3. SUBMITTED TO:
Dr . Shankarnarayan sir
Department of Agronomy
Sericulture college Chintamani
Submitted by:
Anil Kumar. G.N
I BSc (Agri)
ID.No: ALC3004
Sericulture College Chintamani
5. The definition of weeds is predicated on human
perception , desire and needs.
A weed is a plant which interferes with human
activity or welfare.
It is also defined as plant growing in a place
where it is not desired at a particular point in
time.
6. Classification according to habitat.
weeds occur in crop lands , orchards
, forests. They may be aquatic , terrestrial
and subterranean.
Aquatic: These weeds grows in water.
Ex: masilea guadrifolia, and some
convolvulaceous plants are water
hyacinth, hydrilla, algae, reed grass etc.
7. Terrestrial: All mesophytic weeds.
Roots of these weeds remain concentrated in
20-30 cm depth from surface.
Subterranean: These weeds are not fully
subterranean , their roots , rhizomes , remain
underground and multiply.
9. Classification according to life cycle.
These may be annual , biennial or
perennial.
Annuals : They may mostly complete their
life cycle in a season.
Biennials : These weeds complete their life
cycle in 2 seasons/years.
Perennials: These weeds are found almost
every where in cultivated lands
, uncultivated lands , waste lands.
10.
According to cotyledons weeds are classified
as monocotyledon or dicotyledon species.
The monocots are narrow leaved weeds of
grass family , dicots are broad leaved.
11. On this basis weeds may be woody , semi
woody , and herbaceous.
Herbaceous weeds are more common than
others. Ex : lantana camara, acacia arabica, are
common woody species.
12. Weeds flora and their characteristics are different in
different types of crops . some may be common.
According to their association they may be upland rice
association weeds , low land rice association weeds
, wheat association weeds, pulse association weeds. Etc
Ex: In mustard-cleome viscosa and cleome menaphylla.
In horse gram- tephrosia purpurea. In rice- O.sativavar
fatua .
13. These may be absolute weeds , relative
weeds, rogues .
Rogues means mixture of other variety in a
variety grown.
14. Some weeds grow as parasites on other crops.
They may be considered as loaders.
These are cuscuta , orobanchae , striga, etc.
