Page 8-Corn Talk, Lancaster Farming, Saturday, April 17,1993
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PENNSYLVANIA MASTER CORN GROWERS ASSOC., INC.
Adjuvants Enhance
of the spray solution including
surface tension, density, vola
tility, and solubility. These
properties will in turn modify
the spreading, wetting, reten
tion, and penetration of the
spray solution. It is important
that the appropriate adjuvant is
selected for a particular pesti
cide product. The type of adjuv
ant added to the spray tank can
enhance or reduce the perfor
mance of the pesticide. The
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herbicides. Not only does cuti
cle composition vary between
species, but also the age of the
plant has been associated to dif
ferences in leaf wax chemistry
over time.
The most common types of
activator adjuvants employed
are surfactants, oils, and salts.
Activator adjuvants influence
the physicochemical properties
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relative effectiveness of several
adjuvants on herbicide perfor
mance is shown in Table 2. In
both these trials, nonionic sur
factant was less effective than
other types of adjuvants; how
ever, with other weeds or herbi
cides nonionic surfactant might
be the more appropriate choice.
The first step in choosing the
correct additive for a specific
product is to read the pesticide
label. The wrong adjuvant may
increase the risk of poor perfor
mance and/or crop injury.
Surfactants
The primary purpose of a
surfactant or “surface active
agent” is to reduce the surface
tension of the spray solution in
order to allow more intimate
• Increase Root Mass
• Increase Tillering
• Optimize Nutrient Efficiency
• Increase Drought Tolerance
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contact between the spray dro
plet and the plant surface. Any
substance that brings a pesti
cide into closer contact with the
leaf surface has the potential to
aid absorption.
Surface tension is a measure
of the surface energy in terms
of force measured in dynes/cm.
Water has a surface tension of
73 dynes/cm. Surfactants lower
the surface tension of water to
that of an oil or solvent which
spread more readily than water
on plant surfaces. Surfactants
typically lower the surface ten
sion of a solution to between 30
and SO dynes/cm.
The interaction between sur
factant, herbicide, and plant
surface is far more complex
than simply lowering the sur-
Details or Call:
INC.
face tension of the pesticide
solution. Surfactant molecules
may also alter the permeability
of the cuticle. Surfactants form
a bridge between unlike chemi
cals such as oil and water or
water and the wax on a leaf
surface.
There are many different
types of surfactants. In general,
they are constructed of a long
chain hydrocarbon group on
one end which is considered
lipophilic (fat loving) and a
more hydrophilic (water lov
ing) group of atoms on the other
end. The structure of surfac
tants is often represented by a
tadpole or polliwog type of
arrangement such as seen in
Figure 1.
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