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