TOPIC 1 24-Oct-2021 Perjumpaan Bersemuka PJJ Minggu Pertama

PLP3204
Fundamental of Plant
Pathology
by
Dr. Siti Izera Ismail
Department of Plant Protection, Block E
Faculty of Agriculture
izera@upm.edu.my
CLASS SCHEDULE PROGRAM BACELOR SAINS PERTANIAN PJJ
SEMESTER 1 2021/2022
Week Date Lecture Topic
Perjumpaan bersemuka pertama

1 24/10/2021 1
20/11/2021 Amali
2 Amali 1
(Sabtu)
28/11/2021
Amali Amali 2
(Ahad)
18-19 Disember Mid-term Peperiksaan pertengahan (30%)
3
exam
8-9/01/2022
2 Perjumpaan bersemuka kedua
4 (15/16/01/2022

5/02/2022
5 Amali Amali 3
(Sabtu)
12-13 Feb 2022 Final Peperiksaan akhir (40%)
COURSE ASSESSMENT
Course work:
Peperiksaan Pertengahan 30%
Assignment/Term paper 15%
Laboratory report 15%
Final exam:
Theory 40%
Total 100%
REFERENCES
1. Agrios, GN. 2005. Plant Pathology (5th Edition). Academic Press Inc., USA. 922 pp.
2. Hull, R. 2002. Matthews’ Plant Virology (4th Edition). Academic Press Inc., London. 1001 pp.
3. Blakeman, JP. 1994. Ecology of Plant Pathogens. CAB International, London. 384 pp.
4. Masao Goto. 1992. Fundamentals of Bacterial Plant Pathology. Academic Press Inc., USA.
5. Walkey, DGA. 1991. Applied Plant Virology (2nd Edition). Chapman and Hall, USA, 338 pp.
6. Luc, M, Sikora, RA and Bridge, J. 1990. Plant Parasitic Nematodes in Subtropical and Tropical
Agriculture. CAB International, London, 629 pp.
Components of the class
n  Lectures
n  Practical class
n  Term paper
-  In-class presentation of plant disease
diagnoses by students
-  Assignment
Objectives :
n  Gain a better understanding of etiology,

ecology and management of plant
diseases in Malaysia
n  Develop or enhance expertise in plant
disease diagnosis
Plant Pathology:
Introduction, History,
Pathogenicity
Learning Outcome (LO)
n  To explain the principles of plant
pathology and plant disease
n  To recognise and describe disease

symptoms and perform pathogenicity
studies (A1, C2, P1, EM1)
Plant diseases
§  Reduce the quality and quantity of plant
products
§  Can cause significant financial losses

through reduced yields or aesthetic
qualities and the cost of control
practices
Plant disease
n  Any malfunctioning of host cells and

tissues that results from continuous
irritation by a pathogenic agent or
environmental factor and leads to
development of symptoms.
What is wrong with my plant?
Citrus scab
What is wrong with my plant?
blotch
necrotic area of tissue irregular in form
(leaf blotch of grape caused by Briosia ampelophaga)
borer
insect or insect larva that forms tunnels or cavities in the bark or
within the wood of trees
(rhododendron borer larvae, Synanthedon rhododendri)
What is the difference between
'symptoms' and 'signs’?
Our diagnosis of plant diseases is based
on examination of symptoms and signs
n  Symptom – alteration in the

appearance of a plant resulting from
disease or injury
n  Sign – pathogen structure or product
seen on or in an infected plant
Koch's postulates are used to:
A.  demonstrate spontaneous generation

B.  demonstrate that viruses are filterable
agents
C. demonstrate the use of solid media to
obtain pure cultures
D. demonstrate a cause-effect relationship
between an infectious agent and a disease
E. demonstrate sterility
Plant Pathology
n  A science that studies plant diseases and their
causes.
n  Includes elements of causal agents, mechanisms of
infection and control methods.
n  Challenges faced:
n  To reduce food losses
n  Improving food quality
n  Safeguarding environment
Plant Pathology (cont’)
n  The concept of disease:

n  Disease: Series of invisible and visible responses
of plant cells to a pathogenic organism or
environmental factor that result in adverse
changes in the plant.
n  Adverse changes: Detrimental disturbance in
the physiological functions of the plant.
n  Disease = disturbance from plant pathogen
or environmental factor that interferes with
plant physiology
•  Causes changes in plant appearance or

yield loss
•  Disease results from:
Ø Direct damage to cells
Ø Toxins, growth regulators or other
byproducts that affect metabolism
Ø Use of nutrients and water or interference
with their uptake
Plant Diseases
2 categories:
1.  Infectious (biotic) diseases
2.  Non-infectious (abiotic) diseases
Plant Diseases (cont’)
1.  Infectious (biotic) diseases

n  Caused by biotic factors: e.g., parasitic higher
plants & pathogens
n  Pathogens: microorganisms that cause disease
in plants
n  Various groups of pathogen:
n  Protozoa
n  Fungi & fungal-like organisms
n  Prokaryotes (bacteria & mollicutes)
n  Viruses & viroids
n  Nematodes
Source: Agrios, 2005

Dissemination of plant pathogens
Student activity: Revision
v  What is plant pathology?
v  What is plant disease? Remember the
disease triangle.
2.  Non-infectious (abiotic) diseases
n  Caused by abiotic factors: e.g., unfavorable
environmental conditions
n  Examples:
n  lack or excess of soil moisture
n  lack of oxygen
n  too low or too high a temperature
n  air pollution
n  nutrient deficiencies, etc.
History of Plant Pathology
n  370-286 B.C. – Theophrastus: a Greek philosopher
wrote about plant diseases.
n  Robigus, the Roman god, was believed to protect
cereal crops from the destruction of rusts.
n  1675 – Leeuwenhoek, a Dutch scientist, began
using microscope to examine plants and
microorganisms.
n  1729 – Micheli, an Italian botanist, examined fungi
and their reproductive structures.
History of Plant Pathology (cont’)
n  1840 – Epidemic of potato late blight disease in
Europe.
n  1861 – Anton de Bary, a German botanist (Father
of Plant Pathology) demonstrated that Phytophthora
infestans was the causal agent of potato late blight
disease.
Anton de Bary

History of Plant Pathology (cont’)
n  1878 – First fungicide used (Bordeaux mixture).

n  1965 – First systemic fungicide used.
n  1967 – Mollicutes was demonstrated to be a plant
pathogen.
n  1992 – Resistance gene against plant diseases was
identified.
Losses Caused By Plant Diseases
n  Millions of people depend on plants & plant
products for survival.
n  Plant diseases could cause:
n  Starvation & death (e.g., Irish famine)
n  Economic losses to growers
n  Increased prices of products to consumers
n  Direct & severe pathological effects on humans & animals
that eat diseased plant products
n  Destroy the beauty of environment (damaging plants)
n  Pollution to water and environment (chemical control)
Losses Caused By Plant Diseases:
Specific Examples
1.  1840 - Epidemic of

potato late blight
disease caused famine
in Ireland
•  1 million deaths
•  1 ½ millions migrated
to North America

Potato late blight, Phytophthora infestans (oomycete)
caused 1846-1848 Irish potato
famine
Specific Examples (cont’)
2.  1870 - Epidemic of

coffee rust in Ceylon
(Sri Lanka)
•  Destruction of coffee
plantations
•  Converted into tea
plantations

Coffee rust, Hemileia vastatrix (fungus)
why you drink shade-grown coffee

Specific Examples (cont’)
3.  Epidemic of South

American Leaf Blight
(SALB) disease in
Brazil
n  Destroyed rubber
industry
n  Microcyclus ulei
Source: JPT, UPM

Rice blast, Magnaporthe oryzae (fungus)
Controlled by resistance breeding

Citrus variegated chlorosis, Xylella fastidiosa (bacterium)
Soybean rust, Phakopsora pachyrhizi (fungus)
- alarming exotic plant pathogen, came north from Brazil; but it has not caused
big losses
Disease Symptoms and
Pathogenicity Test
Disease Symptoms
Divided into 3 main categories:
1.  Necrosis
a)  Local
b)  General
2.  Overgrowth
a)  Hypertrophy
c)  Hyperplasia
3.  Hypoplasia
Disease Symptoms (Cont’)
1.  Necrosis
n  Death of cells or tissues
Local necrosis General necrosis
Leaf spot Anthracnose Wilt
Downy mildew Stem canker Dieback
Source: JPT, UPM

a) Local necrosis
•  limited to cells
surrounding the invading
pathogen
e.g.: leaf spot, anthracnose,

rust, downy mildew,
powdery mildew, canker
Stem canker
b) General necrosis
more general
e.g.: damping-off, blight, blast, dieback, wilt
Damping off
Damping off is a disease of seedlings caused by one of several different

fungi that may either be present in the soil or seed-borne.
•  Overgrowth
n  Hypertrophy n  Hyperplasia
n  Cell enlargement n  Fast cell division
n  e.g.: club root, smut n  e.g.: Witches’ broom
Witches’ broom
Club root Smut
Source: JPT, UPM
Corn smut
3.  Hypoplasia
n  Size of cells reduced
n  Plant growth retarded
n  Color change
(chlorosis)
n  e.g.: mosaic
Mosaic
Source: JPT, UPM


Pathogenicity
•  The capacity of a microbe to
produce disease
•  The capacity of a microbe to cause

damage in a host
What are Koch’s four postulates for
establishing proof of pathogenicity?
Koch's postulates are used to:
A.  demonstrate spontaneous generation

B.  demonstrate that viruses are filterable agents
C. demonstrate the use of solid media to obtain
pure cultures
D. demonstrate a cause-effect relationship
between an infectious agent and a disease
E. demonstrate sterility
Koch’s postulates
n  Demonstrating the pathogenicity of a
microorganism
Robert Koch
(1843-1910)
Koch’s postulates
n  Step 1: Association : the suspected
pathogen must be consistently
associated with the diseased plant
n  Step 2: Isolation: the pathogen must be
isolated and grown in pure culture and
its characteristics described.
Koch’s postulates
n  Step 3: Inoculation, the pathogen from
pure culture is inoculated into a healthy
plant of the same species or variety and
it must produce the same symptoms
and signs.
n  Step 4:Re-isolation, the pathogen is re-
isolated from the inoculated plant and
its characteristics must be the same as
the organism initially isolated in step 2.
Revision
n  What are Koch’s four postulates for
establishing proof of pathogenicity?
Thank You

TOPIC 1 24-Oct-2021 Perjumpaan Bersemuka PJJ Minggu Pertama

Uploaded by

Copyright:

Available Formats

TOPIC 1 24-Oct-2021 Perjumpaan Bersemuka PJJ Minggu Pertama

Uploaded by

Document Information

Original Description:

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

TOPIC 1 24-Oct-2021 Perjumpaan Bersemuka PJJ Minggu Pertama

Uploaded by

Copyright:

Available Formats

PLP3204

Week Date Lecture Topic

Perjumpaan bersemuka pertama

n Gain a better understanding of etiology,

n To recognise and describe disease

§ Can cause significant financial losses

n Any malfunctioning of host cells and

n Symptom – alteration in the

A. demonstrate spontaneous generation

n The concept of disease:

• Causes changes in plant appearance or

1. Infectious (biotic) diseases

Source: Agrios, 2005

Source: Agrios, 2005

n 1878 – First fungicide used (Bordeaux mixture).

1. 1840 - Epidemic of

Source: Agrios, 2005

2. 1870 - Epidemic of

Source: Agrios, 2005

why you drink shade-grown coffee

3. Epidemic of South

Source: JPT, UPM

Controlled by resistance breeding

Leaf spot Anthracnose Wilt

Downy mildew Stem canker Dieback

Source: JPT, UPM

e.g.: leaf spot, anthracnose,

Damping off is a disease of seedlings caused by one of several different

Source: JPT, UPM

Source: Agrios, 2005

• The capacity of a microbe to cause

A. demonstrate spontaneous generation

You might also like

n  Gain a better understanding of etiology,

n  To recognise and describe disease

§  Can cause significant financial losses

n  Any malfunctioning of host cells and

n  Symptom – alteration in the

A.  demonstrate spontaneous generation

n  The concept of disease:

•  Causes changes in plant appearance or

1.  Infectious (biotic) diseases

n  1878 – First fungicide used (Bordeaux mixture).

1.  1840 - Epidemic of

2.  1870 - Epidemic of

3.  Epidemic of South

•  The capacity of a microbe to cause

A.  demonstrate spontaneous generation