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What is Plant Pathology or Phytopathology

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					What is Plant Pathology or Phytopathology?

Plant Pathology or Phytopathology is the study of plant diseases.

Did you know that plants have diseases and get sick just like people and animals do?

Most people don’t realize that plants are affected by infectious diseases caused by living organisms (called Plant Pathogens).

Infectious plant pathogens include fungi, bacteria, nematodes, viruses, and parasitic plants.

Plant Diseases are also caused by non-living or abiotic causes such as air pollution, nutrient deficiencies and various environmental factors.

Are Plant Diseases Important?
YOU BET THEY ARE!!!

All of our food, much of our clothing, building materials, and much of the beauty in nature is provided by plants.

Plant diseases are a constant threat to the world’s food and fiber crops, forests, and landscape plants.

Throughout history, plant diseases have been responsible for the death and suffering of millions of people and countless animals.

A few examples of devastating diseases are:
1. 2. 3. 4. 5. 6. 7. Potato Late Blight Ergot of Rye Black Stem Rust of Wheat Southern Corn Leaf Blight Dutch Elm Disease Bacterial Canker on Citrus Plum Pox Virus on Stone Fruit

All of these are infectious diseases caused by plant pathogens.

Let’s take a closer look at a few of these important plant diseases

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

Late Blight on Potato Tubers

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.

Ergot of Rye (note dark sclerotia)

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

Black Stem Rust of Wheat
1916 Destroyed 300 million bushels of wheat in the United States and Canada Destroyed 135 million bushels in Dakotas and Minnesota

1935 -

SPORATIC EPIDEMICS STILL COST NORTH AMERICAN FARMERS BILLIONS OF DOLLARS

Black Stem Rust of Wheat

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

Southern Corn Leaf Blight

Susceptible Plants

Resistant Plants

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.

Plum Pox Virus

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.

Plant diseases cause an estimated loss of 8 billion dollars per year in the United States alone.

What Can We Do About Plant Diseases?

We rely upon Plant Pathologists to provide information about plant diseases and how to manage them.

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.

Controlling plant diseases and keeping plants healthy is the main objective of a plant pathologist.

Controlling plant disease requires an understanding of the agents that cause disease as well as an understanding of how plants are affected by disease.

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.

Plant pathologists are employed by colleges and universities, state and federal agencies, industrial firms, international institutes, and as private practitioners.

Most Plant Pathologists are members of
The American Phytopathological Society (APS)

APS is an international scientific organization devoted to the study of plant diseases and their control.

The society has a membership of nearly 5000 plant pathologists and other scientists located in 80 countries worldwide.

The common goal of APS and Plant Pathologists worldwide is to develop and promote knowledge about plant diseases and their control.

We should all remember that we need HEALTHY PLANTS in order to have HEALTHY AND HAPPY PEOPLE.


				
Lingjuan Ma Lingjuan Ma
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