PCA PLANT PATHOGENS EXAM 2025 | ALL QUESTIONS AND
CORRECT ANSWERS | NEWEST EXAM | GRADED A+ | VERIFIED
ANSWERS (JUST RELEASED)
Plant disease - (CORRECT ANSWER)Abnormal physiological processes caused by a causal pathogen
What is the economical significance of plant disease - (CORRECT ANSWER)Losses of yields, crops, inputs,
and land
Pathogen - (CORRECT ANSWER)a causal agent of the disease
Disease - (CORRECT ANSWER)an abnormal condition that causes issues like declined health or death of a
plant
Sign - (CORRECT ANSWER)the presence of a structure of a pathogen (spore, mycelium, or even mold
growth)
Symptom - (CORRECT ANSWER)a plant response to a pathogen infection (decline of growth, vigor, or
even death)
What are some abiotic factors that cause plant diseases - (CORRECT ANSWER)
What are some biotic factors that cause plant diseases - (CORRECT ANSWER)
Obligate parasite - (CORRECT ANSWER)Unable to grow outside of a living host (viruses)
Facultative saprophytes - (CORRECT ANSWER)prefers living organic matter as a source of nutrition but
can adapt to the use of dead organic matter under certain conditions (phytophthora)
Facultative parasites - (CORRECT ANSWER)a pathogen that prefers dead inorganic material, but can also
obtain nourishment from living organic material (bacteria)
1
,Biotrophic - (CORRECT ANSWER)Any parasite that cannot survive in a dead host and therefore keeps it
alive
Necrotrophic - (CORRECT ANSWER)parasites that kill the host cells
Kotch postulates - (CORRECT ANSWER)A series or guidelines used to identify the microorganism that
causes a specific disease
What are the three components of plant disease triangle - (CORRECT ANSWER)the environment, the
host, and the causal agent
What is the role of each of the component of the disease triangle - (CORRECT ANSWER)All three must be
present in order for infection to take place, the environment must favor the causal agent and the host
must be susceptible to the causal agent
How do humans impact the disease triangle - (CORRECT ANSWER)Humans can manipulate the
environment, plant host resistant varieties, and use preventative/suppressive/eradicative pesticides all
to change a piece of the disease triangle
How does one component of the triangle impact a epidemic if it does not come into contact with the
other two - (CORRECT ANSWER)If one component of the plant disease triangle is missing the epidemic
will slow to a halt, in order for the disease to spread it must have all three parts of the triangle
How can you break the environment portion of the disease triangle - (CORRECT ANSWER)alter planting
dates, remove alternative host, alter harvest dates
How can you break the host portion of the disease triangle - (CORRECT ANSWER)alternate crop, plant
host resistance species
2
, How can you break the causal agent portion of the disease triangle - (CORRECT ANSWER)Pesticide
application
How does the disease triangle help in diagnosis - (CORRECT ANSWER)If you understand the plant disease
triangle you can use the host species and environment of a area where the crop is planted to rule out
different pathogens
Epidemiology - (CORRECT ANSWER)Branch of medical science concerned with the incidence,
distribution, and control of disease that affect large numbers of people or hosts
List the environmental factors that affect epidemics and explain how they do so - (CORRECT
ANSWER)Temperature, humidity, moisture, soil pH, nutrient availability, and air movement
Describe the importance of time in the development of an epidemic - (CORRECT ANSWER)Epidemics
develop quickly if conditions are favorable. It is critical to reduce the rate of infection during susceptible
life stages of the plant
How does type reproduction affect the 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 the development of an epidemic - (CORRECT ANSWER)conditions that
increase dissemination will accelerate development of epidemics
Single (annual) cycle (monocyclic disease - (CORRECT ANSWER)Diseases that only have a primary
infection cycle
multiple cycle (polycyclic) disease - (CORRECT ANSWER)Disease that produce a secondary inoculum, and
has a secondary infection cycle in addition to the primary infection cycle
3
CORRECT ANSWERS | NEWEST EXAM | GRADED A+ | VERIFIED
ANSWERS (JUST RELEASED)
Plant disease - (CORRECT ANSWER)Abnormal physiological processes caused by a causal pathogen
What is the economical significance of plant disease - (CORRECT ANSWER)Losses of yields, crops, inputs,
and land
Pathogen - (CORRECT ANSWER)a causal agent of the disease
Disease - (CORRECT ANSWER)an abnormal condition that causes issues like declined health or death of a
plant
Sign - (CORRECT ANSWER)the presence of a structure of a pathogen (spore, mycelium, or even mold
growth)
Symptom - (CORRECT ANSWER)a plant response to a pathogen infection (decline of growth, vigor, or
even death)
What are some abiotic factors that cause plant diseases - (CORRECT ANSWER)
What are some biotic factors that cause plant diseases - (CORRECT ANSWER)
Obligate parasite - (CORRECT ANSWER)Unable to grow outside of a living host (viruses)
Facultative saprophytes - (CORRECT ANSWER)prefers living organic matter as a source of nutrition but
can adapt to the use of dead organic matter under certain conditions (phytophthora)
Facultative parasites - (CORRECT ANSWER)a pathogen that prefers dead inorganic material, but can also
obtain nourishment from living organic material (bacteria)
1
,Biotrophic - (CORRECT ANSWER)Any parasite that cannot survive in a dead host and therefore keeps it
alive
Necrotrophic - (CORRECT ANSWER)parasites that kill the host cells
Kotch postulates - (CORRECT ANSWER)A series or guidelines used to identify the microorganism that
causes a specific disease
What are the three components of plant disease triangle - (CORRECT ANSWER)the environment, the
host, and the causal agent
What is the role of each of the component of the disease triangle - (CORRECT ANSWER)All three must be
present in order for infection to take place, the environment must favor the causal agent and the host
must be susceptible to the causal agent
How do humans impact the disease triangle - (CORRECT ANSWER)Humans can manipulate the
environment, plant host resistant varieties, and use preventative/suppressive/eradicative pesticides all
to change a piece of the disease triangle
How does one component of the triangle impact a epidemic if it does not come into contact with the
other two - (CORRECT ANSWER)If one component of the plant disease triangle is missing the epidemic
will slow to a halt, in order for the disease to spread it must have all three parts of the triangle
How can you break the environment portion of the disease triangle - (CORRECT ANSWER)alter planting
dates, remove alternative host, alter harvest dates
How can you break the host portion of the disease triangle - (CORRECT ANSWER)alternate crop, plant
host resistance species
2
, How can you break the causal agent portion of the disease triangle - (CORRECT ANSWER)Pesticide
application
How does the disease triangle help in diagnosis - (CORRECT ANSWER)If you understand the plant disease
triangle you can use the host species and environment of a area where the crop is planted to rule out
different pathogens
Epidemiology - (CORRECT ANSWER)Branch of medical science concerned with the incidence,
distribution, and control of disease that affect large numbers of people or hosts
List the environmental factors that affect epidemics and explain how they do so - (CORRECT
ANSWER)Temperature, humidity, moisture, soil pH, nutrient availability, and air movement
Describe the importance of time in the development of an epidemic - (CORRECT ANSWER)Epidemics
develop quickly if conditions are favorable. It is critical to reduce the rate of infection during susceptible
life stages of the plant
How does type reproduction affect the 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 the development of an epidemic - (CORRECT ANSWER)conditions that
increase dissemination will accelerate development of epidemics
Single (annual) cycle (monocyclic disease - (CORRECT ANSWER)Diseases that only have a primary
infection cycle
multiple cycle (polycyclic) disease - (CORRECT ANSWER)Disease that produce a secondary inoculum, and
has a secondary infection cycle in addition to the primary infection cycle
3
