INTRODUCTION OF PLANT PATHOLOGY

Introduction to plant pathology

What is a plant disease

A plant disease is any abnormal condition that alters the appearance or function of a plant. It is a physiological process that affects some or all plant function. Disease may also reduce yield and quality of harvested product. Disease is a process or a change that occurs over time. It does not occur instantly like injury. Visible effects of disease on plants are called Symptom- any detectable change in color and   Sign – physical evidence of the pathogen.

What cause plant disease

Infectious plant disease is caused by living organisms that attack and obtain their nutrition from the plant they infect. The parasitic organisms that cause a disease is a pathogen.

EPIDEMIOLOGY

EPIDEMIOLOGY

What is Plant Disease Epidemiology?

        Plant disease epidemiology is the study of disease in plant populations. It is often looked at from a multi-disciplinary approach, requiring biological, statistical, agronomic and ecological perspectives.

HOW PATHOGENS ATTACK PLANTS

Pathogens attack plants through 4 methods : 
1. Mechanical force 
2. Chemical weapon
3. Microbial toxins
4. Growth regulators

A) Mechanical structures

2 special structures to penetrate plant surface :
i. Appressorium
ii. Haustorium

HOW DO PLANTS DEFENSE THEMSELVES

HOW DO PLANTS DEFEND THEMSELVES

To prevent further spread of infection, healthy plant cells around the site of infection will die.

Ø Plant defense mechanism

ü Structural defense

Physical barriers that inhibit pathogens from entering into the host cell

ü Chemical defense

Produce substances that either toxic to the pathogen or inhibit growth of pathogen

COMMON DISEASE OF MAJOR CROP

Plant disease are a significant yield and quality constraint for growers of broadcare crops. Plant pathogen can be fungal, bacteria, virus and nematodes and can damages plant parts above or below the ground. Below are the example of disease of oil palm, rubber, paddy and cocoa:   

DISEASE MANAGEMENT

   1.    Prophylactic Approach

Ø  Practices management that protect the host from pathogen or from environment that may encourage the development of disease.

CONTENT

CONTENT

      1.  Introduction of plant pathology 
     
      2.  Epidemiology
    
      3.  How pathogens attack plant

      4.  How plant defense themselves

      5.  Disease in major crop

      6.  Disease management