4. integrated weed management methods A Lecture by Allah Dad Khan

2. WEED MANAGEMENT
METHODS AND
INTEGRATED WEED
MANAGEMENT

3. • The sustainable use of all available methods to reduce
weed pressure without reducing farm income and
damaging the environment.
• Integration of effective and environmentally safe weed
control methods.

4.  • The main emphasis is on herbicides.
 • There have been many concerns with regard to
 environmental, economic and social impacts of
 agriculture and its sustainability.
 • The reduction of pesticide use has become an
important
 objective in both agricultural policy making and
research.

5.  With the IWM approach each practice (e.g.,
 herbicides) supplement other practices rather than
 serve as the sole tactic for weed control serve as the
sole tactic for weed control.
 • The main emphasis is on:
 • Prevention
 • Enhancing crop competition
 • Reducing weed density

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Weed management is an important component of plant protection
improving the production potential of crops.
Methods of Weed Control
For designing any weed control programme in a given area, one must
know the nature & habitat of the weeds in that area, how they react to
environmental changes & how they respond to herbicides.
Principles of weed control are;
 Prevention
 Eradication
 Control
 Management

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Preventive weed control
It is a long term planning so that the weeds could be controlled or
managed more effectively and economically than is possible where these
are allowed to disperse freely.
Following preventive control measures are suggested for adoption
wherever possible & practicable.
1. Avoid using crop that are infested with weed seeds for sowing
2. Avoid feeding screenings and other material containing weed
seeds to the farm animals.
3. Avoid adding weeds to the manure pits.
4. Clean the farm machinery thoroughly before moving it from one
field to another. This is particularly important for seed drills
5. Avoid the use of gravel sand and soil from weed-infested
Cont…

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6. Inspect nursery stock for the presence of weed seedlings, tubers,
rhizomes, etc.
7. Keep irrigation channels, fence-lines, and un-cropped areas
clean
8.Use vigilance. Inspect your farm frequently for any strange
looking weed seedlings. Destroy such patches of a new weed by
digging deep and burning the weed along with its roots. Sterilize
the spot with suitable chemical
9. Quarantine regulations are available in almost all countries to
deny the entry of weed seeds and other propagules into a
country through airports and shipyards.

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Weed free crop seeds
Separating crop seeds from admixture of crop & weed seeds using
physical differences like size, shape, colour, weight / texture &
electrical properties
b. Eradication: (ideal weed control rarely achieved)
It infers that a given weed species, its seed & vegetative part has been
killed or completely removed from a given area & that weed will not
reappear unless reintroduced to the area.
c. Control
In control methods, the weeds are seldom killed but their growth is
severely restricted, the crop makes a normal yield.

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d. Weed management
Weed control aims at only putting down the weeds present by some
kind of physical or chemical means while weed management is a
system approach whereby whole land use planning is done in advance
to minimize the very invasion of weeds in aggressive forms and give
crop plants a strongly competitive advantage over the weeds.
Weed control methods are grouped into cultural, physical, chemical
and biological.
Every method of weed control has its own advantages and
disadvantages.
No single method is successful under all weed situations. Many a time,
a combination of these methods gives effective and economic control
than a single method.

12. Precision Agriculture
An agricultural practice based on in-field
variability.
• It requires the use of new technologies such as It requires the
use of new technologies, such as
global positioning, sensors and information
management tools to assess and understand
variations.
• Estimate pesticides and fertilizers needs in
different locations of the farms different locations of the
farms.
• Maximize profits and reduce negative
environmental impacts by placing herbicides and
fertilizer where it needed

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 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.
 It has proved to be a valuable concept in a few cases, though much is
still to be done to extend it to the small farmers’ 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.
 The nature and intensity of the species to be controlled, the
sequence of crops that are raised in the rotation, the standard of
crop husbandry, and the ready and timely availability of any method
and the economics of different weed-management techniques are
some of the potent considerations that determine the success for the
exploitation of the IWM approach.

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Concept
 Uses a variety of technologies in a single weed management with the
objective to produce optimum crop yield at a minimum cost taking in
to consideration ecological and socio-economic constraints under a
given agro-ecosystem.
 A system in which two or more methods are used to control a weed.
These methods may include cultural practices, natural enemies and
selective herbicides.
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