Detailed classification of fungicides, Mode of action, Strobilurins, Banned fungicides

2. Therapy - Groups of Fungicides
Therapy: A treatment or an attempt to cure the disease.
✓The word ‘fungicide’ originated from two latin words,
viz, ‘fungus’ and 'caedo'.
'fungus' means "a mushroom"' and caedo' means 'to
kill'.
Thus the fungicide is any agency/chemical which has
the ability to kill the fungus.
✓ According to this meaning, physical agents like ultra
violet light and heat should also be considered as
fungicides.
✓ However, in common usage, the meaning is
restricted to chemicals only.

3. Characters of an ideal fungicide
1. It should not cause phytotoxicity.
2. It should have long shelf life.
3. Stability during dilution.
4. It should be less toxic to human being, cattle,
earth worms , microorganisms etc.
5. It should be a target specific in its action.
6. It must show compatibility with other
agrochemicals.
7. It must be a cheaper one.
8. It should be available in different
formulations.
9. Easy to transport.

4. Classification of Fungicides.
Fungicides can be broadly grouped based on their (i)
mode of action (ii) general use and (iii) chemical
composition.
I. Based on Mode of Action.
Protectant(Prophylactic):Fungicide which is effective
only if applied prior to fungal infection is called a
protectant, eg., Zineb, Sulphur.
Therapeutant:Fungicide which is capable of
eradicating a fungus after it has caused an
infection,eg:Carboxin, Aureofungin. Usually
chemotherapeutant are systemic in their action.
Eradicant:those which remove pathogenic fungi from
an infection court. eg.Organo-Mercurials, lime
sulphur.

5. II. Based on General Uses.
1. Seed Protectants : Eg. Captan, Thiram,
Carbendazim.
2. Soil Fungicides (preplant) : Eg.Chloropicrin,
Formaldehyde, Vapam.
3. Soil Fungicides(for growing plants) : Eg.
Bordeaux mixture, Copper oxy chloride, PCNB.
4. Foliage and Blossom : Eg. Ferbam, Zineb,
Mancozeb, Chlorothalonil.
5. Fruit Protectants : Eg. Captan, Maneb,
Mancozeb.

6. 6. Eradicants : Eg. Organomercurials, Lime
Sulphur.
7. Tree wound dressers : Eg. Bordeaux paste,
Chaubattia paste. Generally these are applied
to the trees and shrubs after training and
Pruning operation.
8. Antibiotics : Eg. Actidione, Griseofulvin,
Streptomycin, Streptocycline.

7. III. Based on Chemical Composition.
Major group of fungicides used include salts of
toxic metals and organic acids, organic
compounds of sulphur ,quinones and
heterocyclic nitrogenous compounds. Copper,
Mercury, Zinc, Tin and Nickel are some of the
metals used as base for inorganic and organic
fungicides.
✓ Fungicides made up of Non metals like
sulphur, chlorine, phosphorous are also there.
✓ Common Groups of Fungicides – Copper
Fungicides, Sulphur Fungicides and Mercury
Fungicides,Benzene and Systemic Fungicides.

8. Sulphur Fungicides.Contact and Protective in
action.1.Inorganic Sulphur:
•Elemental Sulphur •Lime Sulphur
✓Both are useful to control Powdery Mildew and
Apple scab disease.
2.Organic Sulphur:Dithiocarbamates
i)Monoalkyl:Zineb,Maneb,Mancozeb,Nabam(Alg
ae and leaf spot),Vapam(Effective on Soil Borne
Pathogens and also acts as a Herbicide,
Nematicide).
ii)Dialkyl:Ziram(Anthracnose),Ferbam,Thiram(c
an be used in seed treatment both as dry powder
or as a slurry).

9. Copper Fungicides: First Mentioned by Prevost to
control wheat bunt disease.
✓Bordeaux Mixture:contains 8 lbs of CuSO4 + 8 lbs
of lime + 100 gallons of water. Developed by PMA
Millerdet to control Downy mildew of grapes.
CuSO4 + Ca (OH)2--->Cu(OH)2 + CaSO4.
Cupric hydroxide is the active principle and is toxic
to fungal spores.
✓ Burgundy mixture:In this mixture lime is replaced
by sodium carbonate or washing soda. developed
by Mason.Its a good substitute for bordeaux mixture
and used in copper sensitive crops. it contains 1 kg
of copper sulphate and 1 kg of sodium carbonate in
100 litres of water.

10. ✓Chaubattia Paste: Developed by V.B
Singh.Prepared by mixing 800g of copper
carbonate and 800g of red lead in litre of raw
linseed oil.Act's as a wound dresser.
✓COC: Copper Oxychloride effective against
Oomycetes fungi and has Antibacterial property.
This can be applied as foliar fungicide as well as
soil fungicide .
✓Cuprous hydroxide: Protective fungicide
mainly used in Seed treatment.

11. •Phytotoxicity of Bordeaux is reduced by increasing
the ratio of hydrated lime to copper sulfate.
•For spraying young, actively growing plants, the
amounts of both copper sulfate and hydrated lime are
reduced.
•In “fixed” or “insoluble” copper compounds, the copper
ion is less soluble than that in the Bordeaux mixture.
Therefore, less phytotoxic than Bordeaux but are
effective as fungicides.
ex:CuSO4,Copper oxides.
•Inorganic Sulphur may cause injury in hot
(temperatures above 30°C), dryweather, especially to
sulfur-sensitive plants such as tomato, melons, and
grapes.

12. Mercury Fungicides:
✓Highly fungitoxic,due to their residual toxicity in soil
and plants and their extreme toxicity nature to animal
and human beings, the use of mercury fungicides is
being discouraged.
• In most of the countries, the use of mercury fungicides
is banned and in countries like India, the use of
mercury fungicides is restricted only in seed
treatment for certain crops.
I. Inorganic Mercurial Fungicides:
•Mercuric chloride(treating tubers and propagative
materials of other root crops)
•Mercurous chloride(limited to Soil application
only). Because it causes phytotoxicity.

13. II. Organomercurials.
✓Methoxy ethyl mercury chloride
✓Ethyl Mercury Chloride
✓Phenyl mercury chloride.mainly used for
treatment of seeds and planting materials.
Heterocyclic Nitrogen Compounds.
✓Captan (Kittleson's Killer): used seed
dressing fungicide.
✓Captafol: Protective fungicide.
Benzene compounds.
✓ Quintozene (PCNB): used for seed treatment
and soil application.
✓Dinocap: Contact,Acaricide and Powdery
Mildew fungicide.

14. Organo–Phosphorous.
✓Edifenphos: effective against Rice Blast and Brown
spot. ✓Iprobenfos:Sheath blight of rice.
Organo Tin compounds.
✓Fentin hydroxide and Fentin acetate: to control
foliar diseases.
Systemic Fungicides. Any compound capable of
being freely translocated after penetrating the plant is
called systemic.However, have not been very
successful in the cases of trees and shrubs.
1)Oxathiin:The first systemic fungicide Carboxin was
developed by Von Schmeling and Kulka in
1966.Carboxin effective against smut diseases.Trade
name is Vitavax.

15. (ii) Oxycarboxin:Trade name Plantvax ,used
against rusts.
Benzimidazoles.
✓Benomyl ✓Bavistin- superior fungicides which
acts as a good eradicant and protectant.It is used
as spray, seedling dip, seed treatment, soil
drench and as post harvest treatment of fruits.
Thiophanates: it has thiourea group.
✓Thiophanate ✓Thiophanate Methyl: Broad
Spectrum Fungicides.
Morpholines✓Tridemorph: fungicide with
Systemic and Eradicant action, highly effective
against Powdery mildews.

16. Phenylamides:
✓Metalaxyl: Effective against Oomycetes fungi.
Triazoles: Most active on powdery mildews, rusts and
leaf spot fungi.ex:Tricyclazole(specific fungicide used
against paddy blast fungus) and Propiconazole.
Pyrimidines.
✓Triadimefon ✓Triadimenol: These are useful to
control Powdery Mildews and rusts.
Hydroxy Pyrimidines.
✓Ethirimol ✓Dimethirimol: effective against Powdery
Mildews.
Phenol derivative.
✓Chloroneb: Active against storage diseases of fruits.

17. ✓ Fosetyl Aluminium is a systemic fungicide
effective against Oomycetes fungi which
shows Acropetal movement when applied to
plant surface belongs to Organophosphorus
compound.

18. Strobilurin group of Fungicides
✓This group contains the newest and most important
fungicides. The first such fungicide was isolated from the
wood-rotting mushroom fungi Strobilurus
tenacellus.✓There are now 10 major strobilurin
fungicides on the market, which account for 23-25 % of
the global fungicide sales eg: Azoxystrobin, kresoxim-
methyl, picoxystrobin.
✓Strobilurins are mostly contact fungicides,but some
strobilurins,such as azoxystrobins, move trans-laminarly
and systemically through the vascular system of the
plant. Sometimes it shows growth-promoting effects
also.
✓They have a unique mode of action like they inhibit
electron transfer in mitochondria, disrupting metabolism

19. In-vitro effect of newer fungicides on
mycelial growth in biocontrol fungus
Trichoderma harzianum.
Dinesh1,*, Bisht KS2, Tewari AK2(2016)
Abstract: Trichoderma harzianum (Th 14) was
tested in-vitro for its compatibility with different
concentrations of commonly used newer
fungicides. Six systemic viz.,
Metalaxyl,hexaconazole, tebunaconazole,
difenaconazole, propinconazole, carbendazim
and two contact fungicides mancozeb and
captan were used, each at concentrations of 25,
50 and 100 ppm.

21. Fungicides group According to FRAC.
•Group Name
The Group Names listed are based on chemical
relatedness of structures which are accepted in
literature (e.g. The Pesticide Manual). They are
based on different sources (chemical structure,
site of action ).
Chemical or Biological Group
Grouping is based on chemical considerations.
Nomenclature is according to IUPAC and
Chemical abstract name.
Taxonomic information may be used for agents
of biological origin.

26. Chemical name Trade name.
Copper oxychloride. Blitox-50.
Copper sulphate. Blue copper.
Ethyl mercury chloride. Ceresan
Methoxy ethyl mercuric chloride Aretan
Benlate. Benomyl
Carbendazim. Bavistin
Maneb. Dithane M-22
Mancozeb. DithaneM-45,Indofil
Zineb. Dithane Z-78.
Propineb. Antracol
Tebuconazole. Folicur

27. Thiocarbamate fungicides - Reliable tools in
resistance management and future outlook-
Tarlochan S Thind(2012)
Abstract:
• Among contact fungicides, dithiocarbamates have remained
successful and are used worldwide. Example mancozeb, zineb,
ziram, and propineb which have a multi-site mode of action and broad-
spectrum disease control .
• So it makes them the most common mixture partners with a number of
single-site fungicides as part of resistance management strategies.
Like ethylene-bis-dithiocarbamates such as mancozeb in delaying the
evolution of phenylamide resistance in several oomycete
phytopathogens that laid the groundwork for mixture strategies .
• Dithiocarbamates are only the surface protectants, and have to be
applied prior to pathogen infection. Dithiocarbamates will likely to play
a key role as reliable resistance management tools to prolong the
efficacy of single-site fungicides.

28. ✓These multi-site fungicides are important components of
resistance management strategies because they delay
development of resistance to single-site fungicides in mixtures.
✓ Use as mixture partners and in rotations:Since
dithiocarbamate fungicides are effective against both resistant
and sensitive strains of the pathogen, such mixtures reduces the
rate of evolution of resistance.
✓ Synergy with partner fungicides:A 1:6 ratio of azoxystrobin
and propineb exhibited stronger synergistic action over the chilli
fruit rot causing fungi Phytophthora capsici.
✓Slow release of active ingredients:Using polyethylene glycol
as a “capping agent”, a nanoformulation of mancozeb has been
developed that shows a good control of target pathogens.

31. Resistance Management Strategies.
✓Avoid repetitive use of same fungicide.
. ✓Limit the
number of treatments. ✓Apply
protective sprays early in the epidemic.
✓ Apply recommended dosage only.
✓ Integrate with non-chemical methods.i,e
follow IDM practices.

32. References:
• Thiocarbamate fungicides - Reliable tools in
resistance management and future outlook Tarlochan
S Thind and Derek W HoHollom.
• http://ppqs.gov.in
• http://ecourseonline.iasri.in
• FRAC Code List ©*2020:Fungal control agents sorted
by cross resistance pattern and mode of action.
• An Overview of Strobilurin Fungicide
Degradation:Current Status and Future Perspective
Yanmei Feng, Yaohua Huang, Hui Zhan, Pankaj Bhatt
and Shaohua Chen.