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Genomics and Applied Biology 2015, Vol. 6, No. 3, 1-14
http://gab.biopublisher.ca
4
and resulted in higher bulb yield in onion.
Mechanical Method
Mechanical weeding is one of the oldest, but the most
common methods of weed control in upland crops.
Hand weeding with simple weeders is common. These
simple weeders are cheap, more efficient and suitable
for farmers to reduce the cost of crop production and
improve crop yield to a great extent. It is not only safe
to the environment, but also safe to the user.
Mechanical weed control is comparatively faster and
less labour intensive than hand weeding (Chivinge,
1990). Use of selective herbicides together with
mechanical methods of weed control was
recommended by Rapparini (1994). Duraisamy and
Tajuddin (1999) reported that mechanical weeding is
preferred to chemical weeding because weedicide
application is generally expensive, hazardous and
selective, besides mechanical weeding keeps the soil
surface in better aeration and facilitates in moisture
conservation. Power weeder was found useful for
weeding in between standing rows of cash crops like
cotton, tapioca and grape. The weeder could cover an
area of one ha day
-1
in 8 hr. The cost of weeding by
this machine comes to only one-third of the weeding
cost by manual labourers (Tajuddin, 2006). Yadav and
Pond (2007) reported that mechanical weed control
not only uproot the weeds between the crop rows but
also keep the soil surface loose, ensuring better soil
aeration and water intake capacity. Weed morphology
and stage of growth would influence the selection and
efficacy of weeding implement.
Gore
et al
. (2010) reported that cycle hoe weeder
produced significantly higher grain yield and found to
be effective in controlling grass as
well as broad
leaved weeds at 30 (69 and 44 per cent) and 60 DAS
(63 and 67 per cent) in soybean. Effective and
economical weed management in rainfed pigeonpea was
obtained either by pre-emergence application of
pendimethalin at 0.75 kg ha
-1
on 3 DAS followed by
one weeding with oleo weeder on 45 DAS or
pre-emergence application of pendimethalin at 0.75 kg
ha
-1
on 3 DAS followed by one weeding with wheel hoe
weeder on 45 DAS (Gowsalya
et al
.
,
2010).
Jakhar
et al
. (2012) pointed that two rotary weeding at
20 and
40 DAS reduced the growth of weeds resulted
in higher weed control efficiency in
soybean over all
other weed control treatments.
Chemical Method
Inadequate weed management practice is one of the
major causes for low yield of crops. The conventional
method of weed control through hand weeding is
costly and non-available at critical stages. Herbicidal
weed management becomes competitive and a
promising way to control weeds at least at first few
weeks after sowing of the crop. Studies by Yaduraju
et
al
. (2006) reported that in India, herbicides are being
used in approximately 20 million hectares, which
constitute about 10 per cent of the total cropped area.
Pre-emergence herbicides
Pre-emergence herbicide application can help to
control the weeds in the early crop growth stage.
Baker and Terry (1991) reported that pre-emergence
herbicide use would be appropriate not only for
minimizing weed competition, but also for reducing
the work load during the peak labour demand period,
avoiding at least one or two intercultivation during the
first 3 to 4 weeks of crop growth and to control weeds
effectively. Guggari
et al
. (1995) observed that 30 to
55 per cent of the weeds can be controlled by
pre-emergence application of herbicides. Crop-weed
competition is minimized by pre-emergence spray of
herbicides resulting in higher crop yield (Berevadia
et
al
.
,
1996).
Metribuzin
Higher weed control efficiency (93%) was recorded
with pre-emergence application of metribuzin followed
by methabenziozuron (91%) and lower in oxyfluorfen
with the efficiency of 80 per cent in potato (Rao and
Singh, 1988). Pre-emergence application of
metribuzin at 0.75 kg ha
-1
was found most effective
closely followed by oxyfluorfen (0.3 kg ha
-1
) against
both broad leaved and grassy weeds. The higher weed
control efficiency (88%) and benefit cost ratio were
recorded in PE metribuzin treated plot in potato
(Jaiswal and Grewal, 1991). According to Maliwal
and Jain (1991), Singh (1992) and Suryanarayana
Reddy (1993), pre-emergence application of
