Brief introduction to weeds

1. Classification of Weeds

2. 1. Classification Based on Crop Season
 A. Annual Weeds:-
 Those weeds which complete their life cycle within one growing season. They may be summer
annuals and winter annuals.
 Summer weeds:-
 Weeds growing from April-May to September-October and affecting summer crops e.g. Tandla and
Itsit etc.
 Winter weeds:-
 Weeds growing from September-October to April-May and affecting winter crops e.g. Jangli jai and
Bathu etc.

5.  B. Biennial Weeds
– Those weeds which complete their life cycle in 2 years or two growing seasons. They have
determinate type of growth i.e. complete their vegetative growth in one season and
reproductive stage in the later. There is not any problem weed in Punjab from this category.
However, some examples of biennial weeds are Alternaria echinata, Daucus carota etc.

6.  C. Perennial weeds
– Weeds growing throughout the year and affecting summer, winter or both season crops
are called perennial weeds. e.g. Jangli cholai and Lehli etc.

8.  D. Spring weeds
– Some of the perennial , summer or winter weeds affecting spring crops like
cholai, senji, dranak and jangli palak etc.

10. 2. Morphological Classification
 Dicot weeds:-
 Most of the weeds with
reticulate venation of simple or
compound and broad leaves are
called dicotyledonous weeds.
Some examples of dicot weeds
are billi boti, pohli, lehli, jangli
mata etc.
 Monocot weeds:-
 Weeds with parallel venation of
long narrow leaves, grass like
plant structure and seedlings
having one cotyledonary leaf are
termed as monocot weeds. They
may be grouped into grassy
weeds and sedges.

12. Monocots groups
 Grassy weeds:-
 Weeds of graminae family
having ligulate, sheathing
leaves, stem consisting of
hollow internodes and
fibrous adventitious roots
are known as grassy weeds
e.g. khababal, swanki, sittee
booti etc.
 Sedges or trigonous leaved weeds:-
 Trianguar stemmed weeds
lacking ligules, auricles,
their leaf sheaths are
continuous around stem
and belonging to
cyperaceae family. Some
examples are deela, bhoin
etc.

14. 3. Classification based on mode
of propagation
i. Propagated through seeds:-
i. Most of the weeds reproduce themselves through seeds and are easily
controlled through pre emergence herbicides.
ii. Propagated through vegetative parts:-
i. Such weeds are difficult to control e.g. deela and khabbal.
iii. Propagated through seed and vegetative parts:-
i. They perinate themselves through both methods. They are difficult to control
through a single methods e.g. Akash bale, Dodhak, Baru etc.

16. 4. Physiological Classification
 C3 plants:-
 Photosynthetically less
efficient plants, which may
not compete well with crops
as stiffy as C4 plants e.g.
Jangli jai, Lehli, Jangli palak
etc.
 C4 plants:-
 Weeds more efficient in
their light harvest capacity.
Respiratory CO2 is reutilized
in these plants e.g. Moti
khabbal, Lunak, Baru etc.

18. 5. Classification according to
nature of stem
 Herbacious:-
 Most of the weeds are herbaceous stemmed, succulent and susceptible to post emergence
herbicides e.g. Euphorbia helioscopia, fumaria indica etc.
 Semi woody:-
 Weeds having herbaceous stem in their early growth period and tending to become woody
in their advanced growth stages e.g. Digera arvensis, Rumex dentatus etc.
 Woody:-
 Most of the perennial weeds having stiff stem from their initial growth period. These weeds
are very difficult to control in their advanced stages e.g. Calatropis procera, Datura fastuosa
etc.

20. 6. Miscellaneous
– Noxious weeds:-
– Weeds under this
classification are those
plants which are
undesirable, troublesome
and difficult to control.
Noxious weeds have
immense capacity of
reproduction, perpetuation
and disprsal e.g. khabbal,
motha, kalali etc.
– Objectionable weeds:-
– Those noxious weeds whose
seeds are difficult to
separate when mixed with
crop seeds e.g. kasni, piazi,
itsit, warri booti etc.

22. 7. Classifiction based on their
habitat and soil categories
– Some weeds prefer healthy soils, some flourish in salt affected and others are
adopted to sandy and loam soils e.g. piazi, pohli, madhana, oont ktara, qulfa
etc.