Plant Disease Control

Classification of plant Disease control methods :

The control measures for plant diseases have been classified into two categories

a) Prophylaxis

b) Immunization

A) Prophylaxis:

Include methods which protect the plant from the attack and infection by the pathogen or from the environmental factors which favour disease development.

These methods have further been divided into three sub categories

A1) Exclusion 

Method which prevents a disease from entering into a new area

For example , 

Quarantine and Insection 

A2) Eradication

Measure taken for the elimination of the pathogen after its establishment on the host It includes crop rotation, sanitation, elimination of alternate and over wintering hosts 

A3) Direct Protection:

B) Immunization

Immunization deals with development of disease resistance in plants 

General Principles of plant Djsease Control

1) Avoidance of the pathogen

2) Exclusion of the inoculums

3) Eradication of the pathogen 

4) Protective measures

5) Development of resistance in the host 

6) Therapy of diseased plant

1) Avoidance of the lathogen

It includes the following measures

a) Selection of Geographical area

A geographic area is selected on the basis of the favourable temperature and humidity requirement for a particular crop

b) Selection of field : Many soil borne diseases are controlled by proper selection of the field. Water drainage is also taken care of while selecting the field

 c) Choice of time of sowing:

d) Disease escaping varieties:

e) Selection of seed: 

To avoid seed borne diseases healthy abd disease free seeds are essential

f) Modification of cultural practices:

2) Exclusion of Inoculum : 

It includes the following methods:

a) Seed Treatment:

   Refers to the Application of fungicide , insecticide or both to the seeds to disinfect and disinfest them from seed borne or soil borne pathogenic organisms 

Benefits of seed Treatment:

1) Prevention of spread of plant diseases 

2) Improve germination 

Physical methods:

Jensen for the first time used heat to control internal infection of potato tubers by late blight fungus 

(Phytophthora infestens)

Hot water treatment method of Jensen was developed in 1887 which was used to control loose smut disease of wheat, barley and oat .Hot water treatment is also effective in the control of nematodes.

Solar energy treatment:

To control loose smut was first developed by Luthra .In this method seeds are first rinsed or soaked in water for 4-5 hrs before drying them in scorching sun 

Hot air treatment:

For control of virus in propagating stocks was first developed by Kunkal in peach yellow 

Chemical methods:

Seed treatment with fungicide before transplanting is done with following objectives:

1) To control disease caused by seed borne infection

2) To protect germinating seeds or seedlings from the attack of soil borne pathogens

Types of seed Treatment:

1) Seed disinfection:

This type of seed Treatment is for the eradication of such pathogens which are internally seed borne i.e. they are established in the seed coat or deep tissues in the seed.

Examples - loose smut of wheat and barley, Rhizoctonia disease of tomato 

Earlier only physical measures like hot water or solar energy treatment was used for the eradication of such diseases. 

But now a days a systemic fungicides like Plantavax / Oxycarboxin , vitavax , carboxin , Bavistin are used for the purpose.

2) Seed Disinfestation : 

Distruction of fungal or bacterial pathogens present on the seed surface is called seed Disinfestation. The fungicides used in this process are either in powder or wettable form 

Many externally seed borne diseases such as - covered smut of barley or oat , loose and grain smut of jowar , wheat bunt  can be controlled by seed Disinfestation

Fungicides used in

Copper sulphate, Copper carbonate , Casesan , panogen

3) Seed Protection: Protection of seeds from seed borne pathogens during the process of seed germination is called seed protection.

Fungicides used as seed prorectants are - Captan , thiram , Arasan , Agrosan GN , Folpet

a) Systemic fungicides are used for seed disinfection, seed Disinfestation and seed Protection

Examples of Systemic Fungicides 

Oxanthin derivatives Plantavax and Vitavax , Benlate , Bavistin

Plant Quarantine: A plant quarantine can be defined as a legal restriction on the movement of agricultural commodities for the purpose of exclusion, prevention or delay in the establishment of plant pests and diseases in areas where they are not known to occur

✍️Agricos

Vaishnavi Nimkar 🌾🌱