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
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
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)
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