of a living host
,◉ Facultative saprophyte. 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. Answer: A pathogen that prefers dead inorganic
material, but can also obtain nourishment from living organic material
◉ Biotroph. Answer: Any parasite that cannot survive in a dead host and
therefore keeps it alive
◉ Necrotroph. Answer: Parasite that kills host cells
◉ Koch's Postulates. Answer: series of guidelines used to identify the
microorganism that causes a specific disease
◉ Three components of disease triangle. Answer: Causal agent,
environment, host
◉ Role of each component of disease triangle. 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. 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. Answer: Slows
epidemic to a halt. Disease spread needs all three components interacting
◉ Management strategy to break environment component. Answer:
Alter planting dates, remove alternative hosts, alter harvest
◉ Management strategy to break host component. Answer: Alternate
crop, host-plant resistance
◉ Management strategy to break causal agent component. Answer:
Pesticide applications
◉ How can knowledge of plant disease triangle be used in diagnosis?.
Answer: Can rule out different pathogens based on host and
environment.
◉ Epidemiology. 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. Answer: Temperature,
humidity, moisture, soil pH, nutrient availability, air movement
, ◉ Importance of time in the development of an epidemic. 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. Answer: Polycyclic epidemics can develop much more rapidly
than monocyclic epidemics because of secondary inoculum production.
◉ How does dissemination affect development of an epidemic. Answer:
Conditions that increase dissemination will accelerate development of
epidemics
◉ Monocyclic disease. Answer: Disease that only has a primary
infection cycle
◉ Polycyclic disease. 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?. 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.
2026 QUESTIONS AND SOLUTIONS 100%
CORRECT
◉ Economic significance of plant diseases. Answer: Losses of yield,
crops, inputs, land
◉ Pathogen. Answer: Causal agent of disease
◉ Signs of disease. Answer: Structures of the pathogen
◉ Symptoms of disease. Answer: Plant response to pathogen infection
◉ Abiotic factors of plant disease. Answer: Air pollution, temperature,
nutrients
◉ Biotic factors of plant disease. Answer: Living organisms (fungi,
bacteria, viruses)
◉ Obligate parasite. Answer: unable to grow outside of a living host
,◉ Facultative saprophyte. 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. Answer: A pathogen that prefers dead inorganic
material, but can also obtain nourishment from living organic material
◉ Biotroph. Answer: Any parasite that cannot survive in a dead host and
therefore keeps it alive
◉ Necrotroph. Answer: Parasite that kills host cells
◉ Koch's Postulates. Answer: series of guidelines used to identify the
microorganism that causes a specific disease
◉ Three components of disease triangle. Answer: Causal agent,
environment, host
◉ Role of each component of disease triangle. 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. 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. Answer: Slows
epidemic to a halt. Disease spread needs all three components interacting
◉ Management strategy to break environment component. Answer:
Alter planting dates, remove alternative hosts, alter harvest
◉ Management strategy to break host component. Answer: Alternate
crop, host-plant resistance
◉ Management strategy to break causal agent component. Answer:
Pesticide applications
◉ How can knowledge of plant disease triangle be used in diagnosis?.
Answer: Can rule out different pathogens based on host and
environment.
◉ Epidemiology. 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. Answer: Temperature,
humidity, moisture, soil pH, nutrient availability, air movement
, ◉ Importance of time in the development of an epidemic. 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. Answer: Polycyclic epidemics can develop much more rapidly
than monocyclic epidemics because of secondary inoculum production.
◉ How does dissemination affect development of an epidemic. Answer:
Conditions that increase dissemination will accelerate development of
epidemics
◉ Monocyclic disease. Answer: Disease that only has a primary
infection cycle
◉ Polycyclic disease. 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?. 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.
