Selecting Herbicide

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Selecting Herbicide

• Original by Brent Niemeyer
• Modified by Georgia Agricultural Education
  Curriculum Office
• July, 2002

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• Effective weed control depends on selecting the
  right herbicide.

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• Herbicides are classified according to the way
  they destroy weeds.

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Types of Herbicide

• Contact Herbicide
• Growth Regulators
• Soil Sterilants

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Contact Herbicide

• Kills plants by exposure
• Works best on Annuals
• May only kill parts of the plant in contact

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Growth Regulator

• Alters growth or metabolic processes
• Absorbed by the roots, stems, or leaves

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• The movement of a herbicide inside of a weed is
  known as translocation

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Soil Sterilant

• Prevents the growth of plants in the soil
• Most useful in greenhouse

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Selectivity of Herbicides
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Selective Herbicide

• Kills only certain plant species and not others

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Selective Herbicide

• Possible to spray in field without injuring crop

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Non-Selective Herbicide

• Kills all plants regardless of species

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Non-Selective Herbicide

• Should not be used in growing crops

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Using Herbicides

• Time of Application

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Herbicides may be applied at three times
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• Pre-plant
• Pre-emergence
• Post-emergence

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Using Herbicides

• Area of Application

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4 general areas of application are used
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Band

• Treating narrow strips with herbicide
• Used in cotton corn

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Broadcast

• Treating the entire area of a field
• Used with pastures
• Not used in row crop

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Directed Appl.

• Treating only selected or targeted plants
• Some use in row crop
• Used a lot with trees

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Spot Application

• Treating only certain areas in field
• Saves cost plus labor
• Protects environment

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Applying Herbicide

• Knowing when and how to apply are important for
  effective weed control