Chemical control of plant disease

CHEMICAL CONTROL OF PLANT DISEASES
DR. RAJBIR SINGH
Assistant Professor
Department of Plant Pathology
Gochar Mahavidyalaya, Rampur Maniharan, Saharanpur (UP), India
Affiliated to Ch. Charan Singh University, Meerut (UP), India
Email: rajbir25805@yahoo.com, rajbirsingh2810@gmail.com
Cell No. 91-9456613374

CHEMICAL CONTROL
1. Protectant chemical
2. Eradicant chemical
3. Chemotherapeutants

Methods of Application
1. Spraying
2. Dusting
3. Fumigation

Merits of Spraying
1. Less cost of active ingredients per unit
2. Good coverage/deposition
3. Residual effect for more
4. Can spray in high wind velocity ( till 10 mile/hr)
5. Drop size can adjust
6. Better utilization of chemical & can reduce drift loss

Demerits of Spraying
1. More time & labour
2. Sprayers are heavy
3. Sprayers are costly
4. Have to prepare before use
5. Storage problem
6. No spraying in moist weather

Seed Treatment
1. Seed disinfectants -
a. internally seed borne
b. Exp. Vitavax, Carbedazim
2. Seed disinfestants
a. externally seed borne
b. Exp. Copper corbonate
3. Seed protectants
a. soil borne pathogen
b. Exp. Thiram, Captan

Methods of Seed Treatment
1. Dry seed dressing/ treatment
2. Slurry treatment
3. Seed dip method
4. Planter hopper box seed treatment

Methods of Soil Treatment
1. Soil drenching
2. Broadcasting of dust, powder or granules
3. Furrow application
4. Spot application
5. Strip application
6. Pits application
7. Plantation site application

Fungicide
Latin word
Fungus + caedo (to kill)
“Fungicide has been defined as a
chemical substance which has the
ability to prevent damage caused by
fungi to growing crops and their
products”

Classification of Fungicides
(A). On the basis of chemical nature
(1). Protectants- Exp - Thiram
Create a barrier b/w plant & pathogen
(2). Eradicants- Exp- Tilt
Remove the pathogen from infection court
(3). Systemic & Non Systemic- Exp. Contaf

(B). Base on the General Use
(1). Seed protectant – Exp. Thiram
(2). Soil Fungicide – Exp. Captan
(3). Foliage & Blossom Protectant – Exp. Ferbam
(4). Fruit Protectant- Exp. Captan
(5). Tree Wound Dressing- Exp. Bordeaux Mixture

(C). Base on the Chemical Nature
(1). Sulphur compounds
(2). Copper Compounds
(3). Mercury Compounds
(4). Quinones
(5). Aromatic Compounds
(6). Heterocyclic Compounds
(7). Organotin Compounds
(8). Benzimidazoles
(9). Oxanthins
(10). Others

Characteristics of Ideal Fungicide
1. High field performance
(i). Inherent fungitoxicity
(ii). Active constituents
(iii). Good coverage
(iv). Initial deposition
(v). Residual effect

(2). Low Phytotoxicity
(3). Stability in Storage
(4). Stability after Dilution to Spray Strength
(5). Low Toxicity to Human beings & Cattles
(6). Cheap & Easily Available
(7). Compatibility
(8). Simple to Prepare & Easy to Apply

Formulations of Fungicides
(1). Wettable Powders or WP
(2). Dust or Dustable Powder or DP- 4-10% AI
(3). Emulsifiable Concentration or EC
(4). Granules or G
(5). Suspension Concentrate or SC
(6). Slurries or Water Dispersible Powder for Slurry
Treatment or WS
(7). Solution

Sulphur Compounds
S compounds
Inorganic Organic
i. Elemental Sulphur i. Ziram
a). Dust sulphur ii. Febam
b). Wettable sulphur iii. Thiram
ii. Lime sulphur iv. Menab
vi. Nebam

Sulphur Dust
• S - dust should be very fine
• Particle size- 200-300 mesh or 47-74 µ
• Natural ‘S’ from ores is grounded & used
• Rate – 25 kg/ha – Rotary duster
• S- control Powdery mildew
• S- dust can be used as ST for sorghum smut

Wettable Sulphur
• Formulated as 80% WP
• T.N.- Thiovit, Cosan, Microsulf, Ultra sulphur
• Rate - 0.2- 0.25%
• Control- P. M. of Veg. & Fruits crops

Lime Sulphur
• Calcium polysulphide = Ca S2
• L. S used as spray – Use only in Fe/Zn pots
Rock lime = 20 lbs
Sulphur = 15 lbs
Water = 50 gallon
• Method – add water into lime & add S slowly &
stir of suspension continue – colour become
golden yellow
• Use supernatant
• Dose- 0.75- 1.0 gallon/ 100 gallon water for
cucurbits, vegs. Pea etc.
• 1.0 – 2.o gallon/ 100 gallon for woody trees
* 1 gallon = 3.78541 Litre

Organic S fungicides
• Derivatives of Dithiocarbamates
(Dithiocarbamic acid)
• Dithiocarbamic acid is methylated to
unstable the fungicidal property
• Zn, Fe, are used to stabilize dimethyl
dthiocarbamate

1. Ziram
• Zincdimethyl dithiocarbamate
• T. N. – Corozate, Hexazir, Zirberk, Zerlate
• Used as spray- @ 0.15-0.25%
• Diseases controlled- E. B. of potato,
Alternaria sp., Colletotrichum sp. Rust etc.

2. Ferbam
• Ferric dimethyldithiocarbamate
• T. N. – Fermate, Hexferb, Ferberk, Coromet
• Dose - @ 0.1 - 0.3% as foliar spray
• Dis. controlled-Fungal diseases of veg & fruits

3. Thiram
• Tetramethyal thirum disulphate
• T. N. – Arasan, Hexathir, TMTD, Thylate, Thiride
• Used as S.T
• Dose - @ 0.2 - 0.3% & as soil fungicide- 10-25 kg/ ha
• Dis. Controlled- Damping off, stem gall of coriander

4. Zineb
• Zinc ethylene bisdithiocarbamate
• T. N. – Indofil Z- 78, Lonacol, Parzate C, Dupont
• Used as foliar spray
• Dose - @ 0.2 - 0.3%
• Dis. controlled- Rust, D.M., Alternaria blight, L.B. of
potato, Anthracanose, cercospora leaf spot

5. Maneb
• Mengnese ethylenbisdithiocarbamate
• Not available in India
• In India- Dithane M-45 (Maneb 78% + Zinc 2%)
• More effective than Zineb
• Dose - @ 0.2 - 0.3% as foliar spray
• Dis. controlled- Anthracanose of tomato, tobacco,
cucurbits, D.M. of pea, rust of pea & wheat

6. Nabam
• Disodium ethylenebisdithiocarbamate
• T. N. – Vapam, Chemvape
• Used as fumigant fungicide
• Dose - @ 1.5 – 2.5 litre for 10 SQM area
• Used for – weed flora, fungi & nematode

Copper Fungicides
1. Copper sulphate preparations
2. Copper carbonate preparations
3. Copper oxychloride preparations
4. Cuprous oxide preparations
5. Oxine copper preparations

1. Bordeaux Mixture
• 1882 – Prof. Millardet
• Bordeaux University France
• D.M of grape–Medoc- till Oct. remain green
• Published – 1885 but used 1887

4 : 4 : 50 = 0.8%
Copper sulphate : Lime : Water
5 : 5 : 50 = 1.0%
6 : 6 : 50 = 1.2%
Mostly used – 4 : 4 : 50 (0.8%)

Objective – Prepare 1% Bordeaux Mixture
Requirements – CuSO4, Lime, Water, Earthen pots,
Muslin cloth, Rod, Potassium feracynide
Method –
i). Dissolve 5 kg CuSO4 in 250 Litre water in earthen/
wooden pot
ii). Dissolve 5 kg lime in 250 Litre water & filter in muslin
cloth
iii). Mixed both mixture in other pot very well by shaking
with rod

Testing for Phytotoxicity:
• Take few amount of mixture in test tube
• Add few drops of potasium feracynide in tubes
• If reddish brown deposit appear than add lime
Precautions :
• Use immediately after preparation – 60 gm sugar in 500 lt. BM
• Never use metallic container for B. M. preparation (Fe/Zn)
• Test the phytotoxicity level before use – leaf burning, russeting
Disease control: D.M., P.M., L.B., Anthracanose, Leaf
spots, citrus canker etc.,

2. Bordeaux Paste
CuSO4 : Lime : Water
450 gm : 450 gm : 4.5 Litre
Uses - ↓ amount of water used as dressing
Exp. Stem Secretion of Coconut

3. Burgundy Mixture or Soda Bordeaux
Mixture
• Mason – 1887
• Burgundy in France
• Sodium Carbonate (Na2CO3) used in
place of lime

i). 5 kg : 6.25 kg : 500 litre
CuSO4 : NaCO3 : Water
ii). 10 kg : 12.5 kg : 500 litre
iii). 4 kg : 5 kg : 500 litre
• Test acidity/alkalinity by litmus paper before use
• If blue litmus – become red – acidic – make neutral
• B. M. not used now a days because lime is available & it
is less effective & costly than B.M.

4. Cheshunt Compound
• Bewley – 1921
• Copper sulphate ( CuSO4. 5 H2O) = 2 parts
• Ammonium carbonate (NH4)2CO3) = 11 parts
• Mix above compounds
• Keep the mixture in a bottle for 24 hrs before use otherwise
Ammonia will be loss
• Add 30 gm mixture in 9 litre water
• Used for- drenching for damping off for disinfection
• Not store in metallic containers

5. Chaubattia Paste
• Developed in Govt. Fruit Research Station Chaubattia
i. Copper carbonate = 800 gm
ii. Red Lead powder = 800 gm
iii. Raw Linseed oil = 1 litre
• Prepare a paste in a earthen/ glass pots by mixing above
• Used as wound dressing
• Exp. – black stem of apple & pear, die back of peach, collor
rot of apple & peach

6. Copper oxychloride compounds
• In India low soluble copper is available in the form of
copper oxychloride
• Copper oxychloride CuCl2.3Cu(OH)2- reacting with air
• 4-12% - copper oxychloride – dust
• 50% copperoxychloride – spraying (WP)
• T. N. – Blitox- 50, Fyttolan, Blue copper 50, Cupramar
• Used – Pernospoirales fungi
• Spraying - @ 3-4 kg/1000 litre water & Dusting - @ 25-35 kg/ha

7. Cuprous oxide
• 4-12% - – dust
• 50% – spraying (WP)
• T. N. – Fungimar, Perenox, Cuprocide, Cuprous- 50
• Used – Blight, D.M., & Rust fungi
• Spraying -@ 3-4 kg/1000 litre water & Dusting - @ 25-35 kg/ha

Dicarboximide Fungicides
1. Iprodione :
• 3-(3, 5-dichlorophenyl)-N-(1-Methyl,2,4-dioxo-1-
imidazolidinecarboximide)
• T. N. – Rovral, Glycophene, Chipco 26019
• Contact fungicide
• 50 WP or Dust
• Used- Botrytis, Sclerotinia, Monilinia, Alternaria,

2. Vinclozolin:
• 3-(3, 5-dichlorophenyl)-5-ethenyl-5- methyl-2,
4-oxazolidinedione
• T. N. – Ronilan, Ornalin, Vorlan
• 50 % WP
• Contact fungicide
• Used- Botritis, Sclerotinia & Monilinia etc.

Mercury Fungicides
Mercury fungicides
Inorganic Organic
1. Mercuric chloride HgCl2 1. Ethyl mercury chloride (EMC)
2. Mercurus chloride Hg2Cl2 2. Phenyl mercury acetate (PMA)
3. Methoxyethyl mercury chloride (MMC)

• Inorganic- HgCl2 was used earlier as ST
but due to high toxicity now not used.
• Organic- use is restricted only for ST
• Are sold in India under the following names

1. Agrosan GN- pink colour- used as ST- Jowar, Maize,
Bajara, Cotton etc. – 1% metallic mercury
1. Agallal- radish colour- 3-6%- wet treatment – S. cane
setts & potato
1. Ceresan - i. ceresan wet
ii. Ceresan dry
1% metalic used as ST.- Maize, Jowar, Bajara etc.
4. Aretan – T. N. Aretan-6, 6% metallic used for ST. of S.
cane & potato

HETROCYCLIC NITROGEN COMPOUNDS
1. Captan-
• N- trichloromethyl-thio-4-cyclohexene-1, 2-dicarboximide
• T. N. – Captan, Esso fungicide 406, Orthocide 406, Vanicide
89
• Used as ST & SLT
• Available as WP 83% in India
• ST - @ 0.2 - 0.3%
• SLT- @ 20 – 25 kg/ha
• Dis. Cont. – Damping off of seedlings caused by Pythium

2. Captafol –
• Cis - N- 1,1,2,2, tetrachloromethylthio - 4- cyclohexane 1-2,
dicarboximide
• T. N. - Difolatan- 80 WP
• Dis. Cont. – Alternaria blight & L. B. of potato
3. Folpet-
• N- trichloromethylthiophthalimide
• T. N. – Folpet, Pholtan, Orthophaltan
• Used as Captan – this also act against P. M.

QUINONE FUNGICIDES
1. Chloronil –
• 2,3,5,6-tetrachloro-1, 4-benzequinone
• T. N. – Spergan
• Used as ST
• Dis. Cont. – Smut & bunts
• @4-8 auns/100 lbs

2. Dichlone-
• 2,3 – dichloro 1,4 –napthoquinone
• T. N. – Phygon, Phygon XL
• Used as ST but as FS in apple scab
• @ 1- 4 auns/100 lbs
• Dis. Cont. - Smuts

BENZENE COMPOUNDS
1. Diazoben –
• Sodium-p-dimethylaminobenzene
diazosulfonate
• T. N. – Dexon
• Used as ST & SLT
• Dis. Cont. – Damping off & root rot

2. Chlorothalonil –
• 2,4,5, 6-tetrachloro-isophthalonitrile
• T. N. – Kavach, Bravo, Termil- 75% WP & 20% dust
• Used as F. S & dusting
• Dis. Cont. – E. B., D. M. Rust, scab etc.
• @ 0.1- 0.2%

3. Dinocap
• Methyl heptyl dinitrophenyl
• T. N. – Karathane, Arathane, Mildex
• Used as FS
• Dis. Cont. – PM

Systemic Fungicide
1966 - Von Schemeling and Kulka
Systemic fungicides on application to
various plant parts absorbed by plant
tissues, Tranlocated upward or downward,
control plant diseases away from place of
application are detectable in plants in its
form or as metabolites.

Advantage
• Control when pathogen already established
• Cover foliage & inflorescence more effectively
• Away from place of application
• More specific inhibitors of biosynthetic process
• Translocated hence used at low con.
• Effectivity of non systemic governed by correct placement
of chemical but not in SF
• Not subject to prolong weathering after spray as in non SF

Movement of Fungicides in Plants
1. Apoplastic trsnslocation
upward movement
by Xylem
2. Symplastic translocation
downward movment
by phloem
3. Ambimobile
up & down both side movement
4. Toxophere
many S.F. are metabolized or degraded inside plants

Benzimidazole Compounds
1. Benomyl
• Methyl -N-(1-butylcarbamoyl)-2 benzimidazole carbamate
• T.N.- Benlate, Tersan 1991, Krimenomyl
• 50% WP
• Used as ST, FS
• Used for- Smut, PM, Scab, Blast etc.

2. Carbendazim
• Methyl-2-benzimidazole carbamate or MBC
• T.N.- Bavistin, Derosal, Bengard, Dhanustein
• More stable than Benomyl
• 50% or 60% WP & 25% Seed dressing powder
• Used as ST & FS
• Used for- PM, scab, dipping of fruits & roots

3. Thiabendazole
• 2, 4 – thiazolyl - benzimidazole or TBZ
• T.N.- TBZ, Mertect, Thiabendazole W-7
• 60% WP
• Used as ST, FS, soil drench, soil mix & fruit dip
• Used for – rotting of fruits as post harvest dip or
spray in apple, pear, banana & citrus

4. Thiophanates
• 1, 2 - bis (3 - ethoxycarbonyl 2- thioureido) benzene
• T.N.- Topsin, Topsin M, Roko, Alert, Cercobin
• 60% or 70% WP
• Used as FS
• Used for- Cercospora leaf spot, PM, Sheath blight, Scab

Oxathins Compounds
1. Carboxin
• 5,6, dihydro-2-methyl-1,4-oxathin, 3 -carboximide
• T.N.- Vitavax, Vitavax 200
• 75% WP, 10% dust
• Used as ST for smut, bunt, R. solani, S. rolfsi
• SLT- 1.5 kg/acre

2. Oxycarboxin
• 5, 6, dihydro – 2 – methyl - 1, 4 - oxathin, 4 - dioxide
• T.N.- Plantvax, Plantvax L
• Not as good as Vitavax, specialy for basidiomycotina
• 75% WP, 10% dust, 5% granules
• ST - 0.1-0.5% - L.S. of wheat, barley, flag smut of wheat,
smut of sorghum, R. solani, S. rolfsi & rust pathogen
• FS - 0.1 - 0.2% - rust pathogen – 2 - 3 sprays

Acylalanines or Acylanilides
1. Metalaxyl
• N-(2-Dimethylphenyl)-N-(methoxyacetyl)-alanine methylester
• T.N.- Ridomil, Apron, Ridomil MZ-72
• Specific to oomycetes – pernosporales
• Used as ST, SLT & FS
• 25% & 50 % WP, granules – 1%, 2% & 5% and 5% EC
• FS- L. B. of potato, DM of pea & cotton
• Ridomil MZ- DM of mustard
•

2. Furalaxyl
• Methyl- N - 2, 6 dimethylphenyl-n-furoyl (2) alaninate
• T.N.- fongarid, fonganil
• 25% & 50% WP, 10% dust
• Specific to Phytium & Phytophthora spp. – for soil
borne diseases

Pyrimidines
1. Dimethirimol
• 5-n-butyl-2-dimethylamino-4-hydroxy-6-methylpyrimidine
• T.N.- Milcurb
• 1.25%, 10% & 12.5% liquid form & 5% granules
• Used for PM of cucurbits & chrysanthimum
• Cucurbits @ 1-4 kg/ha

2. Ethirimol
• 5-n-butyl-2-dimethylamino-4-hydroxy-6-methylpyrimidine
• T.N.- Milstem
• 80% WP & 20% aqueous solution
• Used for PM of cereals (wheat & barley) @ 0.25%

Morpholines
1. Tridemorph
• N-tridecyl-2,5-demethylmorpholine
• T.N.- Calixin
• 75% EC
• Used for PM of various crops
• Effective against PM of various crops but higher dose is phototoxic
• PM of barley, Cucurbits , beetlvine & rust of g.nut

Organophosphates
1. Kitazine
• O,o-diisopropyl-s-benzylthiophosphate
• T.N.- Kitazin P
• Insecticidal properties – leaf & plant hopper
• 48% EC , 17% granules & 2% dust
• Used for brown spot of maize, leaf blight of onion,
verticillum wilt of egg plant & blast of rice

Alkyl Phosphates
1. Fosetyl- AL
• Aluminium tris-o-ethyl-phosphonate
• T.N.- Aliette, EPAL
• 80% WP & 10% granules
• Translocated both upward & downward
• Toxic to honey bees, fish & birds
• Effective to oomycetes- Pythium, Phytophthora, DM

Piperazine
1. Propiconazole
• 1-(2- (2, 4-dichlorophenyl) - 4propyl-1,3 - dioxolan - 2-
ylmethyl) 1H-1, 2, 4 - trizole
• T.N.- Tilt 3.6 E & Tilt 250 E
• Effective against- karnal bunt, rust, sheath blight of
rice, PM of grape

2. Tricyclazole
• 5 – methyl - 1, 2, 4 - trizole (3, 4 - b) benzothiazole
• Beam, Blaside
• 20% & 75% WP, 1% dust & 4% granules
• Used as soil drench & FS
• Effective against- blast of rice

Antibiotics
Alexander Flaming – 1929
Penicillin from Penicillum notatum
“A chemical compound produced by one
microorganism that is able to kill or inhibit
the growth of other microorganisms”

Properties of Antibiotics
1. Effective in small amount
2. Specific
3. Mostly antibacterial but also antifungal
4. Systemic in action
5. May be Tem. Sensitive or not be

Mode of Action
1. Direct action on plant surface
2. Direct action inside plant tissues
3. Action after transformation within the plant
4. Action direct on host

Antibiotic Production
(A). Antibiotics derived from amino acids
1. Penicillin - Pencillium notatum
2. Chloromietin – Streptomyces venezuelae
3. Bacitracin – Bacillus licheniformis & B. subtilis
4. Viomycin – S. puniceus & S. floridae

B. Antibiotic derived from sugars
1. Streptomycin- S. griseus
2. Neomycin- S. fradiae
3. Gentamicin- S. spp.
4. Paranomycin – S. rimosus

C. Antibiotics derived from Acetate
1. Tetracycline – S. spp.
2. Puromycin – S. alboniger
3. Griseofulvin – P. griseofulvum
4. Fumagillin – Aspergillus fumigatus

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