This document provides an introduction to plant pathology. It defines plant pathology as the study of plant diseases caused by pathogens and environmental conditions. Plant disease is defined as a malfunctioning process caused by continuous irritation that produces symptoms, impairing the plant's quality and value. Plant diseases are classified as either infectious, caused by living pathogens that can spread, or non-infectious, caused by non-living factors like temperature, moisture, pollution or nutrient issues.

1. MIC 319
FUNDAMENTALS OF
AGRICULTURAL
MICROBIOLOGY
CHAPTER 1
INTRODUCTION TO PLANT
PATHOLOGY
BY
SITI NORAZURA JAMAL
03 006/ 06 483 2132
norazura6775@ns.uitm.edu.my

2. Outline
• Plant pathology definition
• Plant disease definition
• Plant diseases classification

3. PLANT
PATHOLOGY

4. PLANT PATHOLOGY
• Also be referred as “PHYTOPATHOLOGY”.
• A science that study plant disease
• The disease are caused by pathogens
(infectious diseases) and environmental
conditions (physiological factors)
• Improve the chances of plant survival

5. PLANT DISEASE

6. Definition
“ A malfunctioning process that is caused by
continuos irritation and produce symptoms”
(Horsfall & Cowling)
“ A deviation from normal growth or structure of
plants that is sufficiently pronounced and
permanent to produce visible symptoms or to
impair quality and economic value”
(Stakman & Harrar)

7. Definition
Healthy plant
• The ability to carry out
normal physiological
functions at a acceptable
level consistent to genetic
potential
Sick/diseased plant
• A multifunctioning process
that is caused by continuous
irritation and produce
symptoms

8. Healthy plant
• Normal physiological functions include:
 Normal cell division, differentiation &
development
 Absorption of water and minerals from the soil
and translocation
 Photosynthesis and translocation of
photosynthesis
 Utilization and storage of photosynthates
 Reproduction

9. Healthy plant

10. Sick/diseased plant
• A plant would not have all of these at once.
• Plant disease is any disruption (biotic or
abiotic) of the plants normal metabolism.

11. Sick/diseased plant
“ the malfunctioning of host cells and tissues that
results from their continuous irritation by a
pathogenic agent or environmental factor and
leads to the development of symptoms.
“ disease in a condition involving abnormal changes
in the form, physiology, integrity, or behavior of
the plant.’
“ such changes may result in partial impairment or
death of the plant or its parts’
(George N.Agrios)

12. Sick/Diseased plant

13. Healthy plant vs diseased plant

14. Plant diseases
classification

15. Classification of
plant disease
Infectious
Non infectious

16. Infectious disease
• A disease that is caused by a pathogen that
can spread from a diseased to healthy plant
• Disease that is caused by living organism .
• E.g. Pectobacterium atrosepticum (potato
pathogen)

17. Non infectious disease
• Disease that is caused by non living organism
• Could not be spread to other healthy plant
• E.g. factors:
 Too low/high temperature
 Lack/excess of soil moisture
 Air pollution
 Nutrient deficiencies
 Mineral toxicities
 Soil acidity or alkalinity