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1. INDIRA GANDHI KRISHI VISHWAVIDYALAYA
COLLEGE OF AGRICULTURE, RAIPUR
Department of Agronomy
COURSE TITLE :- AGRON 503 – WEED MANAGEMENT
(2+1)
ASSIGNMENT ON :- Methods of Weed Management
PRESENTEDTO :-
Dr. N. K. Choubey,
Professor,
Department of Agronomy,
College of agriculture , Raipur.
PRESENTEDBY :-
Sonali Chouhan
M.Sc(Ag) Agronomy
College of Agriculture,Raipur

2. Introduction
01
Concept of weed
management
Evolution of weed
management
02
03
Methods of weed
management
04
Reference
05

3. Introduction
Weed : -
- The term Weed was firstly used by Jethrotull.
- weeds are the plants, which self grow where they are not wanted.
- weeds are unwanted or undesirable plants compete with crops for
water, soil nutrients, light and space and thus reduce crop yield.
Losses of agriculture :-
The total annual loss of agricultural produce
1) Weeds - 45 %
2) Insects - 30 %
3) Diseases - 20 %
4) Other pests (Rats, birds & wild animals) - 5 %

4. Concept of weed management
Prevention Eradication Control

5. Prevention
- Prevent entry of weeds into uninfected area.
- Avoid using crop that are infested with weed seeds.
- Clean the farm machinery.
- Avoid the use of gravel sand and soil from weed-infested.
- Keep irrigation channels, fence-lines, and un-cropped areas
clean.
- Quarantine regulations are available in almost all countries to
deny the entry of weed seeds.

6. Eradication
- complete elimination or removal of all live weeds/wild
plants/plants including their seeds and vegetative propagules
from certain area.
- weed eradication is justified against weeds like Striga, Cuscuta
and Lantana.
- Weed eradication programme should begin when the weed
growth is limited.
- If the weed occupied large and continuous areas eradication is
not economical. It should be carried out more than one year.

7. Control
- This includes procedures that reduce but not necessarily eliminate
weed infestations.
- In control methods, weeds are rarely killed but their growth is
severely restricted, the crop gives normal yield.
- management is a part of weed control.
- weed control is done above threshold level.
- chemical methods mainly used among all the control methods.

8. Evolution of weed
management
There are 6 stages in the evolution of weed management
1) 10,000 BC - Removed by hand
2) 6000 BC - Weeds removed by primitive hand tools
3) 1000 BC - Weeding done with the help of animal drawn implements
4) 1920 AD - Machine drawn implements were used for Weeding
5) 1930 AD - Weeding was taken up by biological agents
6) 1947 AD - Weeding by chemical methods ( organic herbicide)

9. Methods of weed management
Preventive Physical Cultural Biological Chemical Biochemical IWM
Mechanical
Manual

10. Preventive Methods
- pure and clean crop seeds.
- well decomposed FYM
- Clean farm machinery and farm animals
- clean irrigation channel & water
- clean farm bunds, roadside, fences and non cropped area
- Transfer of sand and soil
- weed control in the nursery
- plant Quarantine

11. Physical Methods
These are two types.
1) manual method
2) machanical method
1) Manual method :-
Hand Weeding - Removal of weeds either
manually or by using tools like khurpi or sickle.
Effective against annuals and biennials and controls
only upper portion of the perennial.

12. 2 ) Mechanical method :-
* Hand Hoeing -Taking out the weeds with
the help of hand hoes.This is mainly use in
row plantation.Annuals and biennials can
be effectively controlled.
* Sickling - sickle use for remove of the top
growth of weeds to prevent seed
production. Mainly use in irrigation
channel, draging channel, undulating
topography and non cropped area.

13. * Digging :- it is useful for patch and spot weeds.
Digging is very useful in the case of perennial
weeds to remove the underground propagating
parts of weeds from the deeper layer of the soil.
* Mowing :- It is cutting of uniform growth from
the entire area up to the ground level. It is useful
more in non cropped areas than cropped areas.
Effective against erect and herbaceous weeds
* Dredging :- This is used to control aquatic
weeds growing in shallow ditches. Mechanical
pulling of aquatic weeds along with their roots &
rhizomes from the mud.

14. * Burning :- It is cheapest method to eliminate
the mature unwanted vegetation in non-
cropped areas and range lands. Coagulation
of protoplasm occurs with which plant dies
* Flaming :- It is the momentary exposure of
green weeds to as high as 1000°C from flame
throwers to control in row weeds. In flame.
thrower use propane and butane Gas. Mainly
use in row crop and fruit orchard.

15. * Soil solarization:- It is also called solar soil
henting. It is effective against weeds which are
produced from seeds. It doesn't involve any tillage
of the field. Covering the soil with transparent, very
thin plastic sheets of 20-25 mm polyethylene film
during hottest part of summer months for 2-4
weeks.
* Mulching :- Principle is exclusion of sunlight
from environment. Polythene Sheets, natural
materials like paddy husk, ground nut shells, saw
dust etc. are used as mulching material.

16. * Flooding :- Flood kills weeds by excluding
oxygen from their environment.
Merits of physical Method :-
- Oldest, effective and economical method.
- Large area can be covered in shorter time.
- Safe method for environment.
- Does not involve any skill
Demerits of physical Method :-
- Labour consuming
- Possibility of damaging crop
- Requires ideal and optimum specific condition

17. Cultural methods
• Crop Rotation :-
Crop rotation involves alternating
different crops in a systematic sequence on the
same land.
* Cover Crops :- Rapid development and dense
ground covering by the crop suppress weeds. The
inclusion of cover crops such as groundnut, lobia,
Urd in the cropping system can suppress weed
growth.

18. * Time of sowing :- Time of sowing of crops influences
weed competition. If initial big flush of weeds germinating
at one point of time is bypassed through manipulation of the
time of sowing of a crop, a little earlier or later than its
normal time of sowing, the crop may germinate and have
initial growth under almost weed-free or less weedy
environment.
* Crop Density :- Many researchers have demonstrated
that increasing crop density decreases weed competition,
though this strategy poses several risks. Lodging and
disease may increase in certain crops as crop density
increases.

19. * Scheduling of irrigation :-Effective water management
is key to controlling weeds in crop production. In drip
irrigation water is applied in crop root zone and hence weed
growth are minimum.
* Fertilization :- Use of fertilizer can affect the competition
between crops and weeds and in the subsequent crops.
quality of fertilizer , time of application, method of application ,
and rate of fertilizer affects weed population in crop fields.
Broadcasting favours to weed than crops.
* Stale Seedbed Preparation :- This weed management
strategy consists of preparing a fine seedbed, allowing
weeds to germinate and directly removing weed
seedlings via light cultivation.

20. Merits of Cultural Method :-
- Low cost for weed control
- Easy to adopt
- No residual Problem
- Technical skill is not involved
- No damage to crops
- Crop-weed ecosystem is maintained
Demerits of Cultural Method :-
- Immediate and quick weed control is not possible
- Weeds are kept under suppressed condition
- Perennial and problematic weeds cannot be controlled

21. Biological methods
- The use of living organism's viz., insects, disease organisms,
herbivorous fish, snails or even competitive plants for the control
of weeds is called biological control.
- Basic strategies:- Classical, Inductive and inoculative.
- In biological control method, it is not possible to eradicate weeds
but weed population can be reduced.
- This method is not useful to control all types of weeds. Introduced
weeds are best targets for biological control.

22. Qualities of bio agent :-
- The bio-agent must feed or affect only one host and not other
useful plants.
- it must be free of predators or parasites.
- It must readily adapt to environmental conditions.
- The bio-agent must be capable of seeking out itself to the host.
- It must be able to kill the weed or at least prevent its reproduction
in some direct or indirect way.

23. Weed Bio agent Kind of bio
agent
Chondrilla juncea Puccina chondrillina Plant pathogen
Cirsium arvense Septoria cirsii Plant pathogen
Cyperus rotundus Bactra verutana Shoot boring moth
Eupatorium riparium Entyloma
compositarum
Plant pathogen
Hydrilla verticillata Hydrellia pakistanae Shoot fly
Orobanche cernua Sclerotinia spp. Plant pathogen
Parthenium
hysterophorus
Zygogramma
bicolorata
Leaf eating beetle
Weeds and their bio agents

24. Biochemical methods
Allelopathy :- The competitive interaction between the crop species in
intercropping and sequential cropping through the release of chemical
substances or toxins is called Allelopathy.
Bio Herbicide :- Bioherbicides are pathogens cultured artificially and
made available in sprayable formulations; just like a chemical herbicide.
The pathogen selected for the purpose is usually from the native place of
the weed, but it could also be from other places.

25. Bio Herbicide Pathogen Target weed
Devine Phytophthora
palmivora
Morrenia odorata
Collego Colletotrichum
gloeosporoides
Aeschyomone
virginica
Bipolaris Bipolaris sorghicola Sorghum halepense
Biolophosz Steptomyces
hygroscopicus
Non specific
Bio Herbicide and Target weeds

26. Merits :-
- Least harm to the environment
- No residual effects
- Relatively cheaper and comparatively long-lasting effect
- Will not affect non-targeted plants and safer in usage
Demerits :-
- Multiplication is costlier
- Control is very slow
- Success of control is very limited
- Very few hosts specific bio-agents are available at present

27. Chemical methods
Chemical weed control refers to any technique that involves the
application of a chemical (herbicide) to weeds or soil to control the
germination or growth of the weed species.
Herbicide:- Chemicals that are used to kill weeds are called
herbicides.
Types of herbicide :-
1) Classification based on methods of application of herbicides :-
A ) Soil-Active Herbicide :- A soil-active herbicide is one that is applied
primarily to the soil rather than to the vegetation.

28. B) Foliage-Active Herbicides :- A Foliage-active herbicide is
applied to weeds after their emergence from the soil.
2) classification based on time of application of herbicides :-
A) pre plant treatment :- An herbicide treatment made any time
before the crop is planted is called a preplant treatment.
B) Pre emergence treatment :- Application of herbicides soon
after planting of a crop is called pre-emergence treatment.
C) Post emergence treatment :- Post emergence treatment is
the application of herbicide after the emergence of both the
crops and the weeds.

29. 3) Based on spectrum of weed control :-
A) Narrow spectrum herbicides :- control a particular
group of weeds.
B) Broad-spectrum herbicide :- control a wider array of
weeds.
4) Based on selectivity :-
A) Selective herbicide :- The herbicide which kills selectivity
a particular species or group of plants (weeds) in mixed
population of plants (crop and weeds) is called a selective
one.
B) Non-selective herbicide :- The herbicide which kills
indiscriminately any species or group of plants
irrespective of weeds and crops.

30. Types of herbicide Examples
Soil-Active Herbicide simazine, alachlor,
trifluralin, and EPTC etc.
Foliage-Active Herbicides 2,4,5-T, paraquat, diquat,
MCPB, amitrole etc.
pre plant treatment Fluchloralin, Pendimethalin,
Trichloralin and Alachlor
Pre emergence treatment Benthiocarb, atrazine in
maize, diuron in cotton ,
pendimethalin, butachlor
etc.
Post emergence treatment 2, 4-D, Isoproturon,
fluazifop-p-butyle,
fenoxaprop-p-ethyl, clodina
Types of herbicide and their
examples

31. Narrow spectrum herbicides metsulfuron methyl, bentazone,
lactofen, and diclofop methyl,
fenoxaprop-p- ethyl, clodinafop-
propargyl
Broad-spectrum herbicide Metribuzin, Isoproturon,
chlorsulfuron, Alachlor,
butachlor, metochlor,
pretilachlor, Sulfosulfuron,
clamazone, imazethapyr etc.
Selective herbicide Atrazine, pendimethalin, 2, 4- D,
butachlor, lactofen
mesopleuron-methyl
Non-selective herbicide Paraqaut, diquat, glyphosate,
glufosinate, acrolein, piclroram ,
amitrol etc.

32. Merits of chemical method :-
- Herbicides can be applied for weed control in crop rows and
where cultivation is impossible.
- Cultivation & manual methods of weed control may injure the root
system of crops.
- Herbicides can control many perennial weed which cannot be
controlled by other methods.
Demerits of chemical method :-
- Some herbicides are non-biodegradable and are harmful for a long period of
time.
- They are all slightly toxic.
- Some can cause eye and skin problems and upper respiratory effects in the
user.

33. Integrated weed
management
- An integrated weed management may be defined as the
combination of two or more weed-control methods at low input
levels to reduce weed competition in a given cropping system
below the economical threshold level.
- Integrated Weed Management (IWM) approach aims at minimizing
the residue problem in plant, soil, air and water.
- An IWM involves the utilization of a combination of mechanical,
chemical and cultural practices of weed management in a planned
sequence, so designed as not to affect the ecosystem.

34. Why IWM :-
- One method of weed control may be effective and economical in
one situation, and it may not be so in another situation.
- No single herbicide is effective in controlling wide range of weed
flora.
- Continuous use of the same herbicide creates resistance in
escaped weed flora or causes shift in the flora.
- Continuous use of only one practice may result in some
undesirable effects.
- Only one method of weed control may lead to increase in
population of particular weed.
- Indiscriminate herbicide use and its effects on the environment
and human health.

35. Advantages of IWM :-
- It shifts the crop-weed competition in favour of crop.
- Prevents weed shift towards perennial nature Prevents
resistance in weeds to herbicides.
- No danger of herbicide residue in soil or plant.
- No environmental pollution.
- Gives higher net return.
- Suitable for high cropping intensity

36. Reference
- T.K Das ( Page No. - 198- 284 )
- Agri Coaching Chandigarh - Page No. ( 178 – 186 )
- ANGRAU notes - Page No. ( 135 - 149 )

37. Reporter: XX
THANK YOU