Major crop epidemics have caused widespread devastation and significant socio-economic impacts. The Irish potato famine of 1845-49 caused by Phytophthora infestans led to 1 million deaths in Ireland and the emigration of another 1 million people, cutting Ireland's population in half. Coffee rust devastated Sri Lanka's coffee industry in the 1870s, forcing many plantations to collapse or convert to tea. Downy mildew of grapes destroyed Europe's vineyards in the late 1800s, reducing French wine production by 70% in 1915. The chestnut blight introduced in 1904 killed an estimated 4 billion American chestnut trees over 50 years.

1. Topic :- Major crop epidemics and their social impacts
Presented by
Dharmendra kr.
B.Sc. Agriculture hon.
8th sem.
Submitted to :-
Mr. Mithilesh Kumar Pandey
(A.P)

2. contents
1. Introduction
2. List of major epidemics
3. Epidemics and their socio-economic impacts.
4. Conclusions

3. Introduction
Plant disease epidemics continue to impact a world increasingly concerned with the quantity and quality of food
supply.It affects the socio-economic conditions of people.
Epidemics in major food crops causes starvation and food crisis among human as well as in animals due to these
many problems like malnutrition and death occurs.
What is epidemics?
When a pathogen spreads to and affects many individual;Within a certain area and
within a relatively short time, this type of phenomenon is called an epidemic.

4. Major epidemics
Year Disease Locality
1845 Late blight of potato
(Phytophthora infestans)
Ireland
1870 Coffee rust (Hemileia vastatrix) Sri Lanka
1878 Downy mildew of grapevine
(Plasmopara viticola)
France
1900 Lethal yellow of cocoa
(MLO)
Cuba
1904 Chestnut Blight (Endothea
parasitica)
America
1916 Wheat rust (Puccinia tritici) Canada
1921 Bunchy top of Banana (MLO) Australia

5. Cont….
Year Disease Locality
1930 Sigatoka disease of banana
(Mycosphaerella musicola)
America
1936 Red rot of sugarcane
(Colletotrichum falcatum)
UP India
1943 Brown spot of rice
(Helminthosporium oryzae)
Bengal India
1951 Bacterial bought
(Xanthomonas campestris)
Maharashtra India
1969 Souther corn blight
(Helminthosporium maydis)
USA
1984 Apple scab (Venturia
inaequalis)
J&k

6. Cont….
Year Disease Locality
1999 Rice tungro (Tungro virus) Punjab India

7. Epidemics and their socio-economic impacts.
Cause
Late blight of potato
(C.o :- Phytophthora infestans)
Known as Great Famine of 1845-49
Irish Famine 1845
When potato blight made its appearance in Ireland in the second half of 1845, it caused a partial failure of the potato
crop on which so many Irish people were dependent. When the blight returned in 1846 with much more severe effects
on the potato crop, this created an unparalleled food crisis that lasted four years and drove Ireland into a nightmare of
hunger and disease. It decimated Ireland's population, which stood at about 8.5 million on the eve of the Famine.
It is estimated that the Famine caused about 1 million deaths between 1845 and 1851 either from starvation or hunger-
related disease. A further 1 million Irish people emigrated. This meant that Ireland lost a quarter of its population
during those terrible years. The Famine’s impact was most severe in the west of Ireland where some counties lost
more than 50 per cent of their population.

8. Cont…
● Decimated Ireland's population, which stood at about 8.5 million on the eve of the Famine.
● 6 million people left between 1841 and 1900. This figure exceeded the total population of
Ireland at the beginning of the 19th century. By 1901, Ireland's population had been cut
in half, to just 4.4 million. Indeed, the population of the island, although it has been on
the rise since the early 1960s, is still short of 7 million.

9. Cont….
Coffee rust 1870
Co:- (Hemileia vastatrix)
Locality :- Sri Lanka
● The history of the disease serves as an important backdrop to the current crisis. It was first reported in Sri Lanka
(then Ceylon) in 1868 and, within 5 years, had spread across the entire island (Monaco 1977). It became so
devastating in Sri Lanka, southern India, and Java that coffee agriculture had to be effectively abandoned.
● Sri Lanka (Ceylon) for example. used to be a major world coffee producer.however in the mid-1800, rust
devastated coffee growing and the country switched to mainly tea production.
● Large proportion of the country’s coffee plantations were wiped out and against such a backdrop, coffee
cultivation was reduced to a mere 11,392 hectares through the 1900s.

10. Cont..
● Many coffee estates in Sri Lanka were forced to collapse or convert their crops to alternatives not affected by
CLR, such as tea.
● The planters nicknamed the disease "Devastating Emily" and it affected Asian coffee production for over
twenty years.
● By 1890 the coffee industry in Sri Lanka was nearly destroyed, although coffee estates still exist in some
areas.

11. Cont..
Downy mildew of grapevine
C.o. :-(Plasmopara viticola)
Locality:- France (1878)
● By 1882, the disease is already widespread throughout France. It’s the third in a row of grapevine
diseases that destroy Europe’s vineyards. In fact, downy mildew is one of the most economically
significant grapevine diseases for decades to come, producing many record low-yielding vintages up
until 1969.
● In 1915, 70% of the French grapevine production was destroyed by this pathogen. In 1930, 20 million
liters of wine were lost in France (Cadoret, 1931).

12. Cont….
Chestnut Blight
C.o :-(Endothea parasitica)
Locality:- America (1904)
● The chestnut blight was accidentally introduced to North America around 1904 when
Cryphonectria parasitica was introduced into the United States from East Asia from the
introduction of the cultivation of Japanese chestnut trees into the United States for
commercial purposes.
● In the Audubon Guide to North American Trees, the American chestnut has 3 descriptions.
The first is a memory of this tree’s historical stature, which was once so common and useful
that it would make both cribs and caskets. The second, more practical, entry describes how
these trees look to the modern observer: small and enfeebled by the unrelenting chestnut
blight fungus that prevents these trees from reaching their full potential. The third entry
describes the etiology of chestnut blight, which killed an estimated 4 billion American
chestnuts in the 50 years following its introduction to New York in the early 1900’s.

13. Cont….
Red rot of sugarcane
Co.:- (Colletotrichum falcatum)
Locality:- UP India (1936)
● Red rot of sugarcane was first reported from Java (now Indonesia) by Went in 1893. During 1895-
1900 the disase assumed epidemic proportion in the Godavari Delata of Andhra Pradesh, India
(Barber 1901) Butler (1906) published a detailed account of this disease from PUSA, Bihar and
gave it the name 'Red rot.

14. Cont…
● During the 1938-1939 season, a red rot epiphytotics of exceptional severity occurred in the
subtropical region predominantly in Uttar Pradesh (UP) and Bihar, the major sugarcane region in
India.
● This devastation resulted in failure of the major commercial variety Co 213, in which thousands of
hectares were devastated. Due to the poor supply of canes, the sugar mills in the eastern UP
crushed only one-third of their normal canes during 1938-1939 and half during 1939-1940 .
● Severe infections of red rot can cause loss of nearly two-third of cane stalks produced in subtropical
India

15. Cont..
Brown spot of rice
(Helminthosporium oryzae)
Locality:- Bengal India (1943)
● The Bengal famine of 1943 was one of the most devastating famines in history that hit the Bengal province
in British India at the time of the Second World War. It was a major famine that claimed lives of around
2.1–3 million people. The deaths were predominantly caused due to starvation and diseases like malaria
and cholera that got worsened because of population displacement, malnutrition, poor sanitation and
paucity of health care. Historians often tag the famine as “man-made” pressing that it was created and
intensified by wartime colonial policies.
● on January 9, 1943 resulting in flooding the rice fields with salt water. It claimed thousands of lives and
witnessed an outbreak of the Helminthosporium oryzae fungus that badly affected the remaining rice plants

17. Conclusions
Each and every epidemics were the most destructive and change the life of people. It change
the agricultural practices and depencey on single kind of food.It affect the population very
badli, people lost their life due to starvation and related disease. people start to migrate other
places and leave their land and house . These epidemics teach some lessons like
diversification of agriculture and no dependency on single food material.