PCA - Plant Pathogens Exam Questions and Answers 2025
Plant Disease Definition Abnormal physiological processes caused by a causal pathogen
Economic significance of plant
diseases Losses of yield, crops, inputs, land
Pathogen Causal agent of disease
Signs of disease Structures of the pathogen
Symptoms of disease Plant response to pathogen infection
Abiotic factors of plant disease Air pollution, temperature, nutrients
Biotic factors of plant disease Living organisms (fungi, bacteria, viruses)
Obligate parasite unable to grow outside of a living host
prefers living organic matter as a source of nutrition but can adapt
to the use of
Facultative saprophyte
dead organic matter under certain conditions
A pathogen that prefers dead inorganic material, but can also
obtain nourishment
Facultative parasite
from living organic material
Any parasite that cannot survive in a dead host and therefore
Biotroph keeps it alive
Necrotroph Parasite that kills host cells
series of guidelines used to identify the microorganism that causes
Koch's Postulates a specific disease
Three components of disease
triangle Causal agent, environment, host
Role of each component of All three must be present for disease to occur. Environment must
disease favor causal agent.
triangle Host must favor causal agent.
How humans impact each
component of Manipulate the environment, host-plant resistance,
disease triangle preventative/suppressive/erradicative pesticides
Impact of epidemic when one Slows epidemic to a halt. Disease spread needs all three
component components interacting
of disease triangle does not
, come into
contact with the other two
components
Plant Disease Definition Abnormal physiological processes caused by a causal pathogen
Economic significance of plant
diseases Losses of yield, crops, inputs, land
Pathogen Causal agent of disease
Signs of disease Structures of the pathogen
Symptoms of disease Plant response to pathogen infection
Abiotic factors of plant disease Air pollution, temperature, nutrients
Biotic factors of plant disease Living organisms (fungi, bacteria, viruses)
Obligate parasite unable to grow outside of a living host
prefers living organic matter as a source of nutrition but can adapt
to the use of
Facultative saprophyte
dead organic matter under certain conditions
A pathogen that prefers dead inorganic material, but can also
obtain nourishment
Facultative parasite
from living organic material
Any parasite that cannot survive in a dead host and therefore
Biotroph keeps it alive
Necrotroph Parasite that kills host cells
series of guidelines used to identify the microorganism that causes
Koch's Postulates a specific disease
Three components of disease
triangle Causal agent, environment, host
Role of each component of All three must be present for disease to occur. Environment must
disease favor causal agent.
triangle Host must favor causal agent.
How humans impact each
component of Manipulate the environment, host-plant resistance,
disease triangle preventative/suppressive/erradicative pesticides
Impact of epidemic when one Slows epidemic to a halt. Disease spread needs all three
component components interacting
of disease triangle does not
, come into
contact with the other two
components
