Key Terms in Plant Pathology

Aug 26, 2024

Terms and Concepts in Plant Pathology

Overview

  • Objective: Explain different terms and concepts in plant pathology.
  • Importance of examining fruits and vegetables before purchasing to avoid damaged goods.
  • Damage to fruits and vegetables can be due to diseases caused by biotic or abiotic agents.

Key Definitions

  • Plant Disease: Abnormality in a plant's structure/function due to irritation from pathogenic agents or environmental factors.
    • Dis + Ease = Uneasiness.

Types of Diseases

  • Infectious Diseases: Caused by pathogenic organisms (fungi, bacteria, viruses, etc.) that can spread from diseased to healthy plants.
  • Non-infectious Diseases: Caused by abiotic factors (e.g., environmental conditions) but not pathogens.

Disorders

  • Abnormalities in plants due to abiotic factors (e.g., nutrient deficiency, adverse conditions).

Pathogens and Disease Agents

  • Pathogen: Organism causing disease in a host.
  • Causal Agent: Biotic or abiotic factor that incites disease/injury.
  • Causal Organism: A biotic pathogen.
  • Virulent Pathogen: Capable of causing disease.
  • Avirulent Pathogen: Variant that does not cause severe disease.

Pathogenicity and Pathogenesis

  • Pathogenicity: Capability of a pathogen to cause disease.
  • Pathogenesis: Series of events from pathogen contact to symptom appearance.

Host Concepts

  • Host: Plant invaded by a parasite.
    • Resistance: Host's ability to overcome a pathogen.
    • Tolerance: Host's ability to sustain disease effects without significant injury.
    • Susceptibility: Inability to resist pathogen attack.
    • Hypersensitivity: Excessive sensitivity leading to localized cell death.

Signs and Symptoms

  • Signs: Physical evidence of the causal factor (e.g., spores, chemical residues).
  • Symptoms: Visible responses of a plant to factors resulting in abnormalities (e.g., wilting, rot).
  • Syndrome: Totality of effects from one disease in a host.

Infection Terms

  • Inoculum: Pathogen parts causing infection.
  • Propagules: Structures that can propagate the organism.
    • Primary Inoculum: Initiates first infection.
    • Secondary Inoculum: Produced by primary infection.
  • Infection: Establishment of a parasite on or within a host.
    • Primary Infection: First infection of a plant by a pathogen.
    • Secondary Infection: Caused by inoculum from primary infection.

Life Cycle and Disease Cycle

  • Life Cycle of Infectious Disease: Sequence of events between appearance and reappearance of the pathogen.
  • Disease Cycle: Chain of events in disease development.

Disease Transmission

  • Pathogens transmitted by biotic (e.g., insects) and abiotic factors.
  • Vectors: Agents that carry and transmit pathogens.

Conditions for Disease Occurrence

  1. Susceptible Host Plant: Must be at a susceptible developmental stage.
  2. Active Pathogen: Must be in a conducive stage to infect.
  3. Suitable Environment: Conditions must be fitting for disease.

Disease Triangle

  • Represents the interaction of host, pathogen, and environment.
  • Breakage in any leg of the triangle hinders disease occurrence.

Disease Control Strategies

  • Avoidance: Grow plants when pathogens are inactive.
  • Exclusion: Prevent pathogen entry.
  • Eradication: Eliminate established pathogens.
  • Protection: Modify environment or use chemicals to protect plants.

Summary

  • Understanding plant pathology terminologies is essential for effective research and disease control.