PCA - Plant Pathogens Exam Questions and Well
Detailed Answers(100% correct) LATEST UPDATE
2025/26
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)
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
How can you break the causal agent portion of the disease triangle -CORRECT
ANSWER Pesticide application
Detailed Answers(100% correct) LATEST UPDATE
2025/26
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)
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
How can you break the causal agent portion of the disease triangle -CORRECT
ANSWER Pesticide application
