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Package of Practices
  • A compendium of state specific and location specific recommended package of practices are provided under this head. You may be interested to see that, thanks to our IP based customisation, that only your state (the state from where you are accessing RKMP) specific information is available.
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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:

Herbicides that are translocated throughout the plant system and brings the activity at a place distant from the point of application Contact herbicide: Herbicide that kills the plant part that comes in contact with it. Little movement from point of application

III.Based on selectivity:

1. Selective herbicide: Kills only the target plant species (weeds) in a mixed plant population ( crop plants and weeds).

2. Non selective herbicides: kills all the plants that come in contact with the herbicide.

IV: Based on Placement:

1. Soil applied: When applied to soil.

2. Foliage applied: When applied on the foliage of weeds.

V: Based on chemical group:

- Aliphatics - Amides and acetamides: eg. Alachlor and Butachlor

- Arsenicals - Benzoics and phenyle acetates

- Bipyridiliums - Carbamates & Carbanilates

- Dinitroanilines: e.g. Oryzalin, Pendimethalin, Trifluralin

- Diphenyle ethers: e.g. Nitrofen, Oxyfluorfen

- Nitriles

- Phenols

- Phenoxyacids: e.g 2,4-D - Pyridazinones.

- Thiocarbamate: e.g. Benthiocarb.

- Triazines.

- Triazoles.

- Uracils.

 - Ureas

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.

It is active on sensitive plants and inactive on tolerant plants. Herbicide activity is determined by degree of tolerance of the plant to herbicides.

Herbicide selectivity: Refers to phenomenon where in a chemical kills the target plant species in a mixed plant population without harming or only slightly affecting the other plants.

Herbicide selectivity is the single most factors that lead to success of chemical weed control in crops.

Advantages of herbicide: -

Pre emergent herbicides provide early season weed control. This is beneficial as weed competition is morsevere during early stages than later stages. 

Herbicides can be applied to weed control in crop rows where cultivation is not possible.  Very effective than other methods.

Systemic herbicides can control many perennial weed and brush species which cannot be efficiently controlled by other methods.

They reduce the need for pre planting tillage

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.

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 - Closer spacing: Minimize weed competition - Higher density: Minimize weed competition Fertilizer application: - Apply fertilizer after weeding Water management - Continues submergence: Minimize weed growth - Alternate wetting and drying: More weed growth
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.

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.

28
Jul

Cyperus rotundus L. (Purple nut sedge)

 

Family: Cyperaceae.

Description:

 One of the worlds worst weed.

 Height -15-60 cm.

 The plant is swollen and thickened at the base. It has triangular smooth scape, 10 to 60 cm in height, arising from the centre of a basal cluster of narrow grass like leaves of 30-50 cm long and 8 mm wide.

 The leaves are smooth shiny, dark green and grooved on the upper surface.

- The slender underground runners grow out from the base of the stem and form series of black, irregular shaped or nearly round tubers which are 2 cm in length.

Tubers sprout to produce new plants while still attached to parent plant. -The inflorescence arises from stem apex. It consists of a number of slender branches which carries a cluster of spikelets at the end which are brown to dark brown in colour.

Each spikelet consists of 10-30 small crowded florets which ripen to form black triangular nuts.

 The rhizomes give rise to underground tubers which proliferates intensively. Tubers are concentrated in the surface 10 cm soil and store food and are effective means of propagation.

New tubers are produced within 3 weeks after sprouting of individual tuber. Tubers have nodes, internodes and scale leaves.

28
Jul

Cyperus iria L.

 

Family: Cyperaceae  .

Description:

- Widely distributed species in paddy fields.

- Stems 15 to 50 cm high, trigonous

28
Jul

Monochoria vaginalis

 

Family: Pontederiaceae.

Description: Root stock short and sub erect.

 Leaves linear or narrowly ovate with cordate base 5 to 15 cm long.

 Propagation - seed and root stock.

 Thrives well in moist places.

28
Jul

Monochoria vaginalis

 

Family: Pontederiaceae Description: - Root stock short and sub erect. - Leaves linear or narrowly ovate with cordate base 5 to 15 cm long. - Propagation - seed and root stock. - Thrives well in moist places.
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