11. A few examples of devastating
diseases are:
1. Potato Late Blight
2. Ergot of Rye
3. Black Stem Rust of Wheat
4. Southern Corn Leaf Blight
5. Dutch Elm Disease
6. Bacterial Canker on Citrus
7. Plum Pox Virus on Stone Fruit
All of these are infectious diseases
caused by plant pathogens.
12. Let’s take a closer look at
a few of these important
plant diseases
13. Late Blight of Potato
Caused by the fungus Phytophthora infestans
• The fungus killed most of the potatoes
grown in Ireland during the mid 1800’s.
• Potatoes were the main source of food for
the Irish people.
• This plant disease resulted in the Irish
Potato Famine of 1845
1 million people died
1.5 million people left Ireland
15. Ergot of Rye
Caused by the fungus Claviceps purpurea
The pathogen produces a structure
called a sclerotium that grows in place of
the rye kernel. This sclerotium contains
poisons that are very harmful to man and
animals.
The sclerotium is harvested with the rye
grain. The grain is ground into flour,
made into bread and is eaten by people.
Eating the contaminated bread results in
a disease called Ergotism.
ERGOTISM OFTEN RESULTS IN DEATH.
17. Ergot of Rye
The scelotia also contains hallucinogenic
compounds. People that eat ergot often see
Fire.
In the middle ages, people called the vision
of fire induced by Ergot
Holy Fire or St. Anthony’s Fire
Ergotism can also cause abortions and
gangrene.
THIS PLANT DISEASE IS STILL KILLING
PEOPLE IN THE WORLD TODAY
18. Black Stem Rust of Wheat
1916 - Destroyed 300 million
bushels of wheat in the
United States and Canada
1935 - Destroyed 135 million
bushels in Dakotas and
Minnesota
SPORATIC EPIDEMICS STILL COST NORTH
AMERICAN FARMERS BILLIONS OF
DOLLARS
20. Southern Corn Leaf Blight
1970 - An epidemic caused a 15%
loss of the U.S. corn crop.
This resulted in a one
billion dollar loss in the
United States.
This was enough corn that, if fed to cattle,
it would make 30 BILLION HAMBURGERS
22. Plum Pox Virus
Plum Pox is caused by a virus and is a very
serious disease that infects all stone fruit.
- It is estimated that 100 million stone
fruit trees are infected with the virus in
Europe.
- Infected trees become nonproductive
and must be removed. This results in
tremendous economic losses to stone
fruit producers.
24. Plum Pox Virus
In 1999, the virus was identified on
peach trees in Pennsylvania. This is the
first observation of the virus in North
America.
The virus was probably introduced into
the U. S. in an infected tree or budwood.
The disease is a major threat to stone
fruit production throughout North
America.
At present, plant pathologists and
regulatory agencies are trying to
eradicate the virus.
25. Plant diseases cause an
estimated loss of 8 billion
dollars per year in the
United States alone.
27. We rely upon Plant
Pathologists to provide
information about plant
diseases and how to
manage them.
28. A Plant Pathologist is a
professional who specializes
in plant health much as a
physician specializes in
human health or a
veterinarian in animal health.
30. Controlling plant disease
requires an understanding of
the agents that cause disease
as well as an understanding
of how plants are affected by
disease.
31. Through college courses in
botany, microbiology,
horticulture, crop science, soil
science, ecology, genetics,
biochemistry, molecular biology,
and physiology, students receive
the necessary background for
exciting careers in the
interdisciplinary science of plant
pathology.
32. Plant pathologists are
employed by colleges and
universities, state and federal
agencies, industrial firms,
international institutes, and
as private practitioners.
