weed and its control

AGRICULTURE
GROUP NO : 8
 Muniba Tariq
 Nimra Sattar
 Quratulain
 Irfan Tariq
 Hamza Ashraf
 M . Akhtar
 Hussain Mustafa
 Dawood Aslam
 M. Ali
 M. Ahmed

3 2/10/2021 Add a footer
 WEEDS AND ITS Chemical CONTROL

 What is weed?
• A Great Britain farmer Jethro Tull was the First person
who have defined weed in 1731 in his book
“Horse Hoeing Husbandry”
• A weed is plant growing where it is not desired.
• A weed is a plant growing out of its place
• Any plant not sown in the field by the farmer
is out of place is called weed
Weeds being removed by hand from a parsley patch.

CHARACTERISTICS OF WEEDS
• Weeds are highly competitive and highly adaptable
under varied situations
• Produces larger number of seeds compare to crops
• Reproductive mechanism is far superior to crop plants
• Their seeds germinate earlier and their seedlings grow
faster

• They do not lose their viability for years even under
adverse conditions
• Resistance to herbicides in use thus weeds are called as
“excellent competitors”

Types of weeds
Two types of weed
• Broad leaf weeds
• Narrow leaf weeds

Petty spurge
Petty spurge is a common plant of cultivated ground, such
as gardens, fields and waste ground, and is sometimes
considered a weed

Fumit0ry
Fumitory is a low shrub with gray pointed leaves, and from
a distance the plant can have the wispy appearance of
smoke. Because of this, it received the name "earth
smoke."

Sun spurge
Sun spurge is an annual weed of cultivated fields and
waste places on sandy and clay loams. It prefers light
land. It is common throughout the UK especially in
lowland areas

Wild Carrot
Scientific name : Daucus carota
Common names : wild carrot, bird's nest,
bishop's lace and Queen Anne's lace
Family: Apiaceae
Order: Apiales
Range : temperate regions of Europe and
southwest Asia, and naturalized to
North America and Australia.

Jungle onion
• Scientific name: Asphodilus tenuifolius
• Kingdom : Plantae
• Order : Asparagales
• Family :Xanthorrhoeaceae
• Genius : Asphodelus
• Species : A. tenuifolius
• Locality : wheat Field
• Range : Pakistan

Wild Oats
• Scientific name :Avena fatua
• Common name: Jamdar , Javi
• Order : Poales
• Family : Poaceae
• Genius : Avena
• Species : Avena fatua
• Locality : Wheat fields

Cheat Grass
• Scientific name: Bromus japonicas
• Common name: Silai Ghass
• Order : Poales
• Family : Poaceae
• Genius : Bromus
• Species : Bromus japonicus
• Locality : Wheat field

Wooly distaff thistle
• Scientific name: Carthamus oxyacantha
• Common name: Azghakay Pohli , Kandairi
• Order : Asterales
• Family : Asteraceae
• Genius : Carthamus
• Species : Carthamus oxyacantha
• Locality : Wheat Field ,orchards

Common Goosefoot
• Scientific name: Chenopodium album
• Common name: Bathoo
• Order : Caryophyllales
• Family :Chenopodiaceae
• Genius : Chenopodium
• Species : C.album
• Locality : Wheat Field
• Habit : Annual

Fathen
• Scientific name: Chenopodium murale
• Common name: Sarmay , Bathu
• Order : Caryophyllates
• Family : Amaranthaceae
• Genius : Chenopodiastrum
• Species : C.murale
• Habitat : Wheat , waste land and
vegetables fields
• Habit : Annual

Creeping Thistle
• Scientific name: Cirsium arvense
• Common name: Lahia , Bhur Bhur
• Order : Asterales
• Family : Asteraceae
• Genius : Cirsium
• Species : Cirisum arvense
• Locality : Wheat Fields

Field bindweed
• Scientific name: Convolvulus arvensis
• Common name: prevatay , Ilri , Laihai
• Order : Solanales
• Family : Convolvulaceae
• Genius : Convolvulus
• Species : C. arvensis
• Locality : Wheat and Fruit orchards fields
• Habit : Perennial

Echinochloa colonum in rice
Rumex spp
Xanthium strumarium
Hydrilla Verticillata
Nelumbium speciosum
Typha
Pistia stratiotes
Avena fatua

Effect of weed on crops
• Weeds compete with crop for space, light, moisture and
soil nutrients thus causing reducing in yield.
• Affect quality of farm produce, livestock products such as
milk and skin.
• Act as alternate host for many pest and diseases.
• Cause health problems to human beings.
• Increase the cost of cultivation due to weeding
operation.

• Aquatic weeds transpire large quantity of water,
obstruct flow of water thus affecting fishing , swimming
and recreation.
• Reduce the land value
• Some weeds are poisonous to livestock
• Weeds reduce the efficiency of human beings
and affect movement of farm
animals and workers

Weeds and their effect on crops

Preventive methods of weed management
• Use clean seed that is free from weed seeds for sowing
purpose
• Destroy the weeds before formation of flowers for
avoiding seedling and
further spread of weeds
• The cropped area, bunds irrigation channels, waste
lands etc. should be kept clean or free of weeds

• Inspect nursery stock for the presence of weed
seedlings, tubers, rhizomes etc.
• Farm implements and machinery should be properly
cleaned thoroughly before moving it from one field to
another
• Avoid feeding screenings and other material containing
weed seeds to the farm animals.
• Place mulch on soil surfaces in the garden to
reduce weeds growth.

• Use vigilance (A farmer should inspect his farm
periodically for strange looking new weed).
• Follow legal & quarantine measures

What are Chemical methods ?
• Chemicals which can kill the weeds or control weed
growth are known as herbicides.
• Using herbicides for the control of weeds is called
chemical weed control.
• Herbicides are primarly grouped into:
• inorganic herbicides (Arsenic acid,sulphuric acid,
sodium chlorate)
• organic herbicides (diesel , xylene type of aromatic
oils).

History
• The first major organic chemical herbicide was
developed in France in 1896.
• In the late 1940s new herbicides were developed out of
the research during World War II and the era of the
miracle weed killers began.
• Within 20 years over 100 new chemicals were
synthesized, developed, and put into use.

• The year 1945 marked the beginning of a new era in
chemical weed control
• some of the early herbicides were later deemed unsafe
for humans and the environment and were discontinued
in many countries.

Merits
• Herbicides can be recommended for adverse soil and
climatic conditions
• Herbicides can control weeds even before they emerge
from the soil so that crops can germinate and grow in
completely weed-free environment at early stages
• Herbicide is highly suitable for broadcasted and closely
spaced crops
• Herbicides controls the weeds without any injury to the
root system of the associated standing crop

• It reduces the need for pre planting tillage and controls
many perennial weed species
• It is profitable where labour is scarce and expensive
• its application is highly economical.

Demerits
• Pollutes the environment
• Herbicides must be applied at proper time in each
season
• Excess herbicide residues in soils may affect
succeeding crop
• It requires certain minimum technical knowledge for
selection and use of herbicides
• Affects the soil microbes if the dose exceeds

• Herbicide causes drift effect to the adjoining field
• It requires certain amount of minimum technical
knowledge for calibration
• Leaves residual effects
• Some herbicide is highly costlier
• Suitable herbicides are not available for mixed and inter-
cropping system.
• Causes weed resistance.

Classification of herbicides
 Herbicides may be grouped into two categories:
• selective
• nonselective.

• Selective :
Selective herbicides will not affect the crop but
will kill the weeds
Example:
• clover
• henbit
• Non selective:
Non-selective herbicides will kill all plants
on which it is sprayed or applied. It is also known as total killer
Example:
• paraquat
• glyphosate etc.

Each category may be subdivided into foliage-applied
and soil-applied
• Soil applied herbicides:
Herbicide act through root and other
underground parts of weeds Example :
• Fluchloralin.
• Foliage applied herbicides:
Herbicide primarily active on the plant
foliage
Example :
• Glyphosate
• Paraquat

ANY QUESTION ?
ANY QUESTION ?

weed and its control

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to weed and its control

Similar to weed and its control (20)

Recently uploaded

Recently uploaded (20)

weed and its control