This document discusses plant disease and its control. It defines plant disease as an abnormal condition that negatively impacts the structure or function of a plant, caused by pathogens. It then categorizes common plant diseases as bacterial, fungal, or viral. The document outlines three main methods to control plant diseases: biological, chemical, and physical control. For biological control, it describes using microorganisms like bacteria or fungi to directly kill pathogens or compete with them for resources. Chemical control involves using compounds like Bordeaux mixture. Physical control removes pathogens mechanically, such as by mowing or tilling. It also briefly defines quarantine laws as restrictions on agricultural transport to prevent introducing new pests or diseases.

1. PLANT DESEASE AND IT’S
CONTROL
PRESENTED BY
SAIKAT JANA
SEM-IV
DEPT. OF BOTANY
NARAJOLE RAJ COLLEGE

2. WHAT IS PLANT DESEASE
Plant desease is a particular abnormal condition that negatively
effects the structure or function of all or part of a plant, caused
by particular pathogens.
E.g.–
Stem rust of wheat Late blight of potato Tobacco mosaic desease

3. PLANT DESEASE
BACTERIAL FUNGAL VIRUL
Aster yellows
Bacterial wilt
Blight
Canker
Crown gall
Rot
Smut
Scab
Rust
Rot
Damping off
Club root
Leaf blister
Anthracnose
Blight
Canker
Black knot
Curly top
Mosaic
Psorosis
Spotted wilt
Scab
TYPES OF PLANT DESEASES

4. CONTROL OF PLANT DESEASES
Desease control is very important to keep the plant
species from extinction.
Plant deseases are usually controlled in three ways―
i. Biological control
ii. Chemical control
iii. Physical control

5. BIOLOGICAL CONTROL
This is the method of protection of plants directly by total or
partial destruction of pathogen population by microorganisms.
PROCESS OF BIOLOGICAL CONTROL
1. Direct mechanism
Direct lysis or killing of pathogen by biocontrol agent.
This is two types―
i. Antibiotics
ii. Parasitism

6. i. Antibiotics
Antibiotics are microbial toxins that can, at low
concentration, poison or kill other microorganisms.
Volatile antibiotics
Hydrogen cyanide
Aldehydes
Alcohol
Ketones
Sulfides
Non volatile
antibiotics
Polyketides
Heterocyclic nitrogen
compounds

7. ii. Parasitism
This is direct utilization of pathogens as source
nutrients.
Mycoparasitism refers to association in which a
parasitic fungus live as a parasite to another fungus

8. 2. Indirect mechanism
Exclusion of plant pathogen as a result of the
presence, activity or products of biocontrol agents.
This is two types―
i. Competition
ii. Induced systemic resistance (ISR)

9. i. Competition
• Exclusion of pathogens by biological control
agents via competition for space or nutrients.
• Production of substances for nutrient acquisition.
ii. Induced systemic resistance (ISR)
It also known as systemic acquired resistance
(SAR), resistance in plants to varieties of pathogens
induced by the presence or products of biocontrol
agents.

10. ISR biocontrol agents may be―
● Necrogenic pathogen (applied on leaf)
● Non-pathogenic bacteria (applied to root or seed)
● Metabolites of pathogenic or saprophytic bacteria.

11. Application method
There are five application methods of ISR―
Seed treatment Seedling dip method

12. Soil drench Foliar sprey Irrigation drips

13. CHEMICAL CONTROL
This is the process where plant deseases are
controled by chemical compounds such as―
● Bordeaux mixture
● Burgundy mixture
● Thiram
● Ferbam
● Ziram

14. PHYSICAL CONTROL
Physical control is the removal of weeds by
physical or mechanical means, such as mowing,
grazing, mulching, tilling, burning etc.

15. WHAT IS QUARANTINE LAW
A legal restriction on movement of agricultural
commodities for the purpose of exclusion, prevention or
delay in the establishment of plants, pests and deseases in
the area where they are not present.
Plant quarantine is this designed as a safe guard
against harmful pests/pathogens exotic to a country or a
region.

16. THANK YOU