Presentation
Herbicide Formulations
HERBICIDES
o Herbicides, also commonly known
as weedkillers or weedicides used to
kill unwanted plants in the cropped
areas.
o Herbicides are the substances that
are toxic to plants, used to destroy
unwanted vegetation.
Types of Herbicides
Herbicides are available in two main types:
1) Nonselective Herbicides
The nonselective variety is used to kill all
growth and is generally reserved for
agricultural use or for clearing large or
heavily overgrown areas.
Example: Roundup
Types of Herbicides
2) Selective Herbicides
Selective
herbicide is used to target
certain types of plant life. This form
works to curb growth, usually through
some type of hormone disruption, and
should not affect other vegetation.
Example: Dual gold
HERBICIDE FORMULATION
The herbicide product you purchase is rarely
made up only of active ingredients. Often the
herbicide is diluted in water or a petroleum
solvent, and other chemicals are added before
the product is offered for sale. These other
chemicals may include wetting agents,
spreaders, stickers, extenders, or diluents.
This mixture of active and inert ingredients
(inactive) is called a formulation of herbicide.
Purpose of formulation
To enable farmers to disperse the herbicide in a
convenient carrier such as water and to allow to spray in
this convenient carrier.
To enhance the phytotoxicity of the herbicide.
To handle, store and spray properly-Easy to handle.
To improve the longevity of the herbicide-Improve shelf
life.
To protect the herbicide from bad weather of
environment during storage.
Practical value; Pure forms of herbicides are practically
useless to us and rarely available as pure chemicals.
TYPES/FORMULATION
1) Dry formulations
2) Liquid formulations
3) Adjuvants
4) Salts & Esters
DRY FORMULATIONS
I. Granules(G)
II. Pellets(P) or Tablets(TB)
III. Dust(D)
IV. Wettable Powder(WP)
V. Soluble Powder(SP)
VI. Water Dispersible Granule(WDG)
DRY FORMULATIONS
Granules (G)
• Granules consist of the active ingredient
absorbed onto coarse particles of clay or
other substance, and are most often used
in soil applications.
• These formulations can persist for some
time and may need to be incorporated into
the soil.
• The amount of a.i. ranges from 1 to 15%.
• Examples: Top-Site, Sprakill 13, Arsenal
0.5g
DRY FORMULATIONS
Pellets (P) or tablets (TB)
• Pellets are similar to granules but tend to be
more uniform in size and shape.
• Pellets provide a high degree of applicator
safety.
• Example: Spike 20p
Dust (D)
• A dust is a finely ground pesticide combined
with an inert or inactive dry carrier. They can
pose a drift or inhalation hazard.
DRY FORMULATIONS
Wettable Powder (WP or W)
• Wettable powders are finely ground solids, typically
mineral clays, to which an active ingredient is absorbed.
• These dry preparations look like dust, contain a high
percent active ingredient (usually 50 percent or more)
and are mixed with water for application.
• Good agitation (mixing) is needed in the spray tank to
maintain the suspension.
• Example: Spike 80W.
DRY FORMULATIONS
Soluble Powder (SP)
• This is a dry formulation that contains a high percent of
(usually above 50 percent) active ingredient.
• Soluble powders look like wettable powders but they
form a true solution when added to water.
• After dissolving, no more agitation is usually needed.
• Few herbicides are available in this formulation because
few active ingredients are soluble in water.
• Inhalation hazard is a characteristic of this formulation.
• Example: Solution
DRY FORMULATIONS
Water-Dispersible Granule(WDG) or Dry Flowable (DF)
• Dry flowable are manufactured in the same way as
wettable powders except that the powder is aggregated
into granular particles.
• They are mixed with water and applied in a spray
exactly like a wettable powder.
• This dry formulation usually contains 70 to 90 percent
active ingredient.
• Constant agitation is required.
• Example: Diuron 80, Escort
LIQUID FORMULATIONS
• Liquid formulations do not exhibit the
variety of physical forms possible with dry
formulations. However, liquid
formulations differ markedly in the nature
of their characteristics that influence
selection, rate and method of application,
and environmental impact.
LIQUID FORMULATIONS
Water-Soluble Concentrate (WSC)
• Water-soluble concentrates to form a true solution
when added to water and is applied with water as the
carrier.
• These formulations are essentially nonvolatile. There
are usually 2 to 6 pounds of active ingredient per gallon
of the formulation.
• Agitation is not necessary to maintain the herbicide in
solution.
• Example: Arsenal, Formula 40, Roundup Pro,
LIQUID FORMULATIONS
Emulsifiable Concentrate (E or EC)
• An emulsifiable concentrate formulation usually
contains the active ingredient, one or more petroleum
solvents, and an emulsifier that allows the formulation
to be mixed with water.
• Emulsifiable concentrates usually contain 2 to 8 pounds
of active ingredient per gallon.
• These concentrates are soluble in oil and form an
emulsion in water.
• There usually is a dermal (skin contact) hazard
associated with this formulation.
• Example: Garlon 4
LIQUID FORMULATIONS
Flowable or Aqueous Suspension (F, L or AS)
• In this formulation, very finely ground solid material is
suspended in a liquid.
• Liquid flowable usually contain a high concentration (4
pounds or more) of active ingredient and are mixed with
water for application.
• They seldom clog spray nozzles and they need only
moderate agitation.
• Example: Diuron 4L
ADJUVANTS
• An adjuvant is any material added to a
herbicide mixture that facilitates mixing,
application or herbicide efficacy. An
adjuvant enables an applicator to
customise a formulation to be most
effective in a particular situation.
ADJUVANTS
• Important types of activator adjuvants
include:
1. Surfactants
2. Stickers
3. Drift inhibitors
4. Anti-foaming agents
ADJUVANTS
Surfactants
• Surfactants are the most important adjuvants.
• They are chemical compounds that facilitate the
movement of the active herbicide ingredient into the
plant.
• They may contain varying amounts of fatty acids that
are capable of binding to two types of surfaces, such
as oil and water.
ADJUVANTS
Stickers
• A sticker is an adjuvant that causes the
herbicide to adhere to the plant foliage, thus
reducing the possibility that rain will wash it off
before the herbicide can penetrate.
ADJUVANTS
Drift Inhibitors
• Other adjuvants serve other specialised functions.
• Drift inhibitors or thickeners are used to control drift.
• These may be powders, granules, or liquids that cause the spray
solution to be more cohesive.
Antifoaming Agents
• Air gap filling or mechanical agitation in partially full tanks can
cause excessive foaming.
• Antifoaming agents cut down on frothing so that the tank can be
filled more easily.
SALTS AND ESTERS
• Many herbicidally active compounds are
acids that can be formulated as a salt or
an ester for the application. Once the
compound enters the plant, the salt or
ester action is cleaved off allowing the
parent acid (active ingredient) to be
transported throughout the plant.
Misuse of Herbicides
Applying improper rate.
Applying wrong herbicide.
Improper calibration.
Improper method of application.
Improper timing of herbicide application.
Improper soil incorporation.
