Rainfed rice - IRRI books - International Rice Research Institute

RAINFED RICE A SOURCEBOOK OF BEST PRACTICES AND STRATEGIES EASTERN INDIA
Caution
Repeated use of a certain method
of weed control independently may
result in an undesirable shift in
weed flora.
When using herbicides, remember:
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to apply herbicides strictly at the
recommended dose and crop stage.
As older weeds are not suppressed or
killed, there should not be any weed
with more than one to two leaves for
early post-emergence/pre-emergence
spraying; and
to change the herbicide each year to
avoid an undesirable shift in weed
flora and to stop resistance to the
herbicide. A large number of herbicides
suitable for rice have varying degrees
of weed control efficiency, such as
anilofos, butachlor, thiobencarb,
pendimethalin, pretilachlor,
pyrazosulfuron ethyl, oxadiazon and
oxyfluorfen, etc.
Hand weeding
Hand weeding is the removal of weeds by hand
or khurpi. It is done in both nurseries and main
plots. Complete the first hand weeding within 20
days of sowing when the weeds are of suitable
size for removal.
For nurseries, one weeding is enough. However,
in main plots, depending on the duration of the
variety and weed growth, two to three hand
weedings may be needed. The interval between
the first and second weedings must not exceed
three weeks.
Mechanical weeding
Mechanical weeding is a method that uses
different types of weeder or hoe, such as the
sweep hoe, wheel hoe, Japanese paddy weeder
and pulo weeder. In broadcasting, however, the
seeded rice weeder or hoe cannot be used.
Mechanical weeding is best practiced only when
the physical condition of the soil, particularly
moisture or water, is at an optimum level for
moving tools. Mechanical weeding can be'
combined with hand weeding.
Chemical weed control
Phytotoxic chemicals used to suppress weed
growth in crops are known as herbicides.
Chemical weeding