The document discusses the mechanisms of action for different types of pesticides. It explains that stomach poisons kill pests by being ingested and absorbed in the blood, while contact insecticides kill on direct or indirect contact by penetrating the body. Fumigants can be applied in enclosed areas to surround and enter the breathing pores of insects. It also compares contact and systemic fungicides, noting that contact fungicides act preventatively at the application site while systemic fungicides can be absorbed and act both preventatively and curatively throughout the plant. Resistance is a greater risk for systemic fungicides which have a single site of action.

1. P R E P A R E D B Y
M R S . P O O J A K H A N P A R A
A S S I S T A N T P R O F E S S O R
A P I P , J A M N A G A R
NATURAL
PESTICIDES

6. Mechanism of action of pesticides
 Broad categories – As
 1. Stomach poisons:
 Kill by being taken into stomach, absorbed in the
blood and leads to the death of the pest due to the
toxic action.
 2. Contact insecticides:
 Kill by direct or indirect contact with the insect or
sometimes it penetrates inside the body and causes
oxidation and suffocates the insect.

7.  3. Fumigants:
 Can be applied only in enclosed areas where it
surrounds the insect, enters their breathing pores
and kills.

10. Contact/Protectant Systemic
 Adsorbed
 Immobile
 Preventive
 Multi site of action
 Few problems with
Resistance
 Eg: Mancozeb, Maneb,
Sulfur, copper
 Absorbed
 Mobile
 Preventive + Curative
 Single site of action
 Resistant fungi strains could
develop
 Eg:-Metalxil,
Dimethomorph, Thiphenate
methyl.
Contact vs Systemic Fungicides

11. Types of fungicides