plant pathology

1. INTRODUCTION TO PLANT PATHOLOGY

2. Plant Pathology (Phytopathology): is a
Greek Word which is made by three words:
Phyton + Pathos + logos
Plant + suffering/ailments + study/knowledge
Definition:
“Plant Pathology is that branch of agricultural, botanical
or biological science which deals with the study of the
causes, etiology, resulting losses and management/ control
of plant diseases.”

3. OBJECTIVES OF PLANT PATHOLOGY
To study the biotic, abiotic and environmental causes
of plant diseases.
To study the mechanism of disease development.
To study the interaction between plant and pathogen.
To develop the methods of plant disease
management/control.

4. HISTORICAL DEVELOPMENT
OF PLANT PATHOLOGY
► Theophrustus (370-286 BC) – He write a
book entitled “Inquiry into Plants” . He
wrote the observations regarding diseases
in this book.
Following are books where description of plant disease
has been given.
► Rigveda (3700 BC)
► Atharveda (1500-500 BC)
► Arthsasthra (321-186 BC)

5. ■
Shushrata Sanhita (200-500 AD)
■
Vishnu Puran(500 AD)
■
Agni Puran (500-700 AD)
■
Vrksayurveda (800 AD) by Surpala
■
Shakaspeare, Kalidas (Raguvans)
■
Bible,Boudh Literature
■
Barahat Sanhita-Varahamihar

6. Development of Plant Pathology
■
■
Leeuwenhock (1665) – He invent Microscope
Micheli (1725)- Seen spore first time. He is called
“Father of Mycology”
■ Tillet (1755) – Worked on Smut and Bunts of Wheat
■ Prevost (1755-1819) -
is
He proved that bunt of Wheat
caused by a fungus
■ Needham(1743) – Worked on Ear Cokel Disease of
Wheat
■ Anton de Bary (1831-1888) – Worked on Late Blight of
Potato
“Father of Modern Plant Pathology”

7. ■ Julius Kuhn (1858) – Write first book of Plant Pathology entitled
“Disease of Cultivated Crops Their Causes And Their Control”
■ T. J. Burril (1878) – Reported first plant disease caused by bacteria
entitled ‘Fire Blight of Peach and Apple ‘
■ Prof. Millaradet (1885) – Prepare first time “Bordeaux Mixture”
■ Mayer (1886) – Worked on Tobacco Mosaic caused by Virus
■ Doi et. al. (1967) – First time reported that Yellows Disease is caused by
Mycoplasma
■
■
Diener (1971) – Reported first time that Potato Spindle Tuber disease is
caused by Viroid
Davis et. al. (1972) – Reported first time Corn Smut is caused by
Spiroplasma.

8. PLANT PATHOLOGIST OF INDIA
● E. J. Butler (1901-1920) – First plant pathologist in
India. He wrote a book -“Fungi and disease in plant”.
He is known -“Father of Plant Pathology in India”
● D. D. Conninghum & A. Barclay – Start study and
identification of fungi.
● J. F. Dastur (1886-1971)- First Indian Plant Pathologist.
He worked on Caster and Potato diseases caused by
Phytophthora.

9. ●B. B. Mundkar
development of
(1948)– He worked on
disease resistant varieties
against wilt of cotton and identification and
classification of Indian smut fungi. Established
Indian Phytopathological Society in New Delhi.
● K. C. Meheta – Worked on Rust in India.
● S. P. Raychoudhary- Worked on Viral plant
diseases.
● Y. L. Nene- Reported Khaira Disease of rice.
● R. S. Singh- Wrote a famous book - ‘Plant
Disease’

10. IMPORTANT EVENTS IN PLANT
PATHOLOGY
1845-46 Late Blight of Potato/Irish famine
1867 Coffee Rust in Sri Lanka
1869 Coffee Rust in Southern India
1918-19 Brown Leaf Spot of Rice in Delta of
Krishana & Godawari rivers
1938-39 Red Rot of Sugarcane
1943 Brown leaf spot of rice/Bengal famine
1956-57 Rusts in Bihar

11. IMPRTANCE OF PLANT DISEASE
Losses caused by different pest in crops
PEST
Weed
Diseases
Insects
Storage pests
Rodents
Others
Total
LOSS (%)
33
26
20
7
6
8
100

12. • Qualitative importance
• Quantative importance
• Aesthetic value
• Farmers have to change the crop rotation
• Expenditure on protection
• Harmful for human being
• Employment
• International trade
• Agricultural industries
• Others
Total Loss by Diseases =10-12%

13. PLANT DISEASE
According to American Phytopathological Society
and British Mycological Society:
“Disease is a malfunctioning
process which is caused by
irritation in
some continuous
which result some suffering
producing symptoms”

14. Causes of Plant Diseases
Earlier Concepts regarding cause of Plant diseases:
• Yahudhi – regarded that disease is due to Ishwar
ka Karodh (Anger of God).
• Unani – worship of Suryanarayan for protecting
their crops from diseases.
• Rome – residents of Rome worship of Robigo and
Robigus (Rust God and Goddess respectively) for
protecting their crops from rust.

15. PATHOGEN
“Any entity which can insite the disease is
known as pathogen”
Classification of Plant Pathogen
(A) Biotic pathogens or Animate Causes
1. Fungi
2. Bacteria
3. Phytoplasma/Spiroplasma
4. Nematode
5. Algae
6. Protozoa
7. Parasitic Plants

16. (B). Mesobiotic causes
1. Virus
2. Virod
3. Virusoids
4. Prion

17. (C). Abiotic or Inanimate causes
1. Adverse climatic conditions
(a). Light (b). Tem. (c). Humidity
(d). Rain (e). Hail (f). Frost
(g). Strom (h). R. .H
2. Adverse soil conditions
(a). Soil moisture
(c). Structure
(e). Nutrition
(b). Texture
(d). Aeration
(f). Soil pH

18. 3. Chemical Injuries
(a). Pollution (b). Pesticides
4. Improper Cultural Practices
(a) Depth of sowing
(b) Improper irrigation
(c) Improper fertilization
(d) Improper harvesting

19. Survival of Pathogen
1. Soil
2. Seed
3. Plant debris/ crop residues
4. Plants itself
4. Collateral Host
5. Alternate Host

20. Dissemination or Dispersal of
Pathogen
(A) Autonomous Dissemination
(1) By Soil
(2) By Seeds
(3) By Plant and Plant Parts

21. (B). Passive Dissemination
(1) By Air
(2) By Water
(3) By Vectors
(4) By Humans

22. KOCH’S POSTULATES
1. Association
2. Isolation
3. Inoculation
4. Reisolation

23. Disease Scenario
Total Plant Diseases in the world - 80,000
In India - 5,000 diseases
Average disease per plant - 100

24. Classification of Plant Disease
1. According to affect on the host plant
(i) Localized diseases- Exp.- Rust of Wheat
(ii) Systemic Diseases-Exp.- Loose Smut of Wheat
2. According to symptoms & sign
(i) Smut (ii). Rust (iii). Mildew (iv). Wilt
(v). Blight (vi). Canker (vii). Root rot

25. 3. According to parts of the plant affected
(i) Root diseases: Affect root of plants. Exp. Root rot of
vegetables
(ii) Stem diseases: Affect stem of plants. Exp. Stem gall of
coriander.
(iii) Foliar disease: Affect foliar parts of plants. Exp. Leaf
spot of Sorghum.
(iv) Fruit diseases: Affect fruit of plants. Exp. Fruit rot of
Brinjal

26. 4. According to host plant affected
(i) Field crop diseases
(ii) Vegetables diseases
(iii) Fruit tree diseases
(iv) Forest diseases
(v) Forage crop diseases

27. 5. According to mode of perpetuation and spread
(i) Seed-borne diseases: Exp.- Loose smut of wheat
(ii) Soil-borne diseases: Exp.- Sheath blight of rice
(iii) Air-borne diseases: Exp.- Rust of wheat

28. 6. According to mode of multiplication of
the pathogen
(i) Simple interest/monocyclic diseases: Only
one cycle of pathogen complete in one season.
Exp. - Loose Smut of Wheat
(ii) Compound interest/polycyclic diseases:
Several cycles of pathogen complete in one
season.
Exp. - Black Rust of Wheat

29. 7. According to major casual
agents
(A) Infectious diseases
(i) Fungal diseases
(ii) Bacterial diseases
(iii) Viral diseases
(iv) Nematode disease
(v) Algae disease

30. (B). Non infectious diseases
(i) Diseases caused by tem.
(ii) Diseases caused by air pollution
(iii) Diseases caused by mineral toxicity
(iv) Diseases caused by toxicity of
pesticides
(v) Diseases caused by nutritional deficiency
(vi) Diseases caused by acidity/alkalinity

31. 8. According to occurrence
(i) Endemic disease
(a) These disease appear in a ‘Limited area’
(b) Diseases appear ‘Every Year’
(c) These do no cause ‘More Loss’
Exp. Early blight of potato

32. (ii). Epidemic or epiphytotic diseases
(a) These disease appear in a ‘Large Area’
(b) Diseases appear ‘Periodically’
(c) These diseases cause ‘More Loss’
Exp. Late blight of potato

33. (iii). Sporadic diseases
(i). These diseases are ‘Sporadic’
(ii) Appear on ‘Irregular Intervals’
(iii) These diseases cause ‘Less loss than
epidemic diseases’
Exp. Powdery mildew of mango

34. (iv). Pandemic diseases
(i) These diseases appear in ‘Whole
world/ continent/ sub continent’
(ii) Appear at ‘Periodic Intervals’
(iii). These cause ‘Heavy Loss’
Exp. Late blight of potato

35. Thankyou all
A.Swaroopa Rani