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CHAPTER 4
PESTICIDE FORMULATION
AND DILUTION
I. PESTICIDE FORMULATIONS
The components of pesticide products which have pesticidial activity are
called active ingredients. A particular product may contain more than one ac-
tive ingredient. Active ingredients are rarely used applied in their pure form. In-
stead, they are normally mixed with inert (inactive) ingredients so that you can
handle them more conveniently and safely and apply them more easily and
efficiently. This mixture of active and inert ingredients is called a pesticide
formulation. The final pesticide formulation is ready for use, either as pack-
aged or after dilution with solvents (e.g., water or petroleum) or other carriers
(e.g., silica or silicates).
Pesticides, then, are formulated into many usable forms for satisfactory
storage, for effective application, for safety to the applicator and the environ-
ment, for ease of application with readily available equipment, and for econ-
omy. These goals are not alway s early accom plished, due to the chemi cal
and physical characteristics of the technical grade pesticide. For example,
some materials in their "raw" or technical condition are liquids, others solids;
some are stable to air and sunlight, whereas others are not; some are volatile,
others are not; some are water soluble, some oil soluble, and others may be
insoluble in either water or oil. These characteristics pose problems to the
formulator since the final formulated product must meet the standards of ac-
ceptability by the user.
There are many kinds of pesticide formulations available in the market-
place. There are two main reasons for this. First, the chemistry of the active
ingredient itself dictates what formulations are possible. For example, some
active ingredients are water-soluble and others are not; the latter, then, are of-
ten formulated in organic solvents (e.g., petroleum, hexane, or xylene) instead
of water. Second, different formulations offer different advantages; thus, one
formulation may be better than another for a given application. For example,
some active ingredients that are commonly formulated as granules may also be
available as liquids so that they can be applied through irrigation systems.
© 1998 by CRC Press LLC
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Pesticides are more extensively applied as liquids than as solids. Even
some dry formulations, such as wettable powders, are diluted or suspended in a
liquid before being applied. Different formulations present different hazards to
the applicator. Figure 4.2 describes the hazards of various formulations.
Figure 4.1 Illustration of the different pesticide formulations and packages
available (EPA, Protect Yourself from Pesticides, 1993).
A. TYPES OF FORMULATIONS
1. Emulsifiable Concentrates
Emulsifiable concentrates (EC or E are commonly used abbreviations fol-
lowing the trade name on the package) are the most commonly used formula-
tions. The active ingredients in these formulations are insoluble in water.
Thus, they are dissolved in an organic or petroleum-based solvent (which
gives ECs their strong odor); emulsifiers are then added to the solution. The
emulsifiers have properties similar to household detergents and soaps and al-
low the pesticide to be effectively mixed with water. In water, ECs form
"milky" suspensions, called emulsions. Only slight agitation is required to
maintain the suspension.
On the product label, the active ingredient in emulsifiable concentrates is
given as a percentage or as pounds per gallon; concentrations normally range
© 1998 by CRC Press LLC
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from 2 to 8 pounds per gallon. Because of the relatively high percentage of
active ingredient, you usually do not need to handle a large amount of product
for a particular job. At the same time, it is relatively easy to apply too little
or too much of the chemical.
Figure 4.2 The hazards of various formulations (EPA, Protective Clothing
for Pesticide Users, poster).
Because of their high concentrations and liquid form, emulsifiable concen-
trates may be hazardous to the applicator because the skin readily absorbs the
solvent carrier. Care must be taken when handling this type of formulation.
Figure 4.3 shows a bulk container of an emulsifiable concentrate with a DOT
label.
Emulsifiable concentrates leave little visible residue on plants. However,
some plants are sensitive to the solvents and additives and damage (sometimes
termed phytotoxicity) may occur. For this reason, an emulsifiable concentrate
formulation may not be registered for a particular plant, even though wettable
powder and dust formulations of the same active ingredient can be used.
Because little agitation of the spray suspension is needed, emulsifiable
concentrates are especially suitable for low-pressure, low-volume sprayers and
for mist blowers. You can also use them with many other types of applica-
tion equipment, including dilute hydraulic sprayers, low-volume ground spray-
ers, mist blowers, and low-volume aerial sprayers.
© 1998 by CRC Press LLC
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Figure 4.3 Bulk container showing labels indicating an emulsifiable concen-
trate with a flammable carrier solution.
Emulsifiable concentrates are not abrasive and won't separate when the
sprayer isn't running. The solvents in emulsifiable concentrates may cause
rubber hoses, gaskets, and pump parts to deteriorate rapidly unless they are
made of neoprene rubber or more resistant materials.
2. Wettable Powders
Wettable powders (WP or W) are finely divided, relatively insoluble pow-
ders. The active ingredients are combined with a dry diluent (inert carrier) such
as clay, talc, or silica and with wetting agents (surfactants) and/or dispersing
agents. Without the wetting agent, the powder would float when added to wa-
ter, and the two would be almost impossible to mix. The formulated product
normally contains 15% to 95% active ingredient; usually 25% or more. Wet-
table powders form a suspension rather than a true solution when added to wa-
ter or liquid fertilizer. Therefore, constant and vigorous agitation is needed in
the spray tank to maintain the suspension because the wettable powder sepa-
rates quickly when the sprayer is turned off.
© 1998 by CRC Press LLC
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Wettable powders are easy to store, transport, and handle, but are hazard-
ous to the applicator, particularly in mixing where the concentrated dust may
be inhaled; however, they are usually not, absorbed through the skin as readily
as emulsifiable concentrates.
Many of the insecticides sold for garden use are in the form of wettable
powders because there is very little chance that this formulation will burn fo-
liage, even at high concentrations. In contrast, the original carrier in emulsifi-
able concentrates is usually an aromatic solvent, which in relatively moderate
concentrations can cause foliage burning at temperatures above 32.5ºC (90ºF).
Wettable powders can be used with most types of application equipment.
As long as the suspension is adequately maintained, they will not clog noz-
zles, provided strainers and nozzle screens are sufficiently large. WPs are abra-
sive, however, and may cause both pumps and nozzles to wear more quickly.
3. Water-Soluble Powders or Soluble Powders
In water-soluble powders or soluble powders (WSP or SP), the technical
grade material is a finely ground, water-soluble solid and may contain a small
amount of wetting agent to assist its solution in water. It is simply added to
the spray tank, where it dissolves immediately. Unlike the wettable powders
and flowables, these formulations do not require constant agitation. They
form true solutions and form no precipitate. Because of their sometimes dusty
quality, soluble powders may be packaged in convenient, water-soluble bags
which are simply dropped into the spray tank. Examples of these are the ni-
cosulfuron herbicide Accent® SP and the linuron herbicide Lorox® SP.
4. Water-Soluble Bags
Some wettable and soluble powders are sold in water-soluble bags or
packs (WSB or WSP). These products are formulated in a soluble package so
that the inner bag is placed directly in the spray tank and subsequently dis-
solves. This type of packaging eliminates the need for measuring and mini-
mizes your risk of exposure. Examples of this packaging are PounceÚö WSB,
AmmoÚö WSB, and BrigadeÚö WSB, all of which are products of the FMC
Corporation.
5. Water-Soluble Concentrates, Liquids or Solutions
The active ingredient in water-soluble liquids or concentrates (S, WS,
WSC or WSL) is soluble in water and is formulated either with water or with
a solvent, such as alcohol, which mixes readily with water. When added to
water in the spray tank, WSCs form a true solution and require no further agi-
© 1998 by CRC Press LLC
6
tation after they are mixed. Water-soluble concentrates are often liquid, salt,
or amine solutions (e.g., TouchdownÚö 38-SL a water-soluble liquid).
6. Oil Solutions
The active ingredient in oil solutions is formulated either with oil or with
some other organic solvent. The formulation may be highly concentrated so
that further dilution with oil is required before application or it may be sold in
a dilute form ready for application. In either case, they are true solutions and
agitation is not necessary to maintain them.
In their commonest form, oil solutions are the ready-to-use household and
garden insecticide sprays sold in a variety of bottles, cans, and plastic contain-
ers, all usually equipped with a handy spray atomizer. Not to be confused
with aerosols, these sprays are intended to be used directly on pests or places
they frequent.
Oil solutions may be used as roadside weed sprays, for marshes and stand-
ing pools to control mosquito larvae, in fogging machines for mosquito and
fly abatement programs, or for household insect sprays purchased in super-
markets. Commercially they may be sold as oil concentrates of the pesticide
to be diluted with kerosene or diesel fuel before application or in the dilute,
ready-to-use form. In either case, the compound is dissolved in oil and is ap-
plied as an oil spray; it contains no emulsifier or wetting agent.
As with the emulsifiable concentrates, oil solution may cause damage to
vegetation because of the high concentration of solvent; they also may cause
significant deterioration of rubber sprayer components. The high-concentrate
solutions must be handled with particular caution.
Examples of oil solutions are the dormant oils which are used to control
scale insects in trees (see Figure 4.4).
7. Flowables or Sprayable Suspensions
Flowables (F, FL), sometimes called water-dispersible suspensions, are
particularly useful formulations for active ingredients that are not soluble in
either water or the more commonly available organic solvents. The active
ingredient is impregnated on a diluent such as clay, which is then milled to an
extremely fine powder. The powder is then suspended in a small amount of
liquid so that the resulting formulation is thick, like paste or cream. Flow-
ables are essentially WPs in suspension that you can measure by volume.
They combine the benefits of both WPs and ECs and are becoming increas-
ingly popular. They are mixed with water or liquid fertilizer to form suspen-
sions which require moderate agitation in the spray tank. Because they are
© 1998 by CRC Press LLC
7
more finely divided than WPs, flowables generally require less agitation and
can be applied in less total liquid per acre. They seldom clog spray nozzles
and usually handle as well as ECs, although they do require larger strainers and
nozzle screens than ECs. There are fewer phytotoxicity problems with flow-
ables than with Ecs.
Figure 4.4 Dormant Oil Spray® is used to control scale and mite eggs on
fruit, shade trees, roses and shrubs. It contains paraffinic oil as the active
ingredient.
8. Dry Flowables
Dry Flowables (DF) are finely divided powders that are formulated into
concentrated, dustless granules. Dry flowables form a suspension in water and
require some agitation to maintain a uniform spray mixture. The principal
advantage of this formulation is that although it is sold in the dry form, it is
not a dust and can be handled easily. Dry flowables are not meant to be applied
© 1998 by CRC Press LLC
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directly through a granular applicator; unlike granules designed for application
in the dry form, these formulations contain a high percentage of active ingre-
dients, often as much as 75% to 90%.
9. Ultralow-Volume Concentrates
An ultralow-volume concentrate (ULV) application is defined as a spray
application of undiluted formulation at a rate less than or equal to 1/2 of a
gallon per acre. The formulation may contain only the active ingredient or the
active ingredient in a small amount of solvent. Always apply ULV formula-
tions without further dilution. These formulations often require specialized
application equipment and are usually, though not always, applied by air.
The principal advantage of a ULV application is that many acres can be
sprayed with a small volume of liquid. There is some concern that there may
be a greater likelihood of significant drift with ULV sprays than with dilute
solutions, but the evidence is not conclusive. ULV applications are now lim-
ited principally to a small number of insecticides on a few sites.
ULV application is prohibited unless it is specifically designated on the
label or is based on an official written or published recommendation of the
EPA and the state agency with the regulatory authority for pesticides.
10. Encapsulated or Microencapsulated Formulations
The active ingredient (liquid or dry) is incorporated by a special process in
small, permeable spheres of a polymer or plastic, 15 to 50 µm (1 µm = 10-6 m)
in diameter. These spheres are then mixed with wetting agents, thickeners,
and water to give the desired concentration of pesticide in a flowable form,
usually 2 pounds per gallon. After the required dilution, the pesticide spray
mixture can be applied with conventional sprayers. The pesticide is released
gradually over a period of time.
Encapsulated materials can be handled with relative case and safety. They
are effective longer than other formulations containing the same active ingre-
dient. Insecticides formulated this way may, however, pose a significant haz-
ard for bees because bees may take capsules with pollen back to the hive.
11. Dusts
Dusts (D) have been the simplest formulations of pesticides to manufac-
ture and the easiest to apply. Dusts are formulated for application in the dry
form and with few exceptions, they should be used as purchased.
© 1998 by CRC Press LLC
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A prepared dust is a finely ground, dry mixture consisting of a low con-
centration of active ingredient (usually 1% to 10% by weight) combined with
an inert carrier. Because dust particles are finely ground, they may drift long
distances from the treated area even when wind velocities are low. Herbicides
are not formulated as dusts principally because of this potential for drift.
Dusts present a significant inhalation hazard to the applicator and leave a visi-
ble residue on plants. They are of limited importance in ornamental and turf
pest control.
Despite their ease in handling, formulation, and application, dusts are the
least effective and, ultimately, the least economical of the pesticide formula-
tions. The reason is that dusts have a very poor rate of deposit on foliage,
unless it is wet from dew or rain. In agriculture, for instance, an aerial appli-
cation of a standard dust formulation of pesticide will result in 10 percent to
40 percent of the material reaching the crop. The remainder drifts upward and
downwind.
12. Granules
Granules are very much like dusts except that the inert particles are much
larger. Granules are normally made by applying a liquid formulation of the
active ingredient (ranging from 2% to 40% by weight) to particles of clay or
other porous materials such as corn cobs or walnut shells.
Following application, the active ingredient is released gradually from the
inert material. Granules are generally less susceptible to degradation and
leaching than other soil-applied formulations. Because granules are relatively
large, they drift less than most other formulations and there is little inhalation
hazard. However, it is often difficult to accurately calibrate granular spreaders
and to obtain uniform distribution of the granules.
Granular formulations are used almost exclusively as soil treatments.
They may be applied either directly to the soil or over the plants; they do not
cling to plant foliage. They may be used to control pests living at or below
ground level or they may be absorbed by roots and translocated throughout the
plant. The latter are, for the most part, either systemic insecticides or sys-
temic herbicides.
Only insecticides and a few herbicides are formulated as granules. They
range from 2 to 25 percent active ingredient and are used almost exclusively in
agriculture, although systemic insecticides as granules can be purchased for
lawn and ornamentals. Granular materials may be applied at virtually any
time of day, since they can be applied aerially in winds up to 20 mph without
problems of drift, an impossible task with sprays or dusts. They also lend
themselves to soil application in the drill at planting time to protect roots
© 1998 by CRC Press LLC
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from insects or to introduce a systemic to roots for transport to above-ground
parts in lawns and ornamentals.
13. Poisonous Baits
A poisonous bait is a pesticide mixed with an edible material that is at-
tractive to a particular pest. The pests are killed by consuming a lethal dosage
of the poison either in a single feeding or over a period of time. Baits are
sometimes used to control rodents. Although you may not need to cover the
whole area, the bait must be placed where it is likely to be consumed.
The percentage of active ingredient in bait formulations is quite low, usu-
ally less than 5%; in addit ion, only small amoun ts of pesti cide are used in
relat ion to the effective area of treatment. Because the "method of application"
also limit s the amoun t of pesti cide intro duced into the envir onment, envi-
ronmental contamination can be minimized. Baits may, however, be attractive
to non-target organisms. If a bait is not adequately selective, extra caution
shoul d be used to preve nt non-t arget organisms from reaching it, either by
placi ng it properly or by using scree ns, boxes, or other types of physi cal
barri ers.
14. Fumigants
Fumigants are a rather loosely defined group of formulations. They are a
substance or mixture of substances which produce gas, vapor, fume, or smoke
intended to destroy insects, bacteria, or rodents. Fumigants may be volatile
liquids and solids as well as gases. They are used to disinfest the interiors of
buildings, objects and materials that can be enclosed so as to retain the fumi-
gant. Soil fumigants are also used in horticultural nurseries, greenhouses, and
on high-value cropland, such as tobacco, to control nematodes, insect larvae
and adults, and sometimes to control diseases and weed seeds. Depending on
the fumigant, the treated soils may require covering with plastic sheets for
several days to retain the volatile chemical, allowing it to exert its maximum
effect.
15. Adjuvants (Additives)
An adjuvant or additive is a chemical added to a pesticide to increase its ef-
fectiveness or to reduce its phytotoxicity or drift. Adjuvants are used most
extensively in products designed for foliar applications. Most pesticide formu-
lations already contain adjuvants. Several different types of adjuvants are:
Wetting agents and emulsifiers are often added so that the pesticide will
mix with water and/or coat treated surfaces more effectively.
© 1998 by CRC Press LLC
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Spreaders are substances that increases the area that a given volume of liquid
will cover on a solid or another liquid. They also allow pesticides to spread
evenly over treated surfaces.
Stickers increase the adherence of the chemical to the treated surface, thus
increasing its persistence, particularly under adverse weather conditions. Many
spreaders also possess wetting and spreading characteristics.
Penetrants are wetting agents, oils, or oil concentrates that enhance the absorp-
tion of a systemic pesticide by the plant. Examples are Agri-DexÚö, InduceÚö,
and PenetratorÚö.
Dispe rsing agent s are materials that reduc e the cohesiveness of like parti-
cles, either solid or liquid. Dispe rssants and suspe nding agent s are added
during the formulation of emulsifiable concentrates and wettable powders to aid
in the dispersion and suspension of the ingredients. Examples are AdherexÚö,
TamolÚö, and LomarÚö.
Foaming aids and suppressants are surface-active substances that forms a
fast draining foam to provide maximum contact of the spray to the plant sur-
face. Foaming aids insulate the surface and reduce the rate of evaporation.
Foaming suppressants reduce the ability of a pesticide or formulation to foam
during mixing and application.
Formulations as manufactured often contain all necessary adjuvants in ap-
propriate amounts for all or most uses. Sometimes, however, it may be de-
sirable for the applicator to add specific adjuvants prior to application. Wet-
ting agents and spreader-stickers are probably the adjuvants added most fre-
quently by the applicator. These materials are often referred to as surfactants.
Surfactants are "surface active agents" which reduce the surface tension of wa-
ter and therefore enhance spreading of the spray solution on the treated surface.
Compatibility agents are being added with increasing frequency to allow the
effective mixing of two or more pesticides or a pesticide with a fertilizer.
Thickening agents, also called drift reduction agents, are being used more ex-
tensively as drift continues to be of increasing concern.
Adjuvants are added only if recommended on the product label; otherwise,
you will do so at your own risk. Some labels expressly prohibit the use of
adjuvants. Always bear in mind that while increasing the effectiveness of a
particular pesticide, you also may be increasing the potential for phytotoxicity
and perhaps harm to non-target organisms and the environment.
© 1998 by CRC Press LLC
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II. DILUTING PESTICIDES CORRECTLY
Unless you have the correct amount of pesticide in your tank mix, even a
correctly calibrated sprayer can apply the wrong dose of pesticide to the target.
Formulations such as wettable and soluble powders, emulsifiable concen-
trates, and flowables are sold as concentrates and must be diluted in the spray
tank with an appropriate carrier. Water is the most common carrier, but kero-
sene, oil, and other liquids are sometimes used. The label or other recommen-
dations will tell:
" how much to dilute the formulation
" how much of the dilute pesticide to apply per unit of area.
A. MIXING SOLUBLE AND WETTABLE POWDERS
1. Pounds Per 100 Gallons
Directions for wettable or soluble powders may be given in pounds of
pesticide formulation per 100 gallons of carrier. You must know the capacity
in gallons of your sprayer tank (or the number of gallons you will be adding
to your spray tank if the job requires only a partial tank load). Then use the
following formula:
Gallons in tank × lbs. per 100 gal. Recommended = Pounds needed in tank
100 gallons
Example 1:
Your spray tank holds 500 gallons. The label calls for 2 pounds of for-
mulation per 100 gallons of water. How many pounds of formulation should
be added to the tank?
500 gallons x lbs. per 100 gallons (2 )
= Pounds needed in tank (10)
100 gallons
500 x 2 ÷ 100 = 10 You should add 10 pounds to the tank.
© 1998 by CRC Press LLC
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Example 2:
You need to spray only one acre and your equipment is calibrated to spray
60 gallons per acre. The label calls for 2 pounds of formulation per 100 gal-
lons of water. How many pounds of formulation should be added to the tank
to make 60 gallons of finished spray?
Gallons in tank (60) x Ibs. per 100 gallons (2)
= 1.2 lbs. (19 oz.) in tank
100 gallons
2. Pounds Per Acre
The label may list the recommended dosage as pounds per acre. If the job
requires a full tank, you must know how many gallons your equipment ap-
plies per acre and the spray tank capacity. Use these formulas:
Gallons in tank = Acres sprayed per tankful
Gallons applied per acre
Acres sprayed per tank x Pounds formulation per acre = Pounds formulation needed
in tank
Example: 3
Your sprayer applies 15 gallons per acre and your tank holds 400 gallons.
The label rate is 3 pounds of formulation per acre.
Gallons in tank (400) = 26.7 acres sprayed per tankful
Gallons per acre (15)
400 ÷ 15 = 26.7
Acres sprayed per tankful (26.7) x Pounds formulation per acre (3) = Pounds
needed in tank (80.1)
26.7 × 3 = 80.1
Add 80 pounds of pesticide formulation to the tank.
© 1998 by CRC Press LLC
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If the job requires less than a full tank, you must know how many acres
you wish to treat and how many gallons your sprayer is pumping per acre.
Figure both the number of gallons needed in the tank and the pounds of for-
mulation to add. Use these formulas:
Gallons per acre x Acres to be treated = Gallons needed in tank
Acres to be treated x Pounds formulation per acre = Pounds formulation needed
in tank
Example: 4
You wish to spray 3.5 acres and your equipment is applying 15 gallons
per acre. The label rate is 3 pounds per acre.
Gallons per acre (15) x Acres to be treated (3.5) = Gallons needed in tank (52.5)
15 x 3.5 = 52.5
Acres to be treated (3.5) X Pounds formulation per acre (3) = Pounds formula-
tion (10.5) needed in tank
3.5 x 3 = 10.5
If the recommended dosage is given as pounds of active ingredient per
acre, you must first convert that figure to pounds of formulation per acre. Use
the following formula:
Pounds of active ingredient per acre x 100
= Pounds formulation per acre
Percent of active ingredient in formulation
Then follow the formulas listed above under "pounds per acre" to find the
pounds of formulation to add to your tank.
Example 5:
You wish to apply 2 pounds of active ingredient per acre. Your formula-
tion is 80 percent WP.
Pounds of a.i. per acre (2) x 100 = 2.5 pounds formulation per acre
% a.i. in formulation (80)
2 x 100 ÷ 80 = 2.5
© 1998 by CRC Press LLC
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If the recommended rate is a percentage of active ingredient in the tank,
another formula is necessary. First find the number of gallons of spray in the
spray tank (either the tank capacity or gallons needed for job if less than tank
capacity). Then:
Gallons of spray in tank x % a.i. wanted x Weight of carrier (lbs. per gal.)
% active ingredient in formulation
= Pounds formulation to add to tank
Example 6:
Your mist blower directions call for a spray containing 1.25 percent active
ingredient. You need to mix 40 gallons of spray for the job. The pesticide is
a 60 percent SP and you will use water as the carrier.
Gallons of spray (40) x % a. i. needed (1.25) X Weight of water/gal (8.3)
% active ingredient in formulation (60)
= 6.9 pounds formulation needed in tank (40 x 1.25 x 8.3 . 60 = 6.9 Ibs.)
B. MIXING LIQUID FORMULATIONS
Dosages for liquid formulations (EC, F, SC, etc.) are often listed as pints,
quarts, or gallons per 100 gallons or per acre. Use the pounds per 100 gallons
and pounds per acre (above) for making these calculations. Substitute the ap-
propriate liquid measure for "pounds" in the formulas.
Example 7:
The label rate is 2 pints of pesticide formulation per 100 gallons of water.
Your spray tank holds 300 gallons.
Gallons per tank (300) x pints per 100 gal. (2) = 300 X 2 ÷ 100 = 6
100 gallons
6 pints formulation needed in tank
© 1998 by CRC Press LLC
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Example 8:
Your sprayer applies 22 gallons per acre and your tank holds 400 gallons.
The label rate is 1.5 quarts per acre.
Gallons in tank (400) X quarts per acre (1.5) = 400 X 1.5 ÷ 22 =
Gallons per acre (22)
27.3 qts. needed in tank
If the recommendation for the liquid formulation is listed as pounds of ac-
tive ingredient per acre, you must first convert that figure to gallons of formu-
lation to apply per acre. The label of a liquid formulation always tells how
many pounds of active ingredient are in one gallon of the concentrated formu-
lation (4 EC has 4 pounds of active ingredient per gallon; 6 EC contains 6
pounds per gallon, etc.).
Pounds of active ingredient needed per acre
Pounds of active ingredient per gallon of formulation
= Gallons of formulation per acre
Example 9:
The recommendation is for 1 pound of active ingredient per acre. You
purchased an 8 EC, which contains 8 pounds of active ingredient per gallon.
Your tank holds 500 gallons and is calibrated to apply 25 gallons per acre.
Pounds a.i. to apply per acre ( 1 ) = 1 ÷
÷ 8 = .125 (1/8)
÷
÷
Pounds a.i. per gallon (8)
1/8 gallons (1 pint) per acre
Gallons in tank (500) = 500 ÷ 25 = 20 Acres per tankful
Gallons per acre (25)
Acres per tankful (20) X gallons per acre (1/8 or .125) = Gallons to add to
tank (2.5)
20 x .125 = 2.5
© 1998 by CRC Press LLC
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If the recommended rate is a percentage of active ingredient in the tank,
use this formula:
Gallons of spray x % a.i. wanted x Weight of carrier ( lbs/gal)_
lbs. a.i. per gallon of formulation
= Gallons of formulation to add
Example 10:
You wish to make 100 gallons of a 1 percent spray using water as the car-
rier. You have a 2 EC formulation (2 pounds active ingredient per gallon).
How many gallons of the 2 EC should you add to the 100 gallons of water in
the tank?
Gallons of spray (100) x % a.i. wanted ( 1 ÷ 100) x Weight of water (8.3)
lbs. a.i. per gallon of formulation (2)
= 100 X .01 x 8.3 ÷ 2 = 4.15 gals of formulation to add
C. MIXING CONCENTRATES FOR AIR BLAST SPRAYERS
OR MIST BLOWERS
If the dosage recommendations are listed as pounds or gallons per acre or
pounds or gallons per 100 gallons of carrier for use in boom or hydraulic
sprayers, you will need to convert the dosage to the concentration factor you
have chosen (usually 2X, 3X, 4X, 5X, or 10X). Simply follow the steps
listed above for the dry or liquid formulation you are using. The last answer
should be multiplied by the concentration factor.
Pounds or gallons of formulation per tank x Concentration factor = Pounds
or gallons formulation per tank in concentrate form
© 1998 by CRC Press LLC
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Example 11:
The label lists the dosage as 4 pounds formulation per 100 gallons of wa-
ter for dilute application. Your air blast sprayer tank holds 600 gallons. You
wish to apply a 5X concentration.
Gallons per tank (600) x lbs. per 100 gallons recommended (4)
100 gallons
= lbs. needed in tank for hydraulic sprayer (24)
600 x 4 ÷ 100 = 24
Pounds formulation per tank for hydraulic sprayer (24) x Concentration wanted
(5X) = Pounds of formulation to add to air blast tank (120)
24 x 5 = 120
REFERENCES
Baker, P. B., Arizona Agricultural Pesticide Applicator Training Manual,
Co-operative Extension, University of Arizona, Tucson, AZ, 1992.
Bohmont, B. L., The Standard Pesticide User's Guide, 4th. ed., Prentice Hall,
NJ, 1997. Litigation Manual, Clark Boardman Callaghan, New York,
NY, 1996.
U.S. Environmental Protection Agency, Applying Pesticides Correctly: A
Guide for Private and Commercial Applicators, revised 1991.
U.S. Environmental Protection Agency, Applying Pesticides Correctly: A
Guide for Private and Commercial Applicators, 1983.
U.S. Environmental Protection Agency, The Worker Protection Standard for
Agricultural Pesticides How to Comply: What Employers Need to
Know, 1993.
U.S. Environmental Protection Agency, Protective Clothing for Pesticide
Users Poster, 1993.
© 1998 by CRC Press LLC
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