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

 Effective weed control depends on selecting the right herbicide.

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

Types of Herbicide  Contact Herbicide  Growth Regulators  Soil Sterilants

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

Growth Regulator  Alters growth or metabolic processes  Absorbed by the roots, stems, or leaves

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

Soil Sterilant  Prevents the growth of plants in the soil  Most useful in greenhouse

Selectivity of Herbicides

Selective Herbicide  Kills only certain plant species and not others

Selective Herbicide  Possible to spray in field without injuring crop

Non-Selective Herbicide  Kills all plants regardless of species

Non-Selective Herbicide  Should not be used in growing crops

Using Herbicides Time of Application

Herbicides may be applied at three times:

F Pre-plant F Pre-emergence F Post-emergence

Using Herbicides Area of Application

4 general areas of application are used:

Band  Treating narrow strips with herbicide  Used in cotton & corn

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

Directed Appl.  Treating only selected or targeted plants  Some use in row crop  Used a lot with trees

Spot Application  Treating only certain areas in field  Saves cost plus labor  Protects environment

Applying Herbicide  Knowing when and how to apply are important for effective weed control