2. Fungicide [Latin word – Fungus + caedo (to kill)] or Fungitoxicant is
a chemical, which has the ability to kill the fungus.
Fungistat is a chemical, which inhibits the fungal growth temporarily.
The phenomenon of temporary inhibition is known as
fungistasis. e.g., Gliodin, Chloroneb
Antisporulant – A chemical, which do not affect the growth of
vegetative hyphae but inhibits the spore production is known as
antisporulant. e.g., Bordeaux mixture
3. History of fungicides
1000 BC – Homer, Greek poet mentioned sulphur with pest control
properties.
1761 – Schulthess first suggested CuSO4 to control stinking smut on
wheat seed.
1807 – Prevost (France) found effectivity of CuSO4 against stinking
smut of wheat.
1821 – Robertson found sulphur – effective against peach mildew.
1882 – Prof. P. M. A. Millardet developed Boredeaux mixture.
1887 – Mason (France) introduced Burgundy mixture
1934 – Tisdale and Williams reported fungitoxic activity of
Dithiocarbamates.
4. 1952 – Kittleson introduced captan as fungicide (Kittleson’s killer)
1966 – von Schleming and Marshal Kulka discovered systemic
fungicides (Oxathiin compounds)
1973 – Triazoles were introduced
1978 – Fosetyl-Al was introduced
India
1885 – Ozanne – first person to use CuSO4as a fungicide to control
sorghum smut
1904 – Lawrence (Pune) used Bordeaux mixture first time to
control Groundnut Cercospora spp.
1906 – Sulphur was first tested in grapes
1914 – Burns used HgCl2 first time to control R. solani in potato.
1925 – Hilton tested organomercurials first time to control of
sorghum smut.
1964 – Discovery of Aureofungin by Thirumalachar et al.
5. First generation fungicides
Copper based derivatives of Bordeaux mixture
(Copper fungicides)
Second generation fungicides
Dithiocarbamate fungicides
(organosulphur compounds)
Third generation fungicides
Systemic compounds
(Oxathiin, Benzimidazole and antibiotics)
Fourth generation fungicides
Ergosterol biosynthesis inhibitors (EBI)
(Triazoles, pyrimidines)
Fifth generation fungicides
Strobilurin fungicides
(Azoxystrobin, Trifloxystrobin)
6. Strobilurins represent a major development in fungus-based
fungicides extracted from the fungus, Strobilurus tenacellus.
Some common Strobilurins are azoxystrobin, kresoxim-methyl,
picoxystrobin, fluoxastrobin, oryzastrobin, dimoxystrobin,
pyraclostrobin and trifloxystrobin.
They have a suppressive effect on other fungi, reducing
competition for nutrients; they inhibit electron transfer in
mitochondria, disrupting energy metabolism and preventing
growth of the target fungi.
7. Fungicide formulations
Fungicides with raw or unformulated state are not suitable
for disease management. These concentrated chemicals (active
ingredients) may not mix well with water, may be chemically
unstable, may be difficult to handle and transport.
To improve the application effectiveness, safety, handling and
storage the inert ingredients (clay and solvents) are added and they
are called pesticide formulations. These inert or inactive ingredients
do not possess pesticidal activity and are added to serve as a
carrier for the active ingredients.
Pesticide formulation is a mixture of the active and inert ingredients.
8. Pesticide formulations consists of
the active ingredient that controls the target pests
the carrier, such as organic solvent or mineral clay
surface-active ingredients, such as stickers and spreaders
other ingredients, such as stabilizers, dyes and chemicals
that improve or enhance the pesticidal activity
9. Fungicides formulated commercially are of two types
viz., Liquid formulations and solid formulations.
i. Liquid formulations
a. Emulsifiable concentrates (EC or E)
b. Solutions (S)
c. Flowables (F) / Liquids (L)
d. Aerosols (A)
10. ii. Solid formulations
a. Dusts (D)
b. Granules (G)
c. Pellets (P or PS)
d. Wettable powders (WP or W)
e. Soluble powders (SP or WSP)
f. Water dispersible granules (WDG) or Dry flowables (DF)
Other formulations
Fumigants – Liquified gas
Repellants
Attractants
11. i. Liquid formulations
a. Emulsifiable concentrate (EC or E):
This common and versatile formulation contains the liquid
toxicant (a.i), one or more petroleum based solvents for the
toxicant and an emulsifying agent (an agent that allows the
product to be mixed with water to form an emulsion).
Incorporation of a small amount of an emulsifier (surface-
active material) into the mixture ensures emulsion with desired
stability, wetting and spreading characteristics. An emulsion is a
mixture of two or more liquids that are not soluble in one another.
When sprayed, the solvent evaporates quickly leaving a
deposit of toxicant from which the water also evaporates.
It contains between 25 and 75 per cent active ingredients
12. Emulsions
Emulsions are prepared when the active ingredient is not
soluble in water or other cheap solvent.
It is prepared by dissolving the active ingredient in small
quantity of solvent and emulsifying it in water to the required
degree of concentration.
The colloidal concentrate is prepared mechanically and
diluted with water for spraying.
Emulsions become unstable when stored for long periods and
are more expensive than water dispersible powders for
equivalent quantities of the active ingredients.
13. Advantages
Relatively easy to handle, transport and store
Little agitation is required
Not abrasive
Will not plug screens and nozzles
Little visible residue on treated surfaces
Disadvantages
Highly concentrated, making it easy for calibration errors
May cause phytotoxicity
Easily absorbed through skin
Solvents may damage rubber or plastic hose, pump parts, metal, etc
Flammable – should be stored away from open flame or heat
May be corrosive
14. b. Solutions
It contains the active ingredient, the solvent (carrier) and one or
more inert ingredients. These formulations form a solution that
will not settle out or separate once mixed.
Advantage: No agitation after formulation is added in water.
Disadvantage: Easily absorbed through skin
Special kind of high-concentrate solution is the ultra low volume
(ULV) concentrate (100 per cent a.i). ULV formulations are
applied without dilution with special aerial or ground equipments
to produce an extremely fine spray.
15. c. Flowables (F)/ Liquids (L)
Active ingredient (soluble solid) impregnated with inert
ingredients (clay) is ground to a very fine powder and then
suspended in a small amount of liquid.
Flowables should be constantly agitated to prevent the pesticide
from coming out of suspension and settling to the bottom of the
spray tank.
d. Aerosols (A)
Toxicants used in aerosols are dissolved in volatile petroleum
solvents. (a.i + solvent).
On release of pressure the liquid containing the toxicant
vapourizes and leaves a residue over the entire surface.
Aerosols have a low percentage of active ingredient and
therefore expensive. They are used mostly in glass houses.
16. ii. Solid / Dry formulations
a. Dusts
Dusts are the oldest and simplest solid formulations of fungicides.
Most of them are ready to use and contain low percentage of
active ingredients (10 % or less by weight)
They are prepared by mixing the toxicant with very fine dry inert
carrier made from talc, kaolin, diatomaceous earth, bentonite,
calcium silicate, hydrated silica, calcium carbonate, magnesium
carbonate, gypsum and lime.
For dusts, particles of 30 to 50 m are preferred.
They are light, easily carried by wind to a considerable distance.
17. Advantages
Mostly ready to use, with no mixing.
Easy to apply in small areas and require simple equipment.
Dusts are cheaper
Effective in hard to reach indoor areas.
Disadvantages
Easily drift off target during application
May irritate eyes, nose, throat and skin.
Does not stick to surfaces as well as liquid formulations do.
Dampness can cause clogging and lumping
Difficult to get an even distribution of particles on surfaces
18. b. Granules
Similar to dust except the particles are larger and heavier.
The coarse particles are composed of absorptive materials such
as clay, corn cobs, walnut shells or other minerals.
The fungicide is absorbed into the granule, coats the outside, or
does both.
The amount of active ingredient in granular formulation ranges
from 1 to 15%. Because of the size of the granular particles it is
safer (not inhaled) to apply than dusts or emulsifiable
concentrates.
Mostly applied to control weeds, nematodes and soil insects.
19. Advantages
Ready to use with no mixing involved
Due to greater weight very little drift occurs.
Fewer hazards to the applicator
May breakdown very slowly than WP or EC formulations
Disadvantages
Does not stick to foliage or other non level surfaces.
May need to incorporate into soil.
Require moisture to start pesticide action.
Proper coverage may be problem with this formulation.
Efficacy in soil depends on dosage, soil type, moisture,
method of application, rate of release of the toxicant,
type of crop and weather conditions.
20. c. Pellets (P or PS)
Similar to granular formulations but all the particles are of same
weight and shape in pellet formulations (uniformity in size).
d. Wettable powders (WP or W)
Wettable powders are formulated to be mixed with water and
sprayed on surfaces. They contain 5 to 95% (usually 50% or more)
active ingredient.
It is a finely ground formulation consists of active ingredient mixed
with inert material (filler) such as kaolin, a wetting agent and a
suspending agent. In addition, spreader- sticker is sometimes
desirable, especially on plants with glossy or waxy leaves.
21. Advantages
Easy to transport, store and handle.
Less phytotoxic than emulsifiable concentrates.
Less skin and eye absorption than EC and other liquid forms
Disadvantages
Inhalation hazard when handling the concentrated products.
Require good and constant agitation
More abrasive to spray pumps and nozzles
Difficult to mix in hard or alkaline water
Often clogs nozzles and screens
Residues may be visible
Wettable powders should never be used without dilutions
22. e. Soluble powders (SP or WSP)
Like wettable powders, however dissolves readily in water and
forms a true solution.
Some agitation is needed to get soluble powders into solution.
But after they are dissolved no agitation is needed.
The amount of a.i varies from 15 to 95% (usually 50% or more)
23. f. Water dispersible granules or Dry flowables (WDG or DF)
Similar as that of wettable powders. But the active ingredient is
formulated as granule-sized particles.
WDG is easily mixed with water and applied.
A wetting agent is usually present in most water dispersible
granular formulations but addition of a spreader-sticker is
desirable when it is sprayed on plants with glossy or waxy leaves.
It needs constant agitation to keep them suspended in water.
It contains the high percentage active ingredient.
They have the same advantages and disadvantages of WP
except that WDG are more easily mixed and measured and have
less inhalation hazard to the handler.
24. Liquified Gases (LG)
Fumigants when placed under pressure turn into a liquid.
Liquified gases are stored in metal bottles under pressure and
are released into the soil by injection.
25. Synergists and auxiliaries or adjuvants
Adjuvants are chemicals that do not possess pesticidal activity and
are either pre-mixed in the pesticide or added to the spray tank to
improve mixing or application or to enhance the safety and
efficiency of the pesticide.
Adjuvants are designed to perform specific functions including
wetting, spreading, sticking, reducing evaporation, reducing
volatilization, buffering, emulsifying, dispersing, reducing spray drift
and reducing foaming.
26. Type of Adjuvants
Surfactants: Also called wetting agents and spreaders, physically
alter the surface tension of a spray droplet.
Alter the wetting, spreading and dispersal properties of spray
droplets.
They enlarge the area of pesticide coverage, thereby increasing the
pest’s exposure to the chemical.
Emulsifiers: allow petroleum-based pesticides (EC) to mix with water
27. Wetting agents: allow wettable powders to be mixed with water.
Wetting agents are materials which facilitate contact between
spray and sprayed surface.
They reduce the surface tension of the spray liquids and improve
the surface of contact and help to spread. E.g., Teepol, Tergitol
and Triton-AE
Spreaders: allow pesticides to form a uniform layer on the treated
surface.
Like wetting agents, spreading agents or spreaders also improve
the contact between spray materials and plant surface. They help
in the good coverage of the fungicide. e.g., Soap, saponins,
mineral oil, terpene oil.
28. Stickers: Increases the adhesion of solid particles to target
surfaces. Allow pesticides to stay on the treated surface.
Decreases the amount of pesticides that washes off during
irrigation or rain.
Reduces evaporation and slow down the degradation by sunlight.
e.g., Milk casein, gelatin, starch, gum arabic. Milk casein and
gelatin also act as good spreading and wetting agents besides
acting as stickers.
Penetrants: allow the pesticide to get through the outer surface to
the interior of the treated area.
29. Dispersing agents: Dispersing agents or deflocculating agents
are substances which keep fine particles away from each other
to prevent flocculation.
When added to formulations they ensure uniform suspension
and retard sedimentation of particles in spray suspension.
They are added to get uniform concentrations of spray all over
the treated area.
e.g., Gelatin, plant gums, sodium carboxy and methyl celluloses.
Foaming agents: reduce drift
Thickeners: reduce drift by increasing the droplet size
Compatibility agents: aid in combining pesticides.
30. Safeners: A chemical which reduces the phytotoxicity of another
chemical is called safener. Copper sulphate when sprayed alone
on the foliage causes phytotoxicity. Lime is added to copper
sulphate in the preparation of Bordeaux mixture as a safener.
Glyceride oils are also used an safeners.
Deodorants: Deodorants are materials added to fungicides to
mask unpleasant smell. e.g., cedar oil, pine oil, various flower
scents.
Buffers: allow pesticides to be mixed with diluents or pesticides of
different acidity or alkalinity.
31. Formulations
Fungicide with red label - Extremely toxic
yellow label - Moderately toxic
blue label - Slightly toxic
green label - Practically non toxic (desirable one)
Toxicity category Oral toxicity (LD50) Dermal toxicity (LD50)
I (red) – Danger 0-50mg/kg 0-200 mg/kg
II (yellow)-Warning 51-500mg/kg 201-2000 mg/kg
III (blue) – Caution 501-5000 mg/kg 2001-20,000 mg/kg
IV (green) – Caution > 5000mg/kg > 20,000mg/kg
32. Characteristics of an ideal fungicide
• High toxicity to pathogen at low concentration.
• It should not be toxic to plant, man, animal, beneficial
microbes, earthworms, etc.,
• Slow or no loss of toxicity in storage (shelf life)
• It should retain toxicity on dilution
• It should have good spreading quality on host surface
• High toxicity or retention on the host surface
• It should have broad spectrum activity
• It should be compatible with commonly used insecticides
and acaricides without any deleterious effect.
• It should be cheap and available easily in the market
• It should not cause environmental pollution.
• It should be easily transportable
33. Classification of fungicides based on
1. Based on mobility in a plant
2. Based on role in protection
3. Based on breadth of activity
4. Based on mode of action
5. Based on general usage
6. Based on chemical composition
34. 1. Based on mobility in a plant
a. Systemic (penetrants)
A chemical that can able to translocate freely in the plant system
after absorption and can control plant pathogens remote from
the point of application and can be detected or identified is
known as systemic fungicides.
E.g. Carboxin, Carbendazim, Thiophanates.
b. Non-systemic or contact fungicides (protectant)
A chemical that can not translocate in the plant system and is
effective only when it contacts with the pathogen. It remain on
the surface of the plant and effective against fungal infection.
Prophylactic in their behaviour
E.g. Copper, Sulphur and Mercury fungicides.
35. 2. Based on role in protection
a. Preventive
Contact fungicides are suited for preventive or prophylactic
Need repeated application
Protectant
Fungicides which are effective only if applied prior to fungal
infection is called a Protectant E.g. zineb, sulphur
36. b. Curative
Due to ability to penetrate the plants they possess both
preventive and curative
Therapeutant
Fungicide capable of eradicating a fungus after it has caused
infection and thereby curing the plant is called therapeutant.
Systemic in action and affect deep seated infection.
E.g. carboxin, oxycarboxin, benzimidazole, antibiotics.
Eradicant
Eradicant are those which remove pathogenic fungi from an
infection court (area of the host around a propagating unit of a
fungus in which infection could possibly occur) and remain active
for some time on the host.
Eradicate both dormant or active pathogen from the host.
E.g. organomercurials, lime sulphur.
37. 3. Based on breadth of activity
a. Single site fungicides
Single metabolic pathway or single critical enzyme or
protein needed by the fungus are targeted or affected
Highly specific
Systemic property
Development of fungicide resistance is common
b. Multisite fungicides
Older, contact fungicides
Affect in several ways
38. Single site inhibition (systemic compounds)
Inhibits specific enzymes/process
e.g. Benzimidazoles - inhibit cell division by affecting β-tubilin
Azole fungicides - inhibit sterol synthesis found in cell
membrane (Sterol Biosynthesis Inhibitors)
Morpholines - SBI
Phenylamides - Nucleic acid synthesis
Strobilurins - Block mitochondrial electron transport
Multisite inhibition
Affect central metabolic process and affect production of energy /
ATP by inhibit respiration or by oxydative phosphorylation
e.g. Metal based (Cu/Hg) – inhibit wide range of enzymes
involved in metabolic pathways
Dithiocarbamates - inhibit thiol groups or proteins and
inactivate enzymes and cause death of cells.
39. 4. Based on mode of action
Fungicides that kill the fungi by
damaging their cell membrane
inactivating critical enzymes or proteins
interfering energy production/respiration
inhibiting sterol biosynthesis
inhibit chitin biosynthesis
inhibit RNA polymerase (phenyl amides in oomycota)
inhibit nuclear division / cell division (benzimidazoles)
Recent chemicals – activation of SAR (induce resistance in
plants or antifungal proteins or cell wall thickening)
40. 5. Based on general usage
a. Seed protectants
b. Soil fungicides (Pre-plant)
c. Soil fungicides (Applied when plants are in the field)
d. Foliage and blossom protectants
e. Fruit protectants
f. Tree wound dresser
g. Antibiotics
41. 6. Based on chemical composition
Mercurial fungicides – Organic and Inorganic
Copper fungicides
Sulphur fungicides – Inorganic and Organic
Quinones
Heterocyclic nitrogen compounds
Aromatic compounds
Miscellaneous
![Fungicide [Latin word – Fungus + caedo (to kill)] or Fungitoxicant is
a chemical, which has the ability to kill the fungus.
Fungistat is a chemical, which inhibits the fungal growth temporarily.
The phenomenon of temporary inhibition is known as
fungistasis. e.g., Gliodin, Chloroneb
Antisporulant – A chemical, which do not affect the growth of
vegetative hyphae but inhibits the spore production is known as
antisporulant. e.g., Bordeaux mixture](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)