agro chemical

1. Don Bosco College of Agriculture
D o n B o s c o C o l l e g e o f A g r i c u l t u r e
(Affiliated to Goa University)
Welcome
Date: 19th February , 2020

2. LECT 23-24 : Classification of agro chemicals Agro-chemicals
The chemicals used in agriculture to maintain or to increase the crop production.
They are grouped as
1. Plant production chemicals - Fertilizers
2. Plant protection chemicals - Pesticides
3. Adjuvants, synergists - Plant growth regulators.
Pesticides
Any substance or mixture of substances used to prevent, destroy, repell or mitigating any
insects, rodent, namelodey, fungi, weed or any other form of terrestrial or aquatic plant or animal
life or microorganisms.
Pesticides is a general term which includes all the chemicals used as insecticides, fungicides,
herbicides etc.
Pesticides means any substance intended for preventing, destroying, attracting, repelling or
controlling any pest including unwanted species of plants or animals during production storage,
transport, distribution and processing of food agricultural commodities or animal feeds or which
may be administered to the animals for the control of ectoparasites.

3. Classification of pesticides
1. Acaricides - ticks and mites Ex. Sulphur and lime sulphur
2. Algicides - Algae and other aquatic vegetation Ex. Copper sulphate
3. Antiseptics - Non metals from microorganisms
Ex. Phenol, mercuric chlorosis
4. Arboricides - Undesirable arborell (Vegetative part) and bushy
vegetation. Ex. Sulphuric acid, copper sulphate.
5. Bactericides - Bacteria and bacterial diseases
Ex. Penicillin, streptomacin.
6. Fungicides - Plant diseases caused by various fungi.
Ex. Bordeax mixture
7. Herbicides - Control of weeds Ex 2-4-D, 2-4—5-T, Diurea.
8. Insecticides - Harmful insect Ex Endosulphan, carbaryl.
9. Molluscides - Climacides – soft bodjed insects like snails and slug
Ex. Metal dehyde.
10. Nematicides - Control of nematode
Ex. Methyle bromide and other fumigants.
11. Zoocides - Control of rodents
(Rodenticides) Ex. Zinc phosphate, vartarin.
12. Pesticides - to kill the fish Ex. Rotenoue.

4. Adjutants and others
1. Chemosterilants - Used to reduce or completely suppress the
reproductive ability of insects Ex. Abholate, Treatamine.
2. Plant growth regulators – used for regulate the growth of plant or
supress the growth, rooting, ripening of fruits etc. Ex. G.A., IAA, IBA, Cycocel,
Ethapon.
3. Defoliants - Removal of leaves. Ex. Sodium chlorate, Magnesium
chlorate, sodium polyborate and folex.
4. Repellants - For repelling insects Ex. Delphone, Indalone.
5. Attractant - For attracting insects Ex. Muscalure, Disparlure

5. LECT 25-27 : Botanical insecticides (neem) pyrethrum, synthetic Pyrethroids,
Synthetic pyrethroids.
Pyrethroids are essentially ester compouonds Attempt to replace the ester with other linkages had
reduced the inescticidal activity.
Type I – Pyrethrins, allethnins, resmethrin, phenothin, permethrin and oxime others.
Type II - Expermethrin, fenvalerate, deltamethrin.
Insecticides
Definitions – Chemicals used for the control of harmful insects.
Classification of insecticides
A)On the basis of chemical nature
a.Inorganic – Ex – arsenates, fluorides compounds.
b.Organic insecticides.
1.Oils and soaps – Petroleum products
2.Plant origine – Nicotine, Geraniol, pyrethrum and Rotenon.
3.Synthetic
a.Chlorinated hydrocarbons – DDT, HCH, Heptachlor, aldrin etc. (CH & Cl)
b.Organophosphorus (C, H, O &, P, S) Malathion, parathion and Dematphosphamidon.
c.Carbonate insecticides – Carboryl, carbofuran. d.Pyrethoids – Allethrin, permethrin, eltametrin.
e.Miscellaneous Insecticides – Karathane, DNOC.

6. Plant Originated Insecticides
Nicotine – 3 (1-Methyl –2 pyrrolidyl) pyridine) Alkaloid present in the leaves of
Nicotiana sp.
Nicotine (C10H14N2) – (N-methyl-2, 3 (Pyridyl) Pyrollidine ring give structure of
Nicotine.
Occurrence – occurs from solanaceous genera plant i.e. Tobacco
propperties – Give properties.
Mode of action – contact insecticides and also fumigant. It enters in
insect through spiracle in the tracheal system. Nicstice is highly toxic by
injection, inhalation and skin absorption. It is an automatic blocking agent and
acts like acetyl choline but only at gunglia and neuro muscular junctions,
initially stimulating then depressing then symptoms are ercitation conclusion
paralysis and death.

7. Pyrethrum :
a) Structure : C21H28O3
b) Occurrence : Flower heads of chrysanthemum genera. Active material is
pyrethrin
c) Mode of action : Quick knock down action of induction of temporary
paralysis. The symptoms follow the typical pattern of nerve poison. Pyrethrum affect
central nervous system interfering the Na+ and K+ ionic potential.
Pyrethrins - occurs in the roots of Derris elliptica pyrethrins derived from dried
flowers of chrysanthemum. Chemically pyrethnins are organic esters formed by the
combination of two carboxylic acids and three keto alcohols.

8. 1. Synthesis
2. The preliminary screening
3. Formulation
4. Toxicity studies
5. Metabolism studies
6. Residue studies
7. Registration
8. Promotion
9. Plot plant studies
10. Commercial.
LECT 28-30 : Steps in development of pesticides.(Important)

9. Synthetic organic insecticides, Chlorinated hydrocarbons -- Aldrin chlordane,
heptachlor, DBCP.
Organophosphates – Diazinon, disulfton, malathion, methyl parathion.
Carbamates – Carbayl, carbofuran, methomyl, aldicatb, dithiocarb, oxamyl

10. 1. Organochlorine insecticides
It includes substances which vary in their chemical structure but because of their common
properties in high insecticidal activity and chemical and biological persistence, these are groped in to
one. Chemical these can be further subdivided in to four major groups.
Classification of organochloride insecticides
a) DDT and relatives - DDT, Perthane, Rothane (DDD)
b) Benzene derivatives - BHC, Lindane
c) Cyclodiencs - Aldrin, dieldrin, Endrin, Chlordane, Budosulfan, Heptachlore.
d) Polychloroterpenes - Toxaphene, storbane.
i.DDT – (Dichlorodiphenyl trichlorocthane)
a.Structure – Give structure – 1, 1, 1-trichloro –2, 2-bits (P-chlorophenyl) ethane. First synthesised by
‘Zeidler in 1874.
ii) BHC – Benzene hexachloride, C6H6Cl6. Hexachloro cyclohexane, 1, 2, 3, 4, 5, 6 –
Hexchlorocyclohexane. Also called as HCH (Hexachloro cyclohexane).
First synthesized by Micheal Faraday in 1825.
iii) Cyclodienes – Insecticides having cyclic structure containing two double bonds. Prepared by
Diels – Alder reaction.
Endosulpan (Thiodan) (5,H6 Cl6SO3.

11. Mode of action of organochlorides
Chlorinated hydrocarbons are all neurotoxicants. Their application cause
inhibition or inactivation or inter ferous in the functioning of Na-K. ATPase and Ca-ATPase
enzymes which are required for proper a balance of Na and K in axon. The imbalance of
these enzymes results in prevention of normal transmission of nerve imbalse in insects
and mannuals. Eventually the neutrons five imbalses spontaneously causing muscles to
twitch this may lead to convulsion and death.

12. They are the esters of different alcohols and phosphorus acid. They econtain C, H, O, P, S, N and
Cl molecule in their structure.
Compounds of this group possessing insecticidal action can be classified on the basis of
following acid derivatives.
a) Phosphoric acid - Dichlorovas, phosphamidon.
b) Phosphoric acid - EPN
c) Thiophosphoric acid - Parathion, Methyl demetan.
d) Dithiophosphoric acid - Malathion, Thimet, Dimethoate.
e) Pyrophosphotic acid - TEPP, Schradden
f) Others - Jsopestox
I)Phosphamidon – (Dimecron) C10 H19 O5 NPCl)
a.Structure – Give structure (O, 0-dimethyl – 0- (2 – chloro – Al- N diethylcarbamyl)- methyl vinyl
phosphate).
.
ii)Parathion – (Thiophos) (10H14 NO5S)
Organophosphate insecticides –

13. Mode of action of organophosphates :
Organophosphate insecticides affect the enzyme choline esterase (ChE) which is
responsible for removal of acetyl choline (Ach) present in synapse (gap between nerve cell).
This results in to continuous transmission of nerve impulses and loss of coordination of
nerves and other organs giving rise to rapid twitching of voluntary muscles and finally
paralysis of vital organs including langs. Thus failure of respiration due to paralysis of lungs
is the main cause of death. The reaction of inhibition of choline – esterase is irresersible so
OPS are more total compared to carbomates.

14. Carbamate insecticides
Carbamate insecticides are esters of carbamic acid (HO-C – NH2). They have an OCON = group in
the molecule. They are esters of methyl and dimethyl carbamic acids. They are classified in to 3
groups as
a)A-methyl carbomate - carboryl, carbofuran
b)N-N-dimethyl carbomate – Isolan and Dimetelan
c) Oxime carbamate – Aldicarb, methomyl
1)Carbaryl (Sevin) – C12H11O2N – 1-Naphyl-N methyl carbamate give structure and properties.
2)Carbofuran (Furadan) - C12H18NO3
-
2, 3 dihydro 2, 2-dimethyl – 7 – benzoturanyl – N methyl carbamate
3)Aldicarb (Temik) C7H14SN2O2
2-methyl-2 (methylthio) propionaldehyde 0-(methyl carbamate) Oxime
Mode of action – Similar to organophosphorus insectides.

15. Lect 31 and 32: Herbicides – Major classes – properties and uses
A herbicide in the broadest sense of word is any compound that is capable of either killing or severely injuring plants
and may thus be used for elimination of plant growth or killing of plant parts.
Classes of herbicides based as
1.Method of application---Pre-emergence Post emergence
Mote of action -------Contact Herbicides Translocated herbicides Residuel herbicide
Based up an chemical ---------- affimit and agricultural simulation
Inorganic Organic
CLASSIFICATION OF HERBICIDES
1) Based on Method of application
i) Soil applied herbicides: Herbicide act through root and other underground parts of weeds. Eg. Fluchloralin
ii) Foliage applied herbicides: Herbicide primarily active on the plant foliage Eg.Glyphosate, Paraquat
2) Based on Mode of action
i) Selective herbicide: A herbicide is considered as selective when in a mixed growth of plant species, it kills some
species without injuring the others. Eg. Atrazine
ii) Non-selective herbicide: It destroys majority of treated vegetation Eg. Paraquat 3 Based on mobility
i) Contact herbicide: A contact herbicide kills those plant parts with which it comes in direct contact Eg.
Paraquat
ii) Translocated herbicide: Herbicide which tends to move from treated part to untreated areas through xylem /
phloem depending on the nature of its molecule. Eg. Glyphosate

16. 3 Based on mobility
i) Contact herbicide: A contact herbicide kills those plant parts with which it comes in direct contact Eg. Paraquat
ii) Translocated herbicide: Herbicide which tends to move from treated part to untreated areas through xylem / phloem
depending on the nature of its molecule. Eg. Glyphosate
4) Based on Time of application
i) Pre - plant application (PPI) Application of herbicides before the crop is planted or sown. Soil application as well as foliar
application is done here. For example, fluchloralin can be applied to soil and incorporated before sowing rainfed groundnut
while glyphosate can be applied on the foliage of perennial weeds like Cyperus rotundus before planting of any crop.
ii) Pre – emergence-----Application of herbicides before a crop or weed has emerged. In case of annual crops application is
done after the sowing of the crop but before the emergence of weeds and this is referred as pre-emergence to the crop
while in the case perennial crops it can be said as pre-emergence to weeds.
iii) Post – emergence Herbicide application after the emergence of crop or weed is referred as postemergence application.
When the weeds grow before the crop plants have emerged through the soil and are killed with a herbicide then it is called
as early postemergence. For example spraying 2,4-D Na salt to control parasitic weed striga in sugarcane is called as post-
emergence while spraying of paraquat to control emerged weeds after 10-15 days after planting potato can be called as
early postemergence. Eg. Glyphosate, Paraquat, 2,4-D Na Salt.
iv) Early post emergence: Another application of herbicide in the slow growing crops like potato, sugarcane, 2-3 week after
sowing is classified as early post emergence.

17. General mode of action of herbicides.
1.Photosynthetic poisons
a.Interfere with Hill’s reaction – In photolysis of water here is evolution of oxygen which is interfered by
herbicides like triazines, carbamates, urea derivatives then interference will dead to no supply of
oxygen.
b.Some interference in Electron transport chain – herbicides like paraquat, diquat, Bipyrillidium, after
several stages ……….
2.Those interfere with cellulor metabolisms – herbicides lil 2-4-D, phenoxy acids and benzoic acid series
results in to an controlled growth leading to collapse of xylem, phloemce and plant die.
3.Interference in the protein metabolism – herbicid like butachlor interfere in protein metabolisum
resulting in stunted root growth there by shortening of stem, etc and plant may die.
4.Uncoupling of oxidative phosphoralation – herbicides like DNOC, MSMA and even arsenic containing
herebicides inter in the oxidative phosphorelation process and there is no format of ATP. Plant does not
set emerge and it dies.

18. Lect 33-34: Fungicides
Fungicides are chemicals that have the ability to reduce or prevent the
damage caused by fungi in plants and their products.
Fungicides are biocidal chemical compounds used to kill parasitic fungi or
their spores.
Classification of fungicides
1. On the basis of use
2. Protective Curative
3. Eradicants

19. A . Protective fungicides : They prevent fungal infection by sporocidal activity.. E.g.
Sulphur
B. Curative fungicides : It penetrate cuticle and kill young fungal mycelium growing in the
epidermis and this prevents further development of fungal growth. E.g. Organomercurials
C. Eradicant fungicides : . They are agents that make control of fungus even after the
symptoms become visible and that kill both newly developed spores and the mycelium.
E.g. Systemic fungicides
2. On the basis of sources of raw material
A. Inorganic fungicides : It includes sulfur powder, lime sulfur, copper sulfate, mercuric
chloride etc…
B. B. Organic fungicides : Ziram, Zineb, mancozeb etc….

20. Chemistry, use, and mode of action of
1.Carbendazim
2.Carboxin
3.Captan
4.Tridemorph
5.Copper oxychloride
1. Carbendazim : IUPAC Name Methyl 1H-benzimidazol-2-ylcarbamate
2. Carbendazole
3. Chemical formula : C9H9N3O2 Melting Point (M.P) : 302-307˚ C
4. Uses . It is used to control plant diseases in cereals, and fruit including citrus, bananas,
strawberries, pineapple etc.. Mostly used to control Botrytis, Gloeosporium rots,
powdery mildews and apple scab
5. Mode of action Carbendazim works by inhibiting the development of fungi probably by
interfering with spindle formation at mitosis (cell division). affects the nervous system
through their main metabolite, carbon disulfide.

21. Captan :
IUPAC Name : 2-(trichloromethylsulfanyl)-3a,4,7,7a-tetrahydroisoindole-1,3-dione
Others
Name : Captaf Hexacap Captab
Properties . Odorless white crystalline powder Melting point 172.5˚ C Slightly
soluble in ethylene dichloride Noncorrosive in nature
Uses : Captan is predominantly used in agriculture as a fungicide on a wide variety
of fruits, vegetables, and ornamentals on plant seeds, and also on food crop
packaging boxes. Captan is also used in cosmetics pharmaceuticals oil-based
paints wallpaper paste Plasticizers rubber stabilizers textiles etc……
Mode of action . Captan is non specific thiol rectant with protective and curative
action that works by inhibiting respiration of numerous species of fungi and bacteria
The mechanism of action may involve the degradation of captan in to the short lived
thio phosgene which is highly reactive with thiols and other functional group

22. Tridemorph
Name 2,6-Dimethyl-4-tridecylmorpholine
Molecular Formula C19H39NO
Properties Boiling point : 134˚ C Yellow oily liquid .
Uses : fungicide used to control Erysiphe graminis
moderately hazardous
Mode of action
Inhibit protein and RNA synthesis
Inhibit lipid synthesis and
Often inhibit sterol biosynthesis

23. Copper oxychloride
Name Dicopper Chloride Trihydroxide
Properties Not flammable Highly toxic fungicide Insoluble in water
Uses : Copper Oxychloride is for the control of fungal and bacterial diseases
in fruit and vegetable crops, citrus, stone fruit, pome fruit and ornamentals.
Key Features and Benefits . • Economical control of a wide range of fungal
and bacterial diseases in many crops and situations • pH neutral product and
ultra-fine particle size with majority of particles less than or equal to 2-
micron diameter • Free flowing product for easy mixing and application •
Can be applied in tank mixes with a wide range of other chemicals and/or
fertilisers.
Mode of action : . Interfers with the enzyme system of mycelium and
spores.

24. Lect 35: Plant growth regulators
Plant growth Regulators : Substances that cause the acceleration or
retardation of the rate of growth or rate of maturation.
Defoliants : substances that cause the plant leaves to die and fall away.
Dessicants : substances that cause to drain moisture out of plants causing them
to dry.
Attractants : Substances that attract pests.
Repellents : substances that repels the pest from a treated plant.
Plant growth regulators are chemicals used for causing acceleration or
retardation of the rate of growth or rate of maturation of the plants and are
legally considered as pesticides

25. The plant growth regulators are classified into following groups.
1) Auxins
2) Gibberelins
3) Cytoleinns
4) Inhibitors and retardants.
5) Ethylene generators.
A) Phyto-hormones : Defined as organic compound of than nutrients which
in small amounts, promote, inhibit otherwise modify the plant physiological
process.

26. Auxins – Group of compound that induce elongation in shoot cells e.g. FAA, IAA,
NAA.
Gibbrellins – Having gibbane skeleton, stimulate cell di or cell elongation or both eg.
G.A.
Cytokinxins – Derivatives of adenine. They induce cell and cell differentiation. eg.
Zeatin, Zip, kinetin, 6-Benzylamino.
Ethylene generators – They induce uniform ripening eg. Ethephon.
Inhibitors : Inhibit physiological processes and retard and retardants growth in plant.
e.g. Benzoic acid, cinnamic acid, Gallic acid Abscisic acid, cycocel,.
Classification of phyto-hormones

27. i) Defoliants ; Chemicals that accelerate leaf fall. Eg.
A) Inorganic salt – sodium and magnesium chlorate. Sodium polyborate.
B) Organo phosphate – DEF (Tributyl phosphorothieate) Folex.
C) Bipyrillidium – Pearaquat.
ii) Dessicants – chemicals designed to hasten drying of crop parts eg.
Arsenic acid (H2 ASH4)
iii) Synergist or Activators – An material that are used with insecticide
to synergiso or enhance the activity of insecticide. Eg. Piperonyl butoxide
(PBO), sesamex, valone MGK 264.
iv) Microbials Insecticides : Microorganisms which are used for control
of insects. Eg. Bacillus thuringensis (BT) desease causing bacterium.
Agrochemicals with special effects.

28. Lect 36 : Fertilizer control order 1955
An order issued by the Government of India under powers conferred by
Section 3 of the Essential Commodities Act 1955, under the powers, the
Government controls the production, marketing, price and quality of
fertilizers.
There are 39 Clauses of this order covering definitions, prices, registration of
dealers and fertilizer mixtures, regulation on manufacture cell packing
requirement, disposal of non-slandered fertilizers, enforcement authority,
analysis of samples, etc.
The schedule I of the order includes detailed specifications of fertilizers
covered by it.
In schedule II detailed procedure regarding sampling technique and methods
of analysis is given.

29. Insecticide Act 1968 effective from 1/08/1971
The main objective of the Insecticide Act is to regulate the import, manufacture, safe
transport, distribution and use of insecticides with a view to prevent risk to human beings,
animals and for matter connected herewith.
All the regulations of the Insecticide Act were brought into force with effect from 1st
August, 1971, which was passed in 1968.
Due to legal reasons, the act was called Insecticide Act and not pesticide Act under Section
93 (C) the word insecticide means.
(1) Any substance specified in the schedule.
(2) (2) Any other such substances including fungicide and weedicides may be included after
consolation with the board and central Government.
(3) Any preparation containing one or more of such substances.