Plant Pathology: Disease Cycles and Hosts

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Questions and Answers

What type of disease is caused by pathogens that can complete multiple life cycles within one crop season of the host plant?

Monocyclic disease

Polycyclic disease (correct)

Deficiency disease

Disorder

What is the term for a plant that is not related to the main host of a parasitic fungus, where it produces its different stages to complete one cycle?

Symbiotic host

Mutualistic host

Main host

Alternate host (correct)

What is the term for the effect of one or more environmental factors that makes a plant vulnerable to attack by a pathogen?

Antagonism

Predisposition (correct)

Mutualism

Symbiosis

What is the term for a mutually beneficial association of two or more different kinds of organisms?

Symbiosis Signup and view all the answers

What is the term for an abrupt appearance of a new characteristic in an individual as a result of an accidental change in genes present in chromosomes?

Mutation Signup and view all the answers

What is the term for any reduction in the quality or quantity of yield or loss of revenue resulting from crop injury?

Cop Damage Signup and view all the answers

What is the term for the organism that grows on a non-living substrate within a living plant?

Saprophyte Signup and view all the answers

What is the ability of a pathogen or parasite to cause disease known as?

Pathogenicity Signup and view all the answers

What is the term for the sequence of events that occur during disease development?

Pathogenesis Signup and view all the answers

Who forwarded the four essential procedural steps for correct diagnosis of a disease?

Robert Koch Signup and view all the answers

What is the process by which a pathogen enters a host plant?

Inoculation Signup and view all the answers

What is the term for a parasite that is able to survive and reproduce in the absence of its host?

Facultative saprophyte Signup and view all the answers

What is the primary goal of the isolation step in identifying the causal organism of a disease?

To isolate the pathogen in pure culture Signup and view all the answers

What is the purpose of the re-isolation step in Koch's postulates?

To verify the cultural characteristics of the pathogen Signup and view all the answers

What type of changes occur in the host plant during pathogenesis?

Both morphological and physiological changes Signup and view all the answers

What is the effect of the pathogen on the host plant's growth?

It inhibits the growth of the host plant due to growth regulators Signup and view all the answers

What is the significance of the inoculation step in Koch's postulates?

It helps to verify the pathogen's ability to cause disease Signup and view all the answers

Who added the re-isolation step to Koch's postulates?

E.F. Smith Signup and view all the answers

What is the effect of abnormality in respiration on host tissues?

Disturbed permeability of cell membrane Signup and view all the answers

Why is 'management' of a disease more practical than 'control'?

Because management is a continuous process Signup and view all the answers

How many basic concepts or principles of plant disease management are there?

Six Signup and view all the answers

What is the objective of avoidance of the pathogen?

To plant a crop at times when inoculum is inactive Signup and view all the answers

What is required to prevent the spread of a disease?

Legislative measures Signup and view all the answers

What is impacted by the effect on the process of translation and transcription?

Protein synthesis Signup and view all the answers

What is the main objective of eradicating a pathogen?

To eliminate or destroy inoculum at the source Signup and view all the answers

What is the purpose of treating seed and planting materials?

To exclude inoculum of the pathogen Signup and view all the answers

What is the role of quarantine regulations in plant disease management?

To exclude inoculum of the pathogen Signup and view all the answers

What is the purpose of crop rotation in plant disease management?

To avoid the pathogen Signup and view all the answers

What is the purpose of sanitation of the field in plant disease management?

To eradicate the pathogen from the source Signup and view all the answers

What is the purpose of biological control of plant pathogens?

To eradicate the pathogen from the source Signup and view all the answers

Study Notes

Pathogen Types and Host Plant Interaction

Diseases caused by pathogens that can complete multiple life cycles within one crop season are referred to as polycyclic diseases.
A secondary host is a plant unrelated to the main host of a parasitic fungus, allowing the pathogen to complete different stages of its life cycle.

Vulnerability and Disease Development

The term pathogen susceptibility refers to the influence of environmental factors that render a plant vulnerable to pathogen attacks.
A symbiotic relationship describes a mutually beneficial association between two or more different organisms.

Genetic and Yield Implications

An abrupt genetic mutation occurs when a new characteristic appears in an individual due to an accidental change in its genes.
Yield loss is defined as any reduction in the quality or quantity of crop yield due to injury or disease.

Pathogen Growth and Disease Mechanisms

A saprophyte is an organism that thrives on a non-living substrate within a living plant.
The pathogenicity of a pathogen refers to its ability to cause disease.

Disease Development and Diagnosis

The disease development sequence encompasses the steps a pathogen takes to establish infection and cause disease.
Koch's postulates were forwarded by Robert Koch, and they outline essential procedural steps for diagnosing a disease accurately.

Pathogen Entry and Survival Strategies

The infection process describes how a pathogen enters a host plant.
A facultative parasite can survive and reproduce in the absence of its primary host.

Diagnostic Steps and Plant Response

The primary goal of the isolation step in diagnosis is to identify the causal organism of a disease from the host.
The re-isolation step in Koch's postulates serves to confirm that the pathogen isolated from the diseased plant can cause disease in a healthy plant.

Host Plant Changes and Growth Effects

During pathogenesis, notable physiological changes occur in the host plant as it responds to the pathogen.
Pathogens generally hinder a host plant's growth, affecting its health and productivity.

Significance of Inoculation

The inoculation step in Koch's postulates is crucial for establishing a link between the pathogen and the disease symptoms caused in healthy plants.

Management and Control Concepts

Management of diseases is often more feasible than mere control, as it encompasses holistic strategies to minimize disease occurrence.
There are generally three basic concepts of plant disease management to effectively reduce disease impact.

Objectives and Prevention Strategies

The goal of avoiding pathogens is to prevent disease by minimizing exposure and infection risks.
Preventing disease spread requires implementing measures such as crop rotation, sanitation, and treating planting materials.

Translation, Eradication, and Quarantine

Pathogen effects can disrupt the processes of translation and transcription, ultimately impacting plant health.
The main objective of eradicating a pathogen is to eliminate its presence entirely to safeguard plant health.
Treating seeds and planting materials is essential to ensure they are free from pathogens before sowing.

Roles of Management Techniques

Quarantine regulations implement measures to restrict the movement of potentially infected materials, protecting crop health.
Crop rotation disrupts pathogen life cycles by alternating different crops, reducing recurrence of specific diseases.
Sanitation in the field ensures removal of infected debris to minimize pathogen survival and spread.
Biological control of plant pathogens involves utilizing natural enemies or competitors to manage pathogen populations sustainably.

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Description

Test your knowledge of plant diseases caused by pathogens, including multiple cycle diseases and heteroecious fungi. Learn about alternate hosts and environmental factors that contribute to disease predisposition.