WEED management – DEFINITION OF WEED – LOSSES

 WEED management – DEFINITION OF WEED – LOSSES AND
USES OF WEEDS – WEED INFLUENCE ON CROP
PRODUCTION – strategies OF WEED management

First person to use the term weed is ‘Jethro Tull’

1. A weed may be a plant growing wherever it's not wished.

2. Weed is Associate in Nursing unwanted plant.

3. A plant with –ve price.

4. A plant interferes with meant use of land.

5. A plant growing with desired plant.

Losses because of weeds:

1. Weeds vie with crop plants for resource like light-weight, moisture, nutrients.

2. Weeds cause reduction in crop yields. Among the annual agriculture loss in

India. Weeds accounts for forty fifth, insects half-hour, diseases two hundredth others five-hitter.

3. Weeds increase price of cultivation.

4. Weeds ar alternate hosts for crop pests and diseases.

S. little doubt Crop Pest/disease Alternate host.

1. Rice Stem borer Echinochlon sp.

2. Groundnut Stemrot genus Parthenium

3. Castor bushy catlepiller herb

4. Redgram Gram catlerpiller Amaranthus, Datura

5. Weeds scale back the standard of turn out.

Ex: Cuscuta as Associate in Nursing admixture with medick spoils seed quality.

• alliaceous plant and wild garlic as weeds in fodder crops impart off-flavour to exploit.

Xanthium impairs wool quality of sheep

6. Weeds cause human health issues.

• hypersensitivity reaction by bastard feverfew

• Mosquitoes inflicting protozoal infection. yellow jack inflammation and disease breed on

Pistia and herb

• allergic rhinitis and respiratory illness caused by Franseria sp.

• eczema caused by Amrosia and genus Helenium

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Itching and inflammations caused by hair of Urtica sp.

7 Weeds cause animal health issues.

• poisonous plant camara induces hypersensitivity to light-weight.

• shrub sp. cause diarrhoea and blood strains in milk.

• sorghum toxic to cows.

8 issues of water contamination.

• Render drinkable unfit.

• scale back flow of water in irrigation channels

• scale back flow of water in irrigation channels. Ex: Eichornia monocot genus.

9 Reduction in land price, because of nut sedge and Cynedon, dactylon

• Allelopathy: Harmful affects of plant because of analysis and phytochemicals on

other plants.

• Avenafatua: have an effect on germination of weed. Seed exudates.

Benefits from weeds:

• Constant supply of latest genes

• monocot genus spontaneum may be a wild cane employed in breeding.

• Fodder price

• grass

• As leaflike vegetables, Amaranths and genus Celosia.

• As inexperienced manures – Tephrosia

• Have healthful price

• Leucas aspera – bite

• Phyllanthus niruri – jaundice

• Calotropis – for internal organ troubles

• Argemona mexicana – skin disorders

• Imperata cylindrical – thatching

• genus Cynodon for conservation.

Critical amount of crop – weed competition:

it's the amount of crop growth throughout that weeds cause nice loss to the crop and

this is the amount throughout that the crop must be maintained in a very weed free

environment. Weed competition is severe in early stages of crop growth. Generally

crops should be maintained weed free throughout the primary 1/3rd amount of life cycle.

Principles of crop weed competition:

• Time of emergence of crop Vs weed.

• style of weed species concerned

• Weed no

• Weed wt.

Bioherbicides:

• infective agent like bacterium, fungus, virus ar sprayed on weeds for his or her management.

• Strangler vascular plant – Marrenia odorata – In citrus gardens in USA is controlled by

fungus. Phytophatora palmivora (Trade name: Devine).

• Aeschymomene Virginia (Joint vetch) – In rice and soybean in USA is

controlled by Colletotrichum gleasporoides (Trade name: Collego).

• several aquatic weeds ar controlled by carp fish (Grass carp, silver carp,

common carp).

• Competition plants – genus Parthenium it controlled by Cassia sericea.

• Chemical strategies – Weedicides / herbicides ar the chemicals used for weed

control.

• Dinozeb was the primary chemical introduced in 1933 in Bharat. 2,4-D was 1st

weedicide tested in 1946. at this time thirteen of total chemicals employed in Bharat ar

weedicicdes (75% insecticides), V-E Day fungicides and four nada others).

• Weedicides ar effective and supply weed management from the terribly 1st day, safe

to crops; cultural and mechanical strategies is avoided and perennial weeds

can be controlled.

Herbicides – 2 types:

1. Inorganic Ex: CuSO4 (dicots)

H2SO4 (Cereals), Naclo3 (deep frozen perennials)

2. Organics Ex: Amides – Butachlor

Dinitro anilines - Fluchloralin

Thio carbamates - Benthiocarb

Bi pyridyliums – weedkiller

Triazines – herbicide

Phenoxy carboxylic acid acids – a pair of, 4-D

Substituted ureas – Diuron, monuron, isoproturon.

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Based on time of application herbicides ar sorted as below:

1. Pre-plant incorporation (PPI)

2. Pre-emergence

3. Post-emergence

Based on selectivity:

1. Selective

2. Non-selectivity

Based on mode of Action:

1. Systematic

2. Contact

Formulations:

1. Wettable powder (WP)

2. Soluble powder (SP)

3. Emulsificable concentrate (EC)

4. Sol concentrates (SC)

5. Granules (GR)

6. Fumigants

Based on methods:

1. Foliage application

2. Blanket application

3. Direct spray

4. Protected spray

5. Spot treatment

Soil Application:

• Surface application

• Sub surface layering

• Broadcast and band placement

• coating

Formulations

• Active ingredients (ai) – a part of the formation i.e., directly liable for

herbicide have an effect on.

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• Acid equivalent – a part of the formulation that in theory is born-again

into acid.

• Herbicides carriers – Water (for spraying) sand (for broadcasting)

• Herbicides ar accessible with completely different trade names.

• Why herbicides aren't standard in Bharat.

1. ton of human resource.

2. giant space is rainfed (where effectiveness is uncertain)

3. Lack of awareness

4. Intercropping things (limited convenience of selective herbicides for each

the crops)

5. tiny holdings with family labour