18 3 4 formulations

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Pest i c ide Formulat ions Page 4 -57

Part 4:

Pesticide Formulations

What�s in this Chapter:

What Is a Pesticide Formulation?

How to Choose a Formulation

Different Types of Formulations

Combining Different Formulations



Page 4 - 58 Pr i vate Pest i c i de App l i cator T ra in ing Manua l

Key Questions About Pesticide

Formulations

nWhy isn’t th ere on ly on e kind of pest icide formu lation ? Wouldn ’t it be

simpler?

nWhat d ifferen ce can a pest icide’s form u lation m ak e on crop injury? pes t

control? app lication equipment?

n How would you k now if you could ta nk -mix two pesticides with differen t

formulations?

What Is a Pesticide

Formulation?

A formulation is a mixture of the active ingredient in a pesticide withother inert (inactive) substances. Different formulations may be used

differently. Some are to be used direct from the package, while others need

to be diluted with water, oil, or other carriers. The reason for mixing the

active ingredient with other substances is to make handling and

app lication s afer, easier, an d m ore accura te.

Some active ingredients do not dissolve in water or oil. Others can only be

manufactured as solids. Still others are liquids or gases in their original

forms. By mixing the active ingredient with other materials such as

solvents, wetting a gents , stickers, powders, or gran u les, ma nu factu rers

produ ce formu lations tha t can be ha nd led accura tely and s afely by

ap plication m ach inery. A few pesticides ar e n ow formu lated for con trolled

release. These pesticides allow the active ingredient to be slowly releasedafter app lication. This provides b etter contr ol for certain p ests at p ossibly

lower rat es a n d over a longer period of time.

How to Choose a Formulation

A single pesticide is often sold in different formulations. Different

formulations of the same active ingredient often behave differently. For

example, some types of formulation may mix in water better, while others

ma y increas e the ch an ce of crop injury. Choose th e formu lation tha t is

suitable for the job. Things to consider include:

n Percent of active ingredient.

n Ease in handling and mixing.

n Personal safety risk.

n Type of environment (agriculture, forest, urban, etc.).

n Effectiveness against the pest.



Pest ic i de Formulat i ons Page 4 -59

n Hab its of th e pest.

n Th e crop to be protected.

n Type of ap plication m ach inery.

n Dan ger of drift or ru n off.

n Possible inju ry to crop.

n Cost.

Different Types of

Formulations

Emulsifiable concentrates (EC) are liquid formu lations in which the

active ingredient has been dissolved in oil or other solvents and an

emu lsifier ha s been add ed so tha t th e formu lation can be mixed withwater or oil for sp raying. ECs, along with wettab le powders (WP) are th e

most widely us ed formu lations . An EC u su ally conta ins two to six poun ds of

active ingredient per gallon. ECs are easy to handle and require little

agitation. Some crops are sensitive to the ECs of some insecticides; in

these cases use a different formulation of the active ingredient (for

exam ple, a wettab le powder).

High co nce ntrate liquids, spray co nce ntrates, and ultra low volume

(ULV) concentrates ma y be thou ght of as special EC formu lations . They

usually contain a high concentration of the active ingredient, as much as

eight or m ore poun ds per gallon. Most a re ma de to be m ixed with water or

oil. ULV concentrates are made to be used directly without dilution; they

contain little but the pesticide itself.

Low co nce ntrate liquids o r oil solutions (S) contain low amou nts of the

active ingredient. They are made to be used as purchased, with no further

dilu tion. Th is type of formu lation is often sold for u se in controlling

hou sehold pests, for mothp roofing, or in b arn s as a s pace spr ay or spray for

livestock.

Flowable liquids (F or L) are m ade with active ingredients tha t do n ot

dissolve well in water or oil. The active ingredient is very finely ground and

su spen ded in a l iquid along with su spen ding agents, ad ju van ts, an d other

ingredients. The formu lation can then be m ixed with water an d a pplied.

Flowables do n ot clog spray n ozzles, requ ire moderat e agitat ion, a nd in

ma ny ways are as eas y to ha nd le as EC formu lations .

Solutions and water soluble co nce ntrates (S) are liquids in th eir original

state and are completely soluble in water or other organic solvents.

Properly prepared solutions do not leave unsightly residues and will not

clog spra y equipmen t. But some can dam age crops, so you ma y have to use

another formulation.

Encapsulated pesticides are a fairly new type of formu lation. The a ctive

ingredient is contained in an extremely small capsule. The capsules are

su spen ded in a l iquid. This formu lation is m ixed with water an d a pplied

with conventional sprayers. It is relatively easy and safe to use, but can be



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a significant hazard for bees because the bees may take the capsules back

to th e h ive with p ollen .

Dusts (D) are a very finely ground mixture of the active ingredient

combined with talc, clay, powdered n u t h u lls, or other s u ch m aterials. They

are used dry; never mix them with water. Some active ingredients that

ma y ha rm a crop if app lied as an EC can be app lied withou t har m as a du st.

The percentage of active ingredient is usually quite low. Dust formulationsare available for us e on seeds, p lan ts, an d an ima ls.

Granules (G) are dry particles ma de u p of porous m aterials, su ch a s corn

cobs or walnut sh ells, to which th e active ingredient ha s b een a pplied. The

percentage of active ingredient is lower than in an EC but usually higher

tha n th at of a du st formu lation. They are usu ally safer to apply tha n E Cs or

du sts. Gran u lar pesticide formu lations are m ost often u sed as soil

treatments. They can be applied directly to the soil or over plants, since

th ey us u ally do not cling to plant foliage.

Wet table powde rs (WP) are d ry powdered p esticide form u lations . Th ey look

like dusts but, unlike dusts, they contain wetting and dispersing agents.

They are usually more concentrated than dusts, containing 15 to 95

percent active ingredient. The formulation does not form a true solution,

so agitation is requ ired in th e spra y tank to keep the formu lation in

su spen sion. Som e active ingredients which can not be formu lated into ECs

can be formu lated into WPs. Good wettable powder formu lations sp ray well

an d do n ot clog nozzles, bu t th ey are abra sive to pu mp s a nd nozzles. Most

WPs are less likely than ECs to damage sensitive plants.

Soluble powders (SP), like wettable powders, are dry formulations, but

when ad ded t o water th ey diss olve comp letely an d form solutions . Agitation

in the s pray tan k m ay be n eeded to get them to dissolve, bu t, once in

solution, agitation is not needed. The percentage of active ingredient is

u su ally high compared to ECs an d WPs. Not man y SP formu lations are

available.

Dry flowables look like granu les, bu t are u sed in the s am e way as wettable

powders. They have several advantages over WPs: they can be poured from

their conta iner an d m easu red by volu me like a liquid; they are sa fer to

handle because there is l i t t le dust in the air when they are measured and

mixed. They contain very high concentrations of active ingredient.

Press ure-liquefied gases and fum igants. Some active ingredients are

gases th at k ill when abs orbed or inh aled. They are often s tored un der

pressure. Under pressure, the gas may turn to l iquid. These formulations

ma y be injected into th e soil, released u nd er tarps , or released into a grain

storage elevator. Some liquid formu lations not s tored un der press u re tu rn

to gases or vapors a fter th ey ha ve been ap plied to th e soil or crop. If th e

formulation is an insecticide, the vapors of the active ingredient often do

mos t of th e killing of the pes t. If it is a h erbicide, th e liqu id ha s to b e

incorporat ed into th e soil before it tur ns to a gas ; otherwise it will be lost to

the atm osph ere. Phosp hine, one of the m ost common fum igants for stored

grain, is inserted as a solid capsule into the grain, where it vaporizes.

Fum igants pose a seriou s s afety risk becau se th ey are highly toxic an d

easily inhaled. They can also burn the skin.

Poisonous baits are foods or other su bsta nces m ixed with a pesticide tha t

will attract a nd be eaten by pests a nd cau se their death. They are u sed to

control mice, rats, an d other rodents an d an ima ls. Baits are also used to

control ants, flies, or other insects, including some soil pests. Bait



Pest ic i de Formulat i ons Page 4 -61

formu lations can be u sed in whole areas or for spot treatmen t, ind oors and

out. The percentage of active ingredient is low compared to ECs and other

formulations.

Aerosols are sold ma inly for garden an d h ome u se, not for agricultura l use.

They contain one or more pesticides in th e sam e formu lation in a can

under pressure. Usually the percentage of active ingredients is very low.

Their main advantage is that they are convenient to use.

Invert emulsions contain a water-soluble pesticide dispersed in an oil

carrier. They require a special kind of emulsifier that allows the pesticide

to be mixed with a large volu me of oil, us u ally a fuel oil. When ap plied,

invert emulsions form large droplets which do not drift easily. Invert

emulsions are most often used along rights-of-way where there is a

problem of pest icide drift on n on-ta rget plants .

Adjuvants

An adjuvan t is an inert ma terial add ed to a pesticide formu lation. It h elps

increase the effectiveness of the active ingredient. Most pesticide

formulations contain at least a small percentage of additives.Some applicators also add adjuvants when mixing for special applications.

Check the label first because some labels have cautions against adding

adjuvants.

Common adjuvants include wetting agents, spreaders, stickers, foaming

agents, a nd compatibility agents.

Combining Different

Formulations

Sometimes various pesticides are combined. Some pesticides are

registered for use in combination with a liquid fertilizer. If pesticides may

be combined safely and effectively, they are called compatible. If not, th ey

are called incompatible. Incompatibility can be physical or chemical.

Phys ical incompa tibility means that the chemicals cannot physically be

mixed together. Solid materials may become deposited at the bottom of the

spra y tank or th e ingredients m ay become sepa rated into two or more

layers following agitation. In some cases, separate parts may come

together or foaming or curdling may occur. If chemicals are physically

incompatible, the mixture may not be sprayable or the concentrations may

vary.

Chem ical incompatibility . Even if some chemicals can be mixed together

physically, there may be other kinds of incompatibility that may reduce

effectiveness or cause injury to the plant.

Pesticide manufacturers try to anticipate combinations that farmers want

to u se a nd provide warn ings on the label for incomp atible mixtures.



Page 4 -62 Pr i vate Pest i c i de App l i cator T ra in ing Manua l

Summary

Pesticides come in various formulations. Some are easier to use than

others. Some are more effective than others in certain situations. The

most commonly used formulations are emulsifiable concentrates and

wettable powders, bu t th ere are m an y other types available. It is imp ortant

to know which type of formulation is the safest and most effective for the

crop and pest you wish to treat. Do not comb ine pesticides th at ar e

ph ysically or ch emically incomp atible.

18 3 4 formulations

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