Describes how weed causes yield loss in onion. describes weed flora and their systemic management.

1. Weed Management in OnionWeed Management in Onion
Dr. Subhomay Sinha, W.B.A.S.
M.Sc. (IARI), Ph.D. (IARI)
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2. India is the second largest producer of onion in the world, next to
China, accounting for 26.79 per cent of the world area (3.97 m ha)
and 19.90 per cent of the world production (75.98 m t).
Onion germinates and grows relatively slow and hence weed competition is
more. Critical stage for weed competition up to 40 days after sowing /
transplanting.
Indian onions has two crop cycles, for first cycle, harvesting starts in
November to January (Kharif onion) and the second, harvesting
starts from January to May (Rabi onion).
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5. India is the 2nd largest producer of onion in the world,
next only to China but the productivity of onion in India is
VERY LOW, only 14.21 tons/ ha as compared to China,
where the productivity is 22.00 tons / ha
Among many constrains which has a negative effect on
yield maixmization of Onion, “WEED INFESTATION” is
a major problem.
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6. Onion is regarded as a highly export oriented crop and earns a valuable
foreign exchange for the country.
Onion exhibits greater susceptibility to weed competition due to its
inherent characteristics such as their initial slow growth, shallow root
system and lack of dense foliage.
The effective weed control involves identification of weed flora, method of
weed control and judicious combination of effective weed control methods.
Uncontrolled weed growth reduces the bulb yield of
onion up to 40 – 80 % depending upon the nature
of intensity and duration of weed competition in
onion field
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7. Hand weeding in onion is a common practice in India, but it is a tedious,
expensive and time consuming task due to closer spacing and shallow root
system.
Non-availability of labourers during critical period of crop is a main
bottleneck in onion cultivation.
After bulb formation manual or mechanical methods of weed control
will damage the bulb.
Spraying of pre-emergence herbicides keeps the crop in weed free conditions
during the early stages, while application of early post emergence may be
helpful to reduce damage to the bulb, weed competition and cost of
weeding.
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8. Critical period of weed growth for DIRECTLY SOWN ONION.
Onion faces weed competition during the early stage of crop growth. So the
field should be kept weed free for a period of 45 days after sowing.
Critical period of weed growth for TRANSPLANTED ONION.
The critical period of weed competition for Transplanted onion is between
30 to 40 days after transplantation.
Critical period for weed growth for Onion.
Weed competition is more severe in Kharif onion than
Rabi onion.
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9. Identification of problematic
weed flora of Onion.
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10. Grasses & Sedges
Cyperus rotundus
Cyperus iria
Cynodon dactylon
Setaria glauca,
Digitaria sanguinalis
Panicum repens
Poa annua
Commelina benghalensis
Dinebra retroflexa
Broad Leaved weeds
Parthenium hysterophorus
Phyllanthus niruri
Hibiscus panduriformis
Trianthema portulacastrum
Eclipta alba
Amaranthus viridis
Portulaca oleraceae
Cocculus hirsutus
Corchorus trilocularis
Chenopodium album
Anagalis arvensis
Argemone mexicana
Convolvulus arvensis
Solanum nigrum
Rumex dentatus
Lepidium sativa
Boerhaavia diffusa
Coronopus didymus
Weed flora of ONION
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11. Sedges
Cyperus rotundus Common Name : MuthaGrass
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12. Sedges
Cyperus iria
Common Name : Flat Sedge, Mutha
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13. Grasses Cynodon dactylon
Common Name : Durba, Bermuda Grass
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14. Setaria glauca
Grassy Weeds
Common name :
Sial Lel Grass
Green Foxtail Grass
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15. Digitaria sanguinalis
Grassy weeds
Common Name : Crab Grass
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16. Echinochloa crusgalli
Grassy weeds
Common Name : Shyama Grass
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17. Panicum repens
Grassy weeds
Common Name : Torpedo Grass
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18. Poa annua
Grassy weeds
Common Name : Poa Grass
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19. Eragrostis unioloides
Grassy weeds
Common Name : Chinese lovegrass
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20. Commelina benghalensis
Grassy weeds
Common Name : Krishna Neel
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21. Dinebra retroflexa
Grassy weeds
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22. Dactyloctenium aegyptium
Grassy weeds
Common name : Crow foot grass
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23. Parthenium hysterophorus
Broad Leaved weeds
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24. Coronopus didymus
Broad Leaved weeds
Common name : Swine cress
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25. Phyllanthus niruri
Broad leaved Weeds
Common Name : Hazardana
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26. Solanum nigrum
Broad leaved Weeds
Common Name : Bon Begun
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27. Hibiscus panduriformis
Broad leaved Weeds
Common Name : Jonglee Dheros
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28. Trianthema portulacastrum
Broad leaved Weeds
Common name : Pathar Chata, Punarnaba
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29. Broad leaved Weeds Eclipta alba Common name : Bhringaraj
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30. Broad leaved Weeds
Amaranthus viridis
Common name : Jangli Note
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31. Broad leaved Weeds
Digera arvense
Common name : False Amaranthus
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32. Portulaca oleracea
Broad leaved Weeds
Common name : Moss Rose, Nunia Sak
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33. Cocculus hirsutus
Broad leaved Weeds
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34. Corchorus trilocularis
Broad leaved Weeds
Common Name : Jonglee Paat
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35. Chenopodium album
Broad leaved Weeds
Common name : Bathua
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36. Broad leaved Weeds
Anagalis arvensis
Common name : Scarlet Pimpernel
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37. Broad leaved Weeds
Argemone mexicana
Common name : Sial Kanta
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38. Broad leaved Weeds
Convolvulus arvensis
Common Name : Field Bind Weed
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39. Broad leaved Weeds Rumex dentatus Janglee Palak
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40. Broad leaved Weeds
Polygonum plebeium
Common Name : িচম ট শাক / chimati shaak
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41. Broad leaved Weeds Lepidium sativum
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42. Broad leaved Weeds
Boerhavia diffusa
Common Name : Punornoba
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43. Methods of weed control in Onion
Cultural & Mechanical control methods.
 Best method of weed control in onion is three hand weeding at 20, 40 and 60 days
after transplanting. It results highest bulb and best weed control efficiency.
 Straw mulching technique is a very efficient to suppress weed growth in onion
field.
 Soil Solarization technique can be followed in onion to get rid of problematic
weeds.
 Stale bed technique is also effective for get rid of problematic weeds. Deep
ploughing with a M.B. plough / Disc plough should be used for cultivation for stale
bed technique.
 Operation of cultivators / weeder in onion field is difficult as the plants are softer
type and bulb is just under the soil. So, there is not much scope in mechanical weed
control method.
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44. Oxyflourfen 23.5% EC
It is a selective PRE – EMERGENCE HERBICIDE, used for CONTROLLING
BROAD LEAVED WEEDS, like Chenopodium album, Amaranthus viridis etc
in onion. It controls weeds in both direct sown as well as transplanted onion,
when applied within 2 – 3 days after sowing / transplanting.
Pre-emergence application of oxyfluorfen 400 g a.i. /ha followed by one
hand weeding (HW) at 30 days after transplanting (DAT) results effective
weed control in onion. Doses is 1 – 1.25 mL formulation / L of water.
Chemical methods of weed control
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45. Pendimethalin 38.7% CS
Pendimethalin 38.7% CS is a selective, PRE – EMERGENCE HERBICIDE for Onion. It
controls susceptible ANNUAL GRASSES, SEDGES & BROAD LEAF WEEDS as they
germinate, when applied within 3 days after transplantation / sowing. It controls
Echinochloa colonum, Cyperus rotundus, Cynodon dactylon , Commelina bengalensis
etc. Dose is 2.0 mL formulation / L of water.
Chemical methods of weed control
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46. Fenoxaprop-p-ethyl 9.3% EC
Chemical methods of weed control
It is A POST – EMERGENCE, selective herbicides, used for controlling Echinochloa sp.,
Dactyloctenium aegyptium and other GRASSY WEEDS in onion. It is sprayed when
weeds are in 3 - 4 leaf stage. This herbicide is taken up via the green plant tissues of
the weed (i.e. leaves, stem etc) and not via the roots. Its dose is 1.25 – 1.50 mL / L. It
works independently of soil type.
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47. Propaquizafop 10% EC
Propaquizafop 10 % EC is a POST – EMERGENCE
SELECTIVE HERBICIDE, used for the control of a
wide range of GRASSY WEEDS in onion.
Propaquizafop is a systemic herbicide, which is
quickly absorbed by the leaves and translocated
from the foliage to the growing points of the
leaves and roots of the sprayed weeds. Optimal
activity is achieved when applied early and weeds
are actively growing, i.e. 2 – 4 leaf stage of grassy
weeds.
In onion, it best controls the following weeds :
Digitaria sanguinalis, Dactyloctenium aegyptium,
Echinochloa crusgalli, Phalaris minor etc.
Chemical methods of weed control
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48. Quizalofop – ethyl 5% EC
Quizalofop-ethyl 5% EC is a POST – EMERGENCE HERBICIDES, effectively
controls the narrow leaf weeds like GRASSES, SEDGES etc. it very quickly
absorbed by the weeds and translocate to all parts. It has excellent rain
fastness, rain, even one hour after spray does not affect its effectiveness. The
affected weeds are unable to regenerate. Weed leaves turn puplish/ red within
5-8 days after application and within 10-15 days are completely killed.
Chemical methods of weed control
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49. Propaquizafop 5 % + Oxyfluorfen 12 % EC
This combination product is a strong contact and
broad spectrum herbicide for controlling both
BROAD LEAVED AND GRASSY WEEDS in Onion.
It is applied as EARLY POST EMERGENCE HERBICIDE on
weeds, when they are at their 2 – 4 leaf stage.
It controls the following weeds in onion :
GRASSES : Digitaria sanguinails, Dactyloctenium
aegypticum, Echinochloa colonum, Echinochloa crusgalli,
Eleusine Indica .
BROAD LEAVED WEED : Chenopodium album, Digera
arvensis, Amaranthus viridis etc.
Chemical methods of weed control
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