Lecture I - Introduction & History of Plant Pathology

1. FUNDAMENTALS OF PLANT
PATHOLOGY
Prepared by
Abdinasir Mohamed Ibrahim
M.Sc. (Agri.) Plant Pathology

2. Lecture I
INTRODUCTION & HISTORY OF PLANT
PATHOLOGY

3. Learning objectives
In this presentation you will learn to:
 The word pathology
 Objectives of plant pathology
 Significant of plant diseases
 History of plant pathology

4. Introduction
Plant pathology is the study of the plant diseases and disorders of plants. Plant diseases and
disorders make the plant to suffer, either kill or reduce their ability to survive or reproduce.

5. Term
The term ‘Pathology’ is derived from two Greek words ‘pathos’ and ‘logos’, ‘pathos’ means
suffering and ‘logos’ means to study.
Therefore pathology means “study of suffering”. Thus plant pathology or phytopathology (Gr.
Phyton = plant) is a branch of biology that deals with the study of suffering plants.

6. Objectives
Plant pathology has four major objectives
I. To study diseases/disorders caused by biotic and abiotic agents
II. To study mechanism of disease development
III. To study the interaction between plant and the pathogen in relation to overall
environment
IV. To develop suitable management strategy to surmount the diseases and to reduce the
loss

7. Significant of plant diseases
Fossil evidence indicates that plants were affected by disease 250 million years ago. The plant
disease have been associated with many important events in the history of mankind on the earth.
Wheat smut has been recorded as early as 1900 BC which reduced the yields of the grains used for
making bread.

8. Holy fire or St. Anthony’s fire
After the decline of the Roman Empire, poor people
relied on rye bread as their primary food source.
People who ate the bread made from rye flour
inadvertently ground with ergot suffered from
gangrene due to severe constriction in blood vessel.
Hands and feet literally fall of producing a disease
namely ‘Holy fire or St. Antony’s fire’.
St. Antony’s fire
Ergot
Gangrene feet

9. Late blight of potato
A series of wet and cool condition in the 1840’s led to the outbreak of
disease epidemic called ‘late blight of potato’ which completely
destroyed crop and caused severe potato losses in Northern Europe;
that resulted in the death of hundreds of thousands of people and
emigration of more than one and half million people from Ireland to
the United States. This disease outbreak caused the great ‘Irish
famine’ during 1845 and 1846.
Irish farmers
Effect of Late blight of potato

10. Sri Lanka (Ceylon)
Sri Lanka used to produce maximum coffee in
the world. In 1867 coffee rust attacked the
plantations in Sri Lanka and by 1893 the
export of coffee from Sri Lanka had declined
by 93 percent.
Monoculture - coffee
Coffee seeds

11. Cassava Mosaic disease
Cassava Mosaic disease often results in 15 to 24%
storage root yield losses storage root yield losses of
cassava annually across Sub-Saharan Africa, which is
equivalent to an annual loss of US 1.2 to 2.3 billion and
this led to starvation death of nearly 3,000 people in
Uganda during 1994.
Storage effect
In the field

12. History of Plant Pathology
Ancient Era
The ancient Romans created rust god ‘Robigus’, goddess ‘Robigo’ and
sacrificed red colored animals such as dogs, foxes, and cows during the
festival called Robigalia.
People in those days thought that disease were produced
spontaneously and and believed in theory of spontaneous generation.
Robigalia festival

13. First microscope
1675 Dutch worker Anto Van Leeuwenhoek
developed the first microscope. In 1683 he
described bacteria seen with this microscope.
Leeuwenhoek First microscope

14. Reproductive part of fungus
In 1729 Antonio Micheli (Italian) was the first scientist who
studied fungi and saw their spores under the microscope. He
also proved that if these spores are placed on a piece of fruit
they grow into a new thallus of the fungus.
Micheli

15. Wheat Smut
1755 Mathieu Tillet (French) working with smutted wheat, showed that he
could increase the number of wheat plants developing covered smut by
dusting wheat kernels before planting with smut dust, i.e., with smut
spores. He also noted that he could reduce the number of smutted wheat
plants produced by treating the smut treated kernels with copper sulfate.
He concluded that wheat smut is an infectious plant disease, he believed
that it was a poisonous substance contained in the smut dust
Tillet

16. Microorganism
In 1807 Pierre Prevost (French) observed smut
spores from untreated and treated wheat seed
under the microscope and noticed that those
from untreated seed germinated and grew
whereas those from treated seed failed to
germinate. He proved that disease are caused by
microorganisms.
Prevost Teliospore

17. Phytophthora infestans
In 1853 Anton De Bary (Germany) confirmed the
finding of Prevost. In 1861 he experimentally
proved that the fungus Phytophthora infestans
was the cause of late blight of potato.
Anton De Bary Late blight of potato

18. Germ Theory
In 1861 Louis Pasteur (French) proved that
microorganisms were produced from pre-
existing microorganisms and that most infectious
diseases were caused by germs.
He proved that food spoiled because of
contamination by invisible bacteria, not because
of spontaneous generation
Louis Pasteur Food spoiled

19. Artificial nutrient
In 1887 Richard Petri (Germany), who developed
artificial nutrient media for culturing the
microorganisms (Petri dishes)
Richard Petri Petri dishes

20. Certain microorganism
In 1887 Robert Koch (Germany), who established that for proving
that a certain microorganism was the cause of a particular
infectious disease, certain necessary steps (Koch’s postulates) must
be carried out and certain conditions must be satisfied.
Robert Koch

21. Questions
What are the contributions of
a) Leeuwenhoek
b) Micheli
c) Tillet
d) Prevost
e) De Bary
f) Louis Pasteur