Chemical control in Integrated Disease Management

1. CHEMICAL CONTROL IN
INTEGRATED DISEASE
MANAGEMENT
PRESENTED BY
- DIVYA SRIVASTAVA
- 20230AGC018

2. Integrated Disease Management (IDM):
• The Integrated Disease Management (IDM) involves the
need based use of pesticide only when the disease
incidence reach economic threshold levels and this will
promote the build up of many bio-control agent in the
crop ecosystems.
• Thus IDM, a greener alternative to the conventional use of
chemicals, is an attempt to promote natural, economic
and sociological farming methods through the most
effective combination of farming techniques and judicious
and limited use of fungicide.
• In other words, IDM programme implies all the
available disease management approaches including
cultural, biological and chemical control with the main
objective to keep the disease incidence below economic
threshold level.

4. Chemical Control Methods
Chemicals used for controlling insect pests, diseases and weeds are known as
pesticides; and those used for controlling fungal diseases are called fungicides,
those used against viruses are called viricides.
 One of the important or common mean of controlling the plant diseases is
through chemical compounds which are toxic to the pathogens.
 These chemicals inhibit the germination, growth and multiplication of the
pathogen or are lethal to the pathogen.
Classification of Chemical Pesticides: Depending upon the pathogens they
affect, they may be classified as fungicides, bactericides, nematicides,
viricides etc.
 Out of these, some chemicals are broad-spectrum and they are toxic to all
pathogens.
 Most of the chemicals used in plant protection are foliar and are used as
aboveground parts of the plants.
 Some of them are soil disinfectants, and some are used as protectants for
seed, tubers and culms etc. There are some of the chemicals which have
been used prior to disease spread.
 A few chemicals are aimed to eradicate the general inoculum before it
comes in contact with the plant hosts. They are called eradicants or
chemotherapeutants.

5. Spraying and dusting
Soil treatment
Methods of Applications of Fungicides
 Vegetables, ornamentals and trees are attacked by many pathogens which
are present in the soil, like Fusarium and Verticillium and some
bacteria.
 Different chemicals are used as soil drench, dust or granules inside the
soil at the time of planting of the nursery or seedlings to control damping
off, seedling blight, crown and root rot and many other soil borne
diseases.
 Different chemicals particularly fungicides are sprayed either as
protective, curative or post-symptom treatments.
 These chemicals provide a continuous covering on the vulnerable plant
surfaces and do not allow the plant pathogens particularly fungi to invade
them.
 Fungicides generally used as sprays are mancozeb, carbendazim,
dodine, etc.
 Fungicides such as captan, metalaxyl, PCNB and chloroneb, etc. can
be used as soil treatment to overcome above diseases.
Fumigation
• Fumigants like formalin, chloropicrin, methyl-bromide, dazomet and
metham sodium are now being used as fumigants in plant protection
programmes.
 These chemicals are used as volatile or in gaseous form in the soil and are
useful against various groups of organisms like nematodes, insects, fungi
certain bacteria and weeds.

6. Seed treatment
 Stored products are the carrier of inoculum of many pathogens for the
next season. These materials should be first treated with such chemicals
before they are used for next planting season.
 The storage areas like rooms and the walls should also be bleached or
treated with copper sulphate solution or some other sanitizing agents.
 Seeds, tubers, bulbs and roots are usually treated with chemicals to
prevent the pre- and post-emergence damping off of the young seedlings.
Disinfection of warehouses
 The fungicides used for seed treatment are chloroneb, captan, maneb,
mancozeb, PCNB carboxin, benomyl, thiabendazole and triadimenol.
 They are applied directly on seed as dust or as thick water suspension
mixed with the seed or tossed soaking with the chemical solution which is
allowed to dry thereafter.
Tree wound treatment
 The exposed portion of the plant is first sterilized by swabbing it with
antiseptic solution of either sodium hypochlorite or ethyl alcohol.
 Finally, the entire wounded portion is painted with permanent tree wound
dressing such as lanolin paste, Chaubattia paste or Bordeaux paste/
paint.
Post harvest treatment
 Most fungicides here are used as dilute solutions into which the fruits or
vegetables are dipped before storage or as solution used for the washing
of fruits and vegetables immediately after harvesting.
 Among the compounds used for commercial control of post harvest
diseases of fruits are borax, biphenyl, sodium o-phenylphanate and
widely used fungicides benomyl, thiabendazole and imazalil.

8. Copper compounds:
control
Inorganic chemicals
1) Copper compound
2) Inorganic sulphur
3) Carbonate compounds
4) Phosphate and phosphonatecompounds
Types of chemical compounds used for plant disease
 The Bordeaux mixture (copper sulphate + calcium hydroxide), is a
widely used fungicide to control many diseases like bacterial leaf spot,
blights, anthracnose, downy mildews and cankers throughout the
world.
 Copper oxychloride (Brand names: Blitox 50, Blue copper, Fytolan,
etc.) is used to control diseases caused by oomycetes and cankers of
fruit trees.
Inorganic sulphur:
 Elemental sulphur is known as the oldest fungicide. It primarily controls
powdery mildews, certain rusts, leaf blights and fruit rots.
Carbonate compounds:
 Sodium bicarbonate, as well as bicarbonate salts of ammonium,
potassium and lithium are used as fungicides.
 These compounds plus 1 per cent superfine oil are inhibitory and
fungicidal to the powdery mildew fungi on roses, grey mould and
southern blight fungus.
Phosphate and phosphonate compounds:
 Spraying cucurbits or grapevines with either of monopotassium or
dipotassium phosphate gives satisfactory control of powdery mildew
diseases of these two hosts.

9. Aromatic compounds
Organic Chemicals
1) Organic sulphur compounds or Dithiocarbamates
2) Quinones
3) Aromatic compounds
4) Heterocyclic nitrogenous compounds
Organic sulphur compounds or Dithiocarbamates:
• This group includes thiram, ziram, ferbam, nabam, maneb, mancozeb
and zineb.
 They are the derivatives of dithiocarbamic acid which are toxic to fungi
due to isothiocynate radicals and inactivate the sulphydral (SH) group
in amino acids and enzymes within the fungus cells.
 Quinones occur naturally in many plants and are used as fungicides.
 Only two quinone compounds chloranil and dichlone are used.
Quinones
 Penta-chloro-nitro benzene (PCNB) sold as Brassicol controls various
soil borne diseases of vegetables and ornamentals and is applied as dip or
furrow treatment.
 Another fungicide dichloran (DCNA) sold as Botran is widely used
against diseases caused by Botrytis, Sclerotinia and Rhizopus.
 Chlorothalonil is used against many leaf spots, blights, downy
mildews, rusts, anthracnose, scab and fruit rots of fruits and
vegetables.
 Biphenyl is used against various diseases caused by Penicillium,
Diplodia, Botrytis and Phomopsis in case of citrus.

10. Heterocyclic nitrogenous compounds
Systemic Fungicides
 This group includes important fungicides, like captan, captafol and
folpet.
 Captan is excellent fungicide for control of leaf spots, blights and rots
of many fruits and vegetables and is used as seed treatment and foliar
spray.
Acylalanines
Benzimidazoles
Oxanthiins
Organophosphates
Pyrimidines
Triazoles
Strobilurins