The form in which herbicide is available in the market is known as herbicide formulation.
Objectives of herbicide formulation:
· For easy transport and handling.
· To increase weed killing efficiency.
· To improve storage properties.
· To apply small amount of herbicide equally in the field.
· To increase the spectrum of weed control.
Component of herbicide formulation:
i. Toxicant/active ingredient are the chemical in the formulation which is responsible for weed killing.
ii. Solvent are those which are used in the formulation to solubilized the toxicant so that it can be applied through the common carrier water.
iii. Adjuvent: These are chemicals which are used in the formulation to improve their application, storage and weed killing efficiency.
Classification of herbicide formulation:
The herbicide formulation may be grouped into-
A. Dry formulation:
a. Soluble powder (SP):
Formulated as powder which rapidly soluble in water. The active ingredient and auxiliary agent must be sufficiently soluble in water.
Eg. Dalaphon, Sodium methyl arsenate , salt of most herbicide.
b. Wetable powder (WP):
Finely milled powder that form a suspension when added to water. The active ingredient mostly solid and insoluble in water.
Eg. DCPA, Diphenamide.
c. Granules or pillet:
Formulation in the form of granules which content upto 10% ai increase of granule and (80 – 90%) ai increase of micro granule. This prepared by loading the toxic on some dry inert materials. The size of the granule usually 0.04m in diameter.
B. Liquid formulation:
a. Soluble concentrates:
Formulated in the form of liquid which very easily go into solution when added to water. Active ingredient is liquid, must be soluble in water as well as solvent. Solution is homogenous system.
Eg. 2, 4 – D, Dicumba.
b. Emulsifyable concentrate:
Formulation in the form of liquid which does not go into solution but form an emulsion when added to water, ai is mostly liquid insoluble in water. Emulsion is a heterogeneous system and emulsifying agent must be added.
Eg. 2,4 – D, Bensulphite.