3. Weed problems
4.Future outlooks in development of weed science.
5. Why integrated weed management
6.Concept and advantages of weed management
7.Principles of IWM
8. Method of weed management
9.Components of IWM
• Integrated method is a system which brings all feasible
methods of weed control harmonizing them into a single and
co-ordinated system designed to maintain weeds below those
levels at which they cause economic loss.
• Integrated weed management (IWM) is the control of weeds
through a long-term management approach.
• Integrated Weed Management (IWM) approach aims at
minimizing the residue problem in plant, soil, air and water.
1.A weed is a plant growing where it is not desired.
2.Farmer Jethro Tull was the First person who have defined weed
3.Any plant not sown in the field by the farmer is out of place and
is called weed.
4.Any plant or vegetation excluding fungi interfering with the
objectives or requirement of people is called weed.
Recent estimate shows that weeds cause annual loss of Rs. 1980
crores to Indian Agricultural which is more than combined loss
caused by insects ,pests and diseases.
Total annual loss in agricultural produce due to
weed Insect Diseases other pests
FUTURE OUTLOOKS IN DEVELOPMENT OF
1.Assessment of on-farm losses caused by weeds
3. Inter-disciplinary efforts
4. Integrated weed management approaches
5. Extension activity on proper herbicide use
6. On-farm assessment of available IWM options
7.Knowledge-based decision making tools
WHY INTEGRATED WEED MANAGEMENT
The continuous use of the same method leads to the build up
of tolerant weeds.Therefore the suitable combination of
different weed control methods or integrated weed
management (system approach) should be practiced for
minimizing the losses caused by various weeds.
Herbicides have become one of the most important
component in weed control because of use of high yielding
varieties which created economic incentive for farmer to
Concept of (IWM)
Uses a variety of technologies in a single weed management
with the objective to produce optimum crop yield at a
minimum cost taking into consideration economic and socio-
economic constrains under a given agro ecosystem.
ADVANTAGES OF IWM
1. It shifts the crop-weed competition in favour of crop
2. Prevents weed shift towards perennial nature
3. Prevents resistance in weeds to herbicides
4. No danger of herbicide residue in soil or plant
5. No environmental pollution
6. Gives higher net return
7. Suitable for high cropping intensity
PRINCIPLES OF INTEGRATED WEED
1. IWM place the crop in competitive advantage over the weeds
by manipulating the crop habitat by utilizing some biological
differences between crops and weeds.
2. In IWM measures should be directed to reduce the survival
mechanism of weeds in the soil.
3. Crop cultural practices should be incorporated to discourage
the establishment of the perennial and parasitic weeds.
4. Any individual element of the weed management should be
friendly and it should not be harmful to the environment.
5. IWM Practices should be flexible according to the need.
METHODS OF WEED MANAGEMENT
For designing any weed control programme in an area one
must know the nature and habitat of the weeds in that area,
how they react to each environmental changes and how they
respond to herbicides.
MANAGING WEEDS IN THREE DIFFERENT WAYS:
Weeds are removed and collected from crop fields by hand.
The collected weeds are piled on bunds or in case of certain
weeds, taken home to feed animals.
Provides clean and thorough weeding.
Good for resource-poor farmers where labor is available at
MECHANICAL WEED CONTROL
Mechanical or physical methods of weed control are being
employed ever since man began to grow crops.
Tillage removes weeds from the soil resulting in their death.
Hoe has been the most appropriate and widely used
weeding tool for centuries.
3. Hand weeding:
It is done by physical removal or pulling out of weeds by
hand or removal by implements called khurpi, which
Digging is very useful in the case of perennial weeds to remove the
underground propagating parts of weeds from the deeper layer of
5. Sickling and mowing:
Sickling is also done by hand with the help of sickle to remove the
top growth of weeds. Mowing is a machine-operated practice mostly
done on roadsides and in lawns.
Burning or fire is often an economical and practical means of
In this method, the soil temperature is further raised by 5-10 ºC by
covering a pre-soaked fallow field with thin transparent plastic sheet.
8. Stale seedbed:
This is achieved by soaking a well prepared with either irrigation or
rain and allowing the weeds to germinate.
9. Blind tillage:
The tillage of the soil after sowing a crop before the crop plants
emerge is known as blind tillage.
CULTURAL WEED CONTROL
Crops having higher plant density,fast growth and canopy
coverage are used which can compete with weeds.
2. Summer tillage:
The practice of summer tillage or off-season tillage is one of the
effective cultural methods to check the growth of perennial weed
population in crop cultivation.
3. Maintenance of optimum plant population:
Lack of adequate plant population is prone to heavy weed
infestation, which becomes difficult to control later.
4. Stale seed bed:
Initial 1-2 flushes of weeds are destroyed by harrowing before
planting or sowing of the crop.
5. Crop rotation:
The possibility of a certain weed species or group of species
occurring is greater if the same crop is grown year after year.
6. Growing of intercrops:
Inter cropping suppresses weeds better than sole cropping and
thus provides an opportunity to utilize crops themselves as tools
of weed management.
Mulch is a protective covering of material maintained on soil
Chemicals that are used to kill plants or weeds are called
herbicides. Their use has been increasing rapidly since 1944 when
2,4-D was first use as herbicide. In many instance, they offer most
practical, effective and economic means for controlling weeds.
2,4-D Atrazine Pendimethalin
BIOLOGICAL METHOD OF WEED CONTROL
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.
1. Insects : Zygogramma bicolorata - Congress grass
2. Mites : prickly pear
3. Fish : common carp - Aquatic weeds
THERE IS TWO APPROACHES IN BIOLOGICAL
1. Classical biological control approach.
2. Bio-herbicide philosophy approach.
Objective of classical biological weed control is restoring
balance between target alien weed and its natural enemies in
the ecosystem by introduction of suitable, exotic bio-agent.
Bioherbicide approach Involves spray of specific fungal spores
or its fermentation products , against the target weed. These
preparations are called mycoherbicides (Bioherbicides).Eg-
ADVANTAGES OF IWM OVER CONVENTIONAL
WEED MANAGEMENT PRACTICES
1. Viable weed control based upon determined economic injury
levels rather than eradication.
2. Curbing overreliance on Pesticides through the application of
agro ecological knowledge in the integrated use of a suite of
cultural, Physical, biological and information management
3.Minimized negative social and environmental impacts.
CHALLENGES FACED BY IWM IN PRESENT
1.Emergence of feral crops
3.Effect of climate change
4.Evidence of weed developing
5.Production of higher yields while conserving environment.