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Weeds

Weeds
30
Jul

Eragrostis unioloides (Retz.) Nees ex Steud.

Family: Poaceae
Common name: Chinese love grass
General Habit: Annual or perennial grass.
Roots: A fibrous root system.
Stems: Culms are erect growing upto 60 cm height.
Leaves: Leaf blades are flat and narrow.
Flowers: Panicle containing purplish racemes, ascending, branched. Spikelets are ovate, compressed, truncate at base, obtuse at apex, 10-25-flowered, usually purplish in color.
Propagation: Through seeds.

File Courtesy: 
CRRI
Photo Courtesy: 
CRRI
30
Jul

Eragrostis amabilis (L.) Wight & Arn. ex Hook. & Arn

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CRRI
Photo Courtesy: 
CRRI
30
Jul

Isachne globosa (Thunb.) Kuntze

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CRRI
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CRRI
30
Jul

Ischaemum rugosum Salisbury

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CRRI
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CRRI
30
Jul

Dactyloctenium aegypticum (L.) P. Beauv

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CRRI
Photo Courtesy: 
CRRI
30
Jul

Urochloa mutica (Forssk.) T.Q. Nguyen

File Courtesy: 
CRRI
Photo Courtesy: 
CRRI
30
Jul

Axonopus compressus (Sw.) Beauv

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CRRI
Photo Courtesy: 
CRRI
30
Jul

Paspalum conjugatum P. J. Bergius

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CRRI
Photo Courtesy: 
CRRI
30
Jul

Digitaria ciliaris (Retz.) Koeler

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CRRI
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CRRI
30
Jul

Imperata cylindrica (L.) Beauv.

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CRRI
Photo Courtesy: 
CRRI
30
Jul

Eleusine indica (L.) Gaertn

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CRRI
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CRRI
30
Jul

Cynodon dactylon (L.) Pers

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CRRI
Photo Courtesy: 
CRRI
30
Jul

Echinochloa crusgalli (L.) Beauv.

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CRRI
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CRRI
30
Jul

Echinochloa colonum (L.)

File Courtesy: 
CRRI
Photo Courtesy: 
CRRI
29
Jul

Classification of Herbicides

I. Based on time of application:

Pre planting: Herbicides are applied before the crop is planted.

Herbicide with greater toxicity on emerging crop seedlings are usually before crop is planted. Pre emergence: Herbicides are applied before a crop or weeds have emerged. Post emergence: Herbicides are applied after the emergence of weed or crop.

 II.Based on mode of activity: Systemic or translocated herbicide:

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
28
Jul

Chemical weed control

 

Herbicides: Chemicals that is capable of killing some plants (weeds) without significantly affecting the other plants (crops).

Herbicide activity: An herbicide is said to be active or to posses activity if it hinders, inhibits or prevents the germination and growth processes of the plant.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
Photo Courtesy: 
CRRI
28
Jul

Direct methods of weed control

1. Hand weeding: Pulling by hand or using tools like hoe, spade or sickle, Take up one or two hand weeding between 20-42 days after transplanting.

Advantages: Most common, easy and effective. Can be taken up even where random planting is done.

Disadvantage: Costly and laborious.

2. Mechanical weeding: by rotary weeder: Pushed by hand or powered between straight rows.

Advantages: Saves labour.

Disadvantage: Require row transplanting or seeding.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
28
Jul

Complementary practices to control weeds

Land preparation: Puddling before transplanting incorporates weeds and gives rice seedlings a head start over weeds.
Using weed free crop seed and seedlings
Planting methods:
- Straight-row planting: Easy to weed by hand or by mechanical tool
- Random planting : Difficult to weed and to pass mechanical tool
- Transplanting: Weed competition is less
- Direct seeding: Weed competition is severe
Variety:
- Tall growing traditional varieties: Compete more with weeds
- Modern semi dwarf varieties : weed problem is more
Plant spacing and density

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
28
Jul

Preventive methods to control weeds

1. They check weed introduction and spread of weed seeds.

2.  Easy and economical.

3. Preventive measures include use of weed free seeds.

4. weed free seed bed, weed free well decomposed FYM, clean tools and machinery, clean irrigation canals.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
28
Jul

Methods of weed control

Methods of weed control are of three types .

I. Preventive methods.

II. Complementary practices.

III. Direct methods of weed control.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
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